diff --git "a/pgsql-performance.200511" "b/pgsql-performance.200511" new file mode 100644--- /dev/null +++ "b/pgsql-performance.200511" @@ -0,0 +1,54148 @@ +From pgsql-performance-owner@postgresql.org Mon Oct 31 22:00:19 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5ACBCDB5CD + for ; + Mon, 31 Oct 2005 22:00:18 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 29861-05 + for ; + Tue, 1 Nov 2005 02:00:14 +0000 (GMT) +Received: from cassarossa.samfundet.no (cassarossa.samfundet.no + [129.241.93.19]) + by svr1.postgresql.org (Postfix) with ESMTP id CF951DB5CB + for ; + Mon, 31 Oct 2005 22:00:16 -0400 (AST) +Received: from trofast.sesse.net ([129.241.93.32]) + by cassarossa.samfundet.no with esmtp (Exim 4.50) + id 1EWlRh-0002iE-MA; Tue, 01 Nov 2005 03:00:18 +0100 +Received: from sesse by trofast.sesse.net with local (Exim 3.36 #1 (Debian)) + id 1EWlRq-0001G6-00; Tue, 01 Nov 2005 03:00:26 +0100 +Date: Tue, 1 Nov 2005 03:00:26 +0100 +From: "Steinar H. Gunderson" +To: PostgreSQL +Cc: pgsql-performance@postgresql.org +Subject: Re: 8.1beta3 performance +Message-ID: <20051101020026.GA4707@uio.no> +Mail-Followup-To: PostgreSQL , + pgsql-performance@postgresql.org +References: +MIME-Version: 1.0 +Content-Type: text/plain; charset=utf-8 +Content-Disposition: inline +In-Reply-To: +X-Operating-System: Linux 2.6.14-rc5 on a x86_64 +X-Message-Flag: Outlook? --> http://www.mozilla.org/products/thunderbird/ +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.009 required=5 tests=[AWL=0.009] +X-Spam-Score: 0.009 +X-Spam-Level: +X-Archive-Number: 200510/488 +X-Sequence-Number: 15256 + +On Mon, Oct 31, 2005 at 05:16:46PM -0600, PostgreSQL wrote: +> We're running 8.1beta3 on one server and are having ridiculous performance +> issues. This is a 2 cpu Opteron box and both processors are staying at 98 +> or 99% utilization processing not-that-complex queries. Prior to the +> upgrade, our I/O wait time was about 60% and cpu utilization rarely got very +> high, now I/O wait time is at or near zero. + +It sounds like some query got planned a different way that happened to be +really suboptimal -- I've seen really bad queries be quick on earlier +versions "by accident" and then not have the same luck on later versions. + +Could you find out what queries are taking so long (use +log_min_duration_statement), and post table definitions and EXPLAIN ANALYZE +output here? + +/* Steinar */ +-- +Homepage: http://www.sesse.net/ + +From pgsql-performance-owner@postgresql.org Mon Oct 31 22:06:10 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 70E99DB5D5 + for ; + Mon, 31 Oct 2005 22:06:09 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 31297-02 + for ; + Tue, 1 Nov 2005 02:06:04 +0000 (GMT) +Received: from mailbox.samurai.com (mailbox.samurai.com [205.207.28.82]) + by svr1.postgresql.org (Postfix) with ESMTP id 5E63BDB5CE + for ; + Mon, 31 Oct 2005 22:06:06 -0400 (AST) +Received: from localhost (mailbox.samurai.com [205.207.28.82]) + by mailbox.samurai.com (Postfix) with ESMTP id CDCE42399F3; + Mon, 31 Oct 2005 21:06:10 -0500 (EST) +Received: from mailbox.samurai.com ([205.207.28.82]) + by localhost (mailbox.samurai.com [205.207.28.82]) (amavisd-new, + port 10024) + with LMTP id 74935-02-10; Mon, 31 Oct 2005 21:06:09 -0500 (EST) +Received: from [192.168.1.104] (d226-86-55.home.cgocable.net [24.226.86.55]) + by mailbox.samurai.com (Postfix) with ESMTP id 469E8239993; + Mon, 31 Oct 2005 21:06:09 -0500 (EST) +Subject: Re: 8.1beta3 performance +From: Neil Conway +To: PostgreSQL +Cc: pgsql-performance@postgresql.org +In-Reply-To: +References: +Content-Type: text/plain +Date: Mon, 31 Oct 2005 21:06:15 -0500 +Message-Id: <1130810775.8561.20.camel@localhost.localdomain> +Mime-Version: 1.0 +X-Mailer: Evolution 2.4.1 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at mailbox.samurai.com +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200510/489 +X-Sequence-Number: 15257 + +On Mon, 2005-31-10 at 17:16 -0600, PostgreSQL wrote: +> We're running 8.1beta3 on one server and are having ridiculous performance +> issues. This is a 2 cpu Opteron box and both processors are staying at 98 +> or 99% utilization processing not-that-complex queries. Prior to the +> upgrade, our I/O wait time was about 60% and cpu utilization rarely got very +> high, now I/O wait time is at or near zero. + +Have you done anything to verify that this is actually a problem with +8.1, and not some other change that was made as part of the upgrade +process? For example, if ANALYZE hasn't been re-run, that could cause +the plans chosen by the optimizer to be completely different. + +-Neil + + + +From pgsql-performance-owner@postgresql.org Tue Nov 1 04:03:14 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 3B315DB5DE + for ; + Tue, 1 Nov 2005 04:03:13 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 21020-10 + for ; + Tue, 1 Nov 2005 08:03:10 +0000 (GMT) +Received: from obelix.askesis.nl (laudanum.demon.nl [82.161.125.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 581F7DB309 + for ; + Tue, 1 Nov 2005 04:03:10 -0400 (AST) +Received: obelix.askesis.nl 172.31.0.1 from 172.31.1.8 172.31.1.8 via HTTP + with MS-WebStorage 6.0.6249 +Received: from Panoramix by obelix.askesis.nl; 01 Nov 2005 09:03:10 +0100 +Subject: pgbench results interpretation? +From: Joost Kraaijeveld +To: Pgsql-Performance +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Tue, 01 Nov 2005 09:03:09 +0100 +Message-Id: <1130832189.21036.19.camel@Panoramix> +Mime-Version: 1.0 +X-Mailer: Evolution 2.0.4 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.074 required=5 tests=[AWL=0.073, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.074 +X-Spam-Level: +X-Archive-Number: 200511/1 +X-Sequence-Number: 15258 + +Hi, + +I am trying to optimize my Debian Sarge AMD64 PostgreSQL 8.0 +installation, based on the recommendations from "the Annotated +POSTGRESQL.CONF Guide for +PostgreSQL" (http://www.powerpostgresql.com/Downloads/annotated_conf_80.html). To see the result of the recommendations I use pgbench from postgresql-contrib. + +I have 3 questions about pgbench: + +1. Is there a repository somewhere that shows results, using and +documenting different kinds of hard- and software setups so that I can +compare my results with someone elses? + +2. Is there a reason for the difference in values from run-to-run of +pgbench: + +The command I used (nothing else is done on the machine, not even mouse +movement): +jkr@Panoramix:/usr/lib/postgresql/8.0/bin$ ./pgbench -c 10 -t 1000 test + +Results for 4 consecutive runs: + +tps = 272.932982 (including connections establishing) +tps = 273.262622 (excluding connections establishing) + +tps = 199.501426 (including connections establishing) +tps = 199.674937 (excluding connections establishing) + +tps = 400.462117 (including connections establishing) +tps = 401.218291 (excluding connections establishing) + +tps = 223.695331 (including connections establishing) +tps = 223.919031 (excluding connections establishing) + +3. It appears that running more transactions with the same amount of +clients leads to a drop in the transactions per second. I do not +understand why this is (a drop from more clients I do understand). Is +this because of the way pgbench works, the way PostgrSQL works or even +Linux? + +jkr@Panoramix:/usr/lib/postgresql/8.0/bin$ ./pgbench -c 10 -t 10 test +tps = 379.218809 (including connections establishing) +tps = 461.968448 (excluding connections establishing) + +jkr@Panoramix:/usr/lib/postgresql/8.0/bin$ ./pgbench -c 10 -t 100 test +tps = 533.878031 (including connections establishing) +tps = 546.571141 (excluding connections establishing) + +jkr@Panoramix:/usr/lib/postgresql/8.0/bin$ ./pgbench -c 10 -t 1000 test +tps = 204.344440 (including connections establishing) +tps = 204.533627 (excluding connections establishing) + +jkr@Panoramix:/usr/lib/postgresql/8.0/bin$ ./pgbench -c 10 -t 10000 test +tps = 121.486803 (including connections establishing) +tps = 121.493681 (excluding connections establishing) + + +TIA + +-- +Groeten, + +Joost Kraaijeveld +Askesis B.V. +Molukkenstraat 14 +6524NB Nijmegen +tel: 024-3888063 / 06-51855277 +fax: 024-3608416 +e-mail: J.Kraaijeveld@Askesis.nl +web: www.askesis.nl + + + +From pgsql-performance-owner@postgresql.org Tue Nov 1 05:17:06 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id E0B18DB63C + for ; + Tue, 1 Nov 2005 05:17:04 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 49039-03 + for ; + Tue, 1 Nov 2005 09:17:01 +0000 (GMT) +Received: from linuxworld.com.au (unknown [203.34.46.50]) + by svr1.postgresql.org (Postfix) with ESMTP id CD578DB637 + for ; + Tue, 1 Nov 2005 05:17:01 -0400 (AST) +Received: from linuxworld.com.au (IDENT:swm@localhost.localdomain [127.0.0.1]) + by linuxworld.com.au (8.13.2/8.13.2) with ESMTP id jA19GxMX006160; + Tue, 1 Nov 2005 20:16:59 +1100 +Received: from localhost (swm@localhost) + by linuxworld.com.au (8.13.2/8.13.2/Submit) with ESMTP id + jA19Gwr5006157; Tue, 1 Nov 2005 20:16:59 +1100 +X-Authentication-Warning: linuxworld.com.au: swm owned process doing -bs +Date: Tue, 1 Nov 2005 20:16:58 +1100 (EST) +From: Gavin Sherry +X-X-Sender: swm@linuxworld.com.au +To: Joost Kraaijeveld +Cc: Pgsql-Performance +Subject: Re: pgbench results interpretation? +In-Reply-To: <1130832189.21036.19.camel@Panoramix> +Message-ID: +References: <1130832189.21036.19.camel@Panoramix> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[AWL=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/2 +X-Sequence-Number: 15259 + +On Tue, 1 Nov 2005, Joost Kraaijeveld wrote: + +> Hi, +> +> I am trying to optimize my Debian Sarge AMD64 PostgreSQL 8.0 +> installation, based on the recommendations from "the Annotated +> POSTGRESQL.CONF Guide for +> PostgreSQL" (http://www.powerpostgresql.com/Downloads/annotated_conf_80.html). To see the result of the recommendations I use pgbench from postgresql-contrib. +> +> I have 3 questions about pgbench: +> +> 1. Is there a repository somewhere that shows results, using and +> documenting different kinds of hard- and software setups so that I can +> compare my results with someone elses? + +Other than the archives of this mailing list, no. + +> +> 2. Is there a reason for the difference in values from run-to-run of +> pgbench: +> +> The command I used (nothing else is done on the machine, not even mouse +> movement): +> jkr@Panoramix:/usr/lib/postgresql/8.0/bin$ ./pgbench -c 10 -t 1000 test +> +> Results for 4 consecutive runs: +> +> tps = 272.932982 (including connections establishing) +> tps = 273.262622 (excluding connections establishing) +> +> tps = 199.501426 (including connections establishing) +> tps = 199.674937 (excluding connections establishing) +> +> tps = 400.462117 (including connections establishing) +> tps = 401.218291 (excluding connections establishing) +> +> tps = 223.695331 (including connections establishing) +> tps = 223.919031 (excluding connections establishing) + +Well, firstly: pgbench is not a good benchmarking tool. It is mostly used +to generate load. Secondly, the numbers are suspicious: do you have fsync +turned off? Do you have write caching enabled? If so, you'd want to make +sure that cache is battery backed. Thirdly, the effects of caching will be +seen on subsequent runs. + +> +> 3. It appears that running more transactions with the same amount of +> clients leads to a drop in the transactions per second. I do not +> understand why this is (a drop from more clients I do understand). Is +> this because of the way pgbench works, the way PostgrSQL works or even +> Linux? +> +> jkr@Panoramix:/usr/lib/postgresql/8.0/bin$ ./pgbench -c 10 -t 10 test +> tps = 379.218809 (including connections establishing) +> tps = 461.968448 (excluding connections establishing) +> +> jkr@Panoramix:/usr/lib/postgresql/8.0/bin$ ./pgbench -c 10 -t 100 test +> tps = 533.878031 (including connections establishing) +> tps = 546.571141 (excluding connections establishing) + +Well, at this rate pgbench is only running for 2 seconds! + +> +> jkr@Panoramix:/usr/lib/postgresql/8.0/bin$ ./pgbench -c 10 -t 1000 test +> tps = 204.344440 (including connections establishing) +> tps = 204.533627 (excluding connections establishing) +> +> jkr@Panoramix:/usr/lib/postgresql/8.0/bin$ ./pgbench -c 10 -t 10000 test +> tps = 121.486803 (including connections establishing) +> tps = 121.493681 (excluding connections establishing) +> + + +This degradation seems to suggest effects caused by the disk cache filling +up (assuming write caching is enabled) and checkpointing. + +Hope this helps. + +Gavin + +From pgsql-performance-owner@postgresql.org Tue Nov 1 06:05:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 4BDCDDB637 + for ; + Tue, 1 Nov 2005 06:05:45 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 67527-01 + for ; + Tue, 1 Nov 2005 10:05:42 +0000 (GMT) +Received: from obelix.askesis.nl (laudanum.demon.nl [82.161.125.16]) + by svr1.postgresql.org (Postfix) with ESMTP id D32E5DB62B + for ; + Tue, 1 Nov 2005 06:05:42 -0400 (AST) +Received: obelix.askesis.nl 172.31.0.1 from 172.31.1.8 172.31.1.8 via HTTP + with MS-WebStorage 6.0.6249 +Received: from Panoramix by obelix.askesis.nl; 01 Nov 2005 11:05:42 +0100 +Subject: Re: pgbench results interpretation? +From: Joost Kraaijeveld +To: Gavin Sherry +Cc: Pgsql-Performance +In-Reply-To: +References: <1130832189.21036.19.camel@Panoramix> + +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Tue, 01 Nov 2005 11:05:42 +0100 +Message-Id: <1130839542.3883.19.camel@Panoramix> +Mime-Version: 1.0 +X-Mailer: Evolution 2.0.4 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.073 required=5 tests=[AWL=0.072, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.073 +X-Spam-Level: +X-Archive-Number: 200511/3 +X-Sequence-Number: 15260 + +Hi Gavin, + +Thanks for answering. + +On Tue, 2005-11-01 at 20:16 +1100, Gavin Sherry wrote: +> On Tue, 1 Nov 2005, Joost Kraaijeveld wrote: +> > 1. Is there a repository somewhere that shows results, using and +> > documenting different kinds of hard- and software setups so that I can +> > compare my results with someone elses? +> +> Other than the archives of this mailing list, no. +OK. + +> > +> > 2. Is there a reason for the difference in values from run-to-run of +> > pgbench: +> Well, firstly: pgbench is not a good benchmarking tool. +Is there a reason why that is the case? I would like to understand why? +Is it because the transaction is to small/large? Or that the queries are +to small/large? Or just experience? + +> It is mostly used +> to generate load. Secondly, the numbers are suspicious: do you have fsync +> turned off? +In the first trials I posted yes, in the second no. + +> Do you have write caching enabled? If so, you'd want to make +> sure that cache is battery backed. +I am aware of that, but for now, I am mostly interested in the effects +of the configuration parameters. I won't do this at home ;-) + + +> Thirdly, the effects of caching will be +> seen on subsequent runs. +In that case I would expect mostly rising values. I only copied and +pasted 4 trials that were available in my xterm at the time of writing +my email, but I could expand the list ad infinitum: the variance between +the runs is very large. I also expect that if there is no shortage of +memory wrt caching that the effect would be negligible, but I may be +wrong. Part of using pgbench is learning about performance, not +achieving it. + +> > 3. It appears that running more transactions with the same amount of +> > clients leads to a drop in the transactions per second. I do not +> > understand why this is (a drop from more clients I do understand). Is +> > this because of the way pgbench works, the way PostgrSQL works or even +> > Linux? +> This degradation seems to suggest effects caused by the disk cache filling +> up (assuming write caching is enabled) and checkpointing. +Which diskcache are your referring to? The onboard harddisk or RAID5 +controller caches or the OS cache? The first two I can unstand but if +you refer to the OS cache I do not understand what I am seeing. I have +enough memory giving the size of the database: during these duration (~) +tests fsync was on, and the files could be loaded into memory easily +(effective_cache_size = 32768 which is ~ 265 MB, the complete database +directory 228 MB) + +-- +Groeten, + +Joost Kraaijeveld +Askesis B.V. +Molukkenstraat 14 +6524NB Nijmegen +tel: 024-3888063 / 06-51855277 +fax: 024-3608416 +e-mail: J.Kraaijeveld@Askesis.nl +web: www.askesis.nl + + + +From pgsql-performance-owner@postgresql.org Tue Nov 1 09:33:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id E234CDB68F + for ; + Tue, 1 Nov 2005 09:33:47 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 37492-09 + for ; + Tue, 1 Nov 2005 13:33:44 +0000 (GMT) +Received: from tbmail.tradebot.com + (Tradebot-Systems-1096753.cust-rtr.swbell.net [68.90.170.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 55B39DB68C + for ; + Tue, 1 Nov 2005 09:33:45 -0400 (AST) +Received: from 192.168.200.29 ([192.168.200.29]) by tbmail.tradebot.com + ([192.168.1.50]) with Microsoft Exchange Server HTTP-DAV ; + Tue, 1 Nov 2005 13:33:49 +0000 +Received: from krb06 by TBMAIL; 01 Nov 2005 07:33:49 -0600 +Subject: Re: 8.x index insert performance +From: Kelly Burkhart +To: Tom Lane +Cc: mark@mark.mielke.cc, Merlin Moncure , + pgsql-performance@postgresql.org +In-Reply-To: <19065.1130793527@sss.pgh.pa.us> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD725@Herge.rcsinc.local> + <20051031193547.GA3311@mark.mielke.cc> <18647.1130790629@sss.pgh.pa.us> + <1130792391.7026.55.camel@krb06.tradebot.com> + <19065.1130793527@sss.pgh.pa.us> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Tue, 01 Nov 2005 07:33:49 -0600 +Message-Id: <1130852029.7026.88.camel@krb06.tradebot.com> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.1 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.021 required=5 tests=[AWL=0.020, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.021 +X-Spam-Level: +X-Archive-Number: 200511/4 +X-Sequence-Number: 15261 + +On Mon, 2005-10-31 at 16:18 -0500, Tom Lane wrote: +> Kelly Burkhart writes: +> > Ha! So I'm creating an index 98% full of nulls! Looks like this is +> > easily fixed with partial indexes. +> +> Still, though, it's not immediately clear why you'd be seeing a severe +> dropoff in insert performance after 50M rows. Even though there are +> lots of nulls, I don't see why they'd behave any worse for insert speed +> than real data. One would like to think that the insert speed would +> follow a nice O(log N) rule. +> +> Are you doing the inserts all in one transaction, or several? If +> several, could you get a gprof profile of inserting the same number of +> rows (say a million or so) both before and after the unexpected dropoff +> occurs? + +I'm doing the inserts via libpq copy. Commits are in batches of approx +15000 rows. I did a run last night after modifying the indexes and saw +the same pattern. I'm dumping the database now and will modify my test +program to copy data from the dump rather than purely generated data. +Hopefully, this will allow me to reproduce the problem in a way that +takes less time to set up and run. + +Tom, I'd be happy to profile the backend at several points in the run if +you think that would be helpful. What compiler flags should I use? +Current settings in Makefile.global are: + +CFLAGS = -O2 -Wall -Wmissing-prototypes -Wpointer-arith -Winline +-Wendif-labels -fno-strict-aliasing + +Should I change this to: + +CFLAGS = -g -pg -Wall ... + +Or should I leave the -O2 in? + +It may be weekend by the time I get this done. + +-K + +From pgsql-performance-owner@postgresql.org Tue Nov 1 09:45:28 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 045FDD8127 + for ; + Tue, 1 Nov 2005 09:45:28 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 37976-08 + for ; + Tue, 1 Nov 2005 13:45:24 +0000 (GMT) +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 3BC44DB69E + for ; + Tue, 1 Nov 2005 09:45:26 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA1DjUqf024846; + Tue, 1 Nov 2005 08:45:30 -0500 (EST) +To: Kelly Burkhart +Cc: mark@mark.mielke.cc, Merlin Moncure , + pgsql-performance@postgresql.org +Subject: Re: 8.x index insert performance +In-reply-to: <1130852029.7026.88.camel@krb06.tradebot.com> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD725@Herge.rcsinc.local> + <20051031193547.GA3311@mark.mielke.cc> + <18647.1130790629@sss.pgh.pa.us> + <1130792391.7026.55.camel@krb06.tradebot.com> + <19065.1130793527@sss.pgh.pa.us> + <1130852029.7026.88.camel@krb06.tradebot.com> +Comments: In-reply-to Kelly Burkhart + message dated "Tue, 01 Nov 2005 07:33:49 -0600" +Date: Tue, 01 Nov 2005 08:45:30 -0500 +Message-ID: <24845.1130852730@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/5 +X-Sequence-Number: 15262 + +Kelly Burkhart writes: +> Tom, I'd be happy to profile the backend at several points in the run if +> you think that would be helpful. What compiler flags should I use? + +Add -g -pg and leave the rest alone. Also, if you're on Linux note that +you need -DLINUX_PROFILE. + +> It may be weekend by the time I get this done. + +Well, it's probably too late to think of tweaking 8.1 anyway... + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Tue Nov 1 10:14:43 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 00C83DB671 + for ; + Tue, 1 Nov 2005 10:14:42 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 53522-10 + for ; + Tue, 1 Nov 2005 14:14:36 +0000 (GMT) +Received: from rhws.3times25.net (duck.3times25.net [66.23.211.34]) + by svr1.postgresql.org (Postfix) with ESMTP id 05C0DDB69F + for ; + Tue, 1 Nov 2005 10:14:38 -0400 (AST) +Received: from [127.0.0.1] (localhost [127.0.0.1]) + by rhws.3times25.net (Postfix) with ESMTP + id 08F8CDB92C; Tue, 1 Nov 2005 09:14:51 -0500 (EST) +Message-ID: <4367785A.9090709@3times25.net> +Date: Tue, 01 Nov 2005 09:14:50 -0500 +From: Geoffrey +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: solutions for new Postgresql application testing +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.013 required=5 tests=[AWL=0.013] +X-Spam-Score: 0.013 +X-Spam-Level: +X-Archive-Number: 200511/6 +X-Sequence-Number: 15263 + +We are going live with a application in a few months that is a complete +rewrite of an existing application. We are moving from an existing +proprietary database to Postgresql. We are looking for some +insight/suggestions as to how folks test Postgresql in such a situation. + +We really want to run it throught the wringer before going live. I'm +throwing together a test suite that consists of mostly perl scripts. +I'm wondering what other, if any approaches folks have taken in a +similar situation. I know there's nothing like a real live test with +real users, and that will happen, but we want to do some semi-automated +load testing prior. + +Anyone ever use any profiling apps (gprof) with any success? + +We've got a failover cluster design and would like any insights here as +well. + +We're also trying to decide whether a single database with multiple +schemas or multiple databases are the best solution. We've done some +research on this through the archives, and the answer seems to depend on +the database/application design. Still, we welcome any generic ideas on +this issue as well. + +I've not provided any specifics on hardware or application as we really +want high level stuff at this time. + +Thanks for any pointers or suggestions. + +-- +Until later, Geoffrey + +From pgsql-performance-owner@postgresql.org Tue Nov 1 10:50:35 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 83D5BDA9C4 + for ; + Tue, 1 Nov 2005 10:50:32 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 68554-06 + for ; + Tue, 1 Nov 2005 14:50:28 +0000 (GMT) +Received: from mail1.npci.com (mail.npcinternational.com [63.76.154.140]) + by svr1.postgresql.org (Postfix) with ESMTP id 539F9DB6C3 + for ; + Tue, 1 Nov 2005 10:50:30 -0400 (AST) +Received: from fc63r41.npci.com ([172.16.0.131]) + by mail1.npci.com (MOS 3.5.9-GR) + with ESMTP id BXH01235 (AUTH via LOGINBEFORESMTP); + Tue, 1 Nov 2005 08:45:20 -0600 (CST) +Date: Tue, 1 Nov 2005 08:50:37 -0600 +From: Jon Brisbin +To: pgsql-performance@postgresql.org +Subject: Re: 8.1beta3 performance +Message-ID: <20051101085037.1b12b077@fc63r41.npci.com> +In-Reply-To: +References: +Organization: NPC International +X-Mailer: Sylpheed-Claws 1.9.13 (GTK+ 2.6.9; i386-portbld-freebsd6.0) +Mime-Version: 1.0 +Content-Type: text/plain; charset=US-ASCII +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.234 required=5 tests=[AWL=0.234] +X-Spam-Score: 0.234 +X-Spam-Level: +X-Archive-Number: 200511/7 +X-Sequence-Number: 15264 + +On Mon, 31 Oct 2005 17:16:46 -0600 +"PostgreSQL" wrote: + +> We're running 8.1beta3 on one server and are having ridiculous +> performance issues. This is a 2 cpu Opteron box and both processors +> are staying at 98 or 99% utilization processing not-that-complex +> queries. Prior to the upgrade, our I/O wait time was about 60% and +> cpu utilization rarely got very high, now I/O wait time is at or near +> zero. +> +> I'm planning to go back to 8.0 tonight or tomorrow night but thought +> I'd check the pqsql-performance prophets before I gave it up. + +I have a stock FreeBSD 5.4 box that I put 8.1 on last night. I ran +pgbench against it and my tps dropped from ~300tps in 8.0.3 to 20tps +in 8.1. That's right. 20. No changes in any system configuration. No +data in the new 8.1 database, only the pgbench init'ed stuff. 25 +clients, 100 and 1000 transactions with a scaling factor of 10, which +gives me 1,000,000 tuples to shoot through. + +I wiped out the 8.1 installation, put 8.0.4 in it's place, and +pgbenched it again. ~300tps again. + +It's not a problem with system configuration if 8.0 works fine, but 8.1 +has problems, unless there is something that 8.1 needs tweaked that 8.0 +doesn't. In that case, I just need to know what that is and I can tweak +it. + +Dual Xeon 2.6GB HTT PowerEdge, 4GB RAM, RAID 5 +FreeBSD 5.4 RELEASE, custom-compiled kernel +CFLAGS=-O3 -funroll-loops -pipe (also tried -O2, same difference) + +Jon Brisbin +Webmeister +NPC International, Inc. + +From pgsql-performance-owner@postgresql.org Tue Nov 1 11:37:36 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CEB0CDB654 + for ; + Tue, 1 Nov 2005 11:37:34 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 94923-03 + for ; + Tue, 1 Nov 2005 15:37:30 +0000 (GMT) +Received: from pop-cowbird.atl.sa.earthlink.net + (pop-cowbird.atl.sa.earthlink.net [207.69.195.68]) + by svr1.postgresql.org (Postfix) with ESMTP id 2E915DB631 + for ; + Tue, 1 Nov 2005 11:37:33 -0400 (AST) +Received: from elwamui-norfolk.atl.sa.earthlink.net ([209.86.224.43]) + by pop-cowbird.atl.sa.earthlink.net with esmtp (Exim 3.36 #10) + id 1EWyCd-0004TZ-00; Tue, 01 Nov 2005 10:37:35 -0500 +Message-ID: + <867256.1130859455220.JavaMail.root@elwamui-norfolk.atl.sa.earthlink.net> +Date: Tue, 1 Nov 2005 10:37:35 -0500 (GMT-05:00) +From: Ron Peacetree +Reply-To: Ron Peacetree +To: Kelly Burkhart , + pgsql-performance@postgresql.org +Subject: Re: 8.x index insert performance +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Mailer: EarthLink Zoo Mail 1.0 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.072 required=5 tests=[AWL=0.072] +X-Spam-Score: 0.072 +X-Spam-Level: +X-Archive-Number: 200511/8 +X-Sequence-Number: 15265 + +I'm surprised that no one seems to have yet suggested the following +simple experiment: + +Increase the RAM 4GB -> 8GB, tune for best performance, and +repeat your 100M row insert experiment. + +Does overall insert performance change? Does the performance +drop rows in still occur? Does it occur in ~ the same place? +Etc. + +If the effect does seem to be sensitive to the amount of RAM in the +server, it might be worth redoing the experiment(s) with 2GB and +16GB as well... + +ron + +-----Original Message----- +From: Kelly Burkhart +Sent: Oct 31, 2005 12:12 PM +To: pgsql-performance@postgresql.org +Subject: [PERFORM] 8.x index insert performance + +Greetings, + +We are running some performance tests in which we are attempting to +insert about 100,000,000 rows in a database at a sustained rate. About +50M rows in, our performance drops dramatically. + +This test is with data that we believe to be close to what we will +encounter in production. However in tests with purely generated, +sequential data, we did not notice this slowdown. I'm trying to figure +out what patterns in the "real" data may be causing us problems. + +I have log,data and indexes on separate LUNs on an EMC SAN. Prior to +slowdown, each partition is writing at a consistent rate. Index +partition is reading at a much lower rate. At the time of slowdown, +index partition read rate increases, all write rates decrease. CPU +utilization drops. + +The server is doing nothing aside from running the DB. It is a dual +opteron (dual core, looks like 4 cpus) with 4GB RAM. shared_buffers = +32768. fsync = off. Postgres version is 8.1.b4. OS is SuSE Enterprise +server 9. + +My leading hypothesis is that one indexed column may be leading to our +issue. The column in question is a varchar(12) column which is non-null +in about 2% of the rows. The value of this column is 5 characters which +are the same for every row, followed by a 7 character zero filled base +36 integer. Thus, every value of this field will be exactly 12 bytes +long, and will be substantially the same down to the last bytes. + +Could this pattern be pessimal for a postgresql btree index? I'm +running a test now to see if I can verify, but my runs take quite a long +time... + +If this sounds like an unlikely culprit how can I go about tracking down +the issue? + +Thanks, + +-K + +---------------------------(end of broadcast)--------------------------- +TIP 4: Have you searched our list archives? + + http://archives.postgresql.org + + +From pgsql-performance-owner@postgresql.org Tue Nov 1 11:49:50 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6B237DB6B2 + for ; + Tue, 1 Nov 2005 11:49:49 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 95306-07 + for ; + Tue, 1 Nov 2005 15:49:44 +0000 (GMT) +Received: from anchor-post-35.mail.demon.net (anchor-post-35.mail.demon.net + [194.217.242.85]) + by svr1.postgresql.org (Postfix) with ESMTP id D401CDB684 + for ; + Tue, 1 Nov 2005 11:49:45 -0400 (AST) +Received: from mailgate.vale-housing.co.uk ([194.217.48.34] + helo=vale-housing.co.uk) + by anchor-post-35.mail.demon.net with esmtp (Exim 4.42) + id 1EWyHs-000DuB-GW + for pgsql-performance@postgresql.org; Tue, 01 Nov 2005 15:43:06 +0000 +Received: from 84.13.26.127 ([84.13.26.127]) by ratbert.vale-housing.co.uk + ([192.168.1.106]) with Microsoft Exchange Server HTTP-DAV ; + Tue, 1 Nov 2005 15:49:15 +0000 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Tue, 01 Nov 2005 15:49:14 +0000 +Subject: Re: 8.1beta3 performance +From: Dave Page +To: Jon Brisbin , + +Message-ID: +Thread-Topic: [PERFORM] 8.1beta3 performance +Thread-Index: AcXe+87xDZdLP0rvEdqyyQARJHpWaA== +In-Reply-To: <20051101085037.1b12b077@fc63r41.npci.com> +Mime-version: 1.0 +Content-type: text/plain; + charset="US-ASCII" +Content-transfer-encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.388 required=5 tests=[AWL=0.135, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.388 +X-Spam-Level: * +X-Archive-Number: 200511/9 +X-Sequence-Number: 15266 + + + + +On 1/11/05 2:50 pm, "Jon Brisbin" wrote: + +> On Mon, 31 Oct 2005 17:16:46 -0600 +> "PostgreSQL" wrote: +> +>> We're running 8.1beta3 on one server and are having ridiculous +>> performance issues. This is a 2 cpu Opteron box and both processors +>> are staying at 98 or 99% utilization processing not-that-complex +>> queries. Prior to the upgrade, our I/O wait time was about 60% and +>> cpu utilization rarely got very high, now I/O wait time is at or near +>> zero. +>> +>> I'm planning to go back to 8.0 tonight or tomorrow night but thought +>> I'd check the pqsql-performance prophets before I gave it up. +> +> I have a stock FreeBSD 5.4 box that I put 8.1 on last night. I ran +> pgbench against it and my tps dropped from ~300tps in 8.0.3 to 20tps +> in 8.1. That's right. 20. No changes in any system configuration. No +> data in the new 8.1 database, only the pgbench init'ed stuff. 25 +> clients, 100 and 1000 transactions with a scaling factor of 10, which +> gives me 1,000,000 tuples to shoot through. +> +> I wiped out the 8.1 installation, put 8.0.4 in it's place, and +> pgbenched it again. ~300tps again. +> +> It's not a problem with system configuration if 8.0 works fine, but 8.1 +> has problems, unless there is something that 8.1 needs tweaked that 8.0 +> doesn't. In that case, I just need to know what that is and I can tweak +> it. + +Hi Jon, + +Did you run the bundled version of pgbench against it's own installation? +There we some changes to pgbench for 8.1, and I have to wonder (bearing in +mind I haven't really looked at them) whether they could be affecting things +in any way. Do you get comparable results running the 8.0 pgbench against +both server versions? + +Regards, Dave + + + +From pgsql-performance-owner@postgresql.org Tue Nov 1 13:25:10 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 91A36DB6CB + for ; + Tue, 1 Nov 2005 13:25:08 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 80423-10 + for ; + Tue, 1 Nov 2005 17:24:53 +0000 (GMT) +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id EAECADB6A4 + for ; + Tue, 1 Nov 2005 13:24:52 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA1HOheB026530; + Tue, 1 Nov 2005 12:24:43 -0500 (EST) +To: Jon Brisbin +Cc: pgsql-performance@postgresql.org +Subject: Re: 8.1beta3 performance +In-reply-to: <20051101085037.1b12b077@fc63r41.npci.com> +References: + <20051101085037.1b12b077@fc63r41.npci.com> +Comments: In-reply-to Jon Brisbin + message dated "Tue, 01 Nov 2005 08:50:37 -0600" +Date: Tue, 01 Nov 2005 12:24:43 -0500 +Message-ID: <26529.1130865883@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/10 +X-Sequence-Number: 15267 + +Jon Brisbin writes: +> I have a stock FreeBSD 5.4 box that I put 8.1 on last night. I ran +> pgbench against it and my tps dropped from ~300tps in 8.0.3 to 20tps +> in 8.1. That's right. 20. No changes in any system configuration. + +You sure about that last? These numbers are kind of consistent with the +idea that fsync is off in the 8.0 database and on in the 8.1 database. + +Using the same test case you mention (pgbench -s 10, -c 25 -t 1000), +I find that 8.1 is a bit faster than 8.0, eg + +8.1 fsync off: +tps = 89.831186 (including connections establishing) +tps = 89.865065 (excluding connections establishing) + +8.1 fsync on: +tps = 74.865078 (including connections establishing) +tps = 74.889066 (excluding connections establishing) + +8.0 fsync off: +tps = 80.271338 (including connections establishing) +tps = 80.302054 (excluding connections establishing) + +8.0 fsync on: +tps = 67.405708 (including connections establishing) +tps = 67.426546 (excluding connections establishing) + +(All database parameters are defaults except fsync.) + +These numbers are with assert-enabled builds, on a cheap PC whose drive +lies about write-complete, so they're not very representative of the +real world I suppose. But I'm sure not seeing any 10x degradation. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Tue Nov 1 15:00:31 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5FDCEDB70A + for ; + Tue, 1 Nov 2005 15:00:29 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 50027-08 + for ; + Tue, 1 Nov 2005 19:00:18 +0000 (GMT) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id D9390DB70E + for ; + Tue, 1 Nov 2005 15:00:17 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: improvise callbacks in plpgsql +Date: Tue, 1 Nov 2005 14:00:00 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD754@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: improvise callbacks in plpgsql +Thread-Index: AcXfFnVc2Rgg/SN8R1qNBfDbkPYJtA== +From: "Merlin Moncure" +To: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.048 required=5 tests=[AWL=0.048] +X-Spam-Score: 0.048 +X-Spam-Level: +X-Archive-Number: 200511/11 +X-Sequence-Number: 15268 + +hello performance minded administrators: + +We have recently converted a number of routines that walk a bill of +materials (which is a nested structure) from the application side to the +server side via recursive plpgsql functions. The performance is +absolutely fantastic but I have to maintain a specialized 'walker' for +each specific task that I have to do. It would be very nice and elegant +if I could pass in the function for the walker to execute while it is +iterating through the bill of materials. I have been beating my head +against the wall for the best way to do this so here I am shopping for +ideas. + +A simplified idealized version of what I would like to do is=20 + begin + select (callback_routine)(record_type) + end; + +from within a plpgsql function. I am borrowing the C syntax for a +function pointer here. The problem I am running into is the only way to +do callbacks is via dynamic sql...however you can use higher level types +such as row/record type in dynamic sql (at least not efficiently). I +could of course make a full dynamic sql call by expanding the record +type into a large parameter list but this is unwieldy and brittle. + +Any thoughts? + +Merlin + +From pgsql-performance-owner@postgresql.org Tue Nov 1 15:39:43 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 11097DB15F + for ; + Tue, 1 Nov 2005 15:39:40 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 81931-09 + for ; + Tue, 1 Nov 2005 19:39:38 +0000 (GMT) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 4097FDB0A8 + for ; + Tue, 1 Nov 2005 15:39:37 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: solutions for new Postgresql application testing +Date: Tue, 1 Nov 2005 14:39:38 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD759@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] solutions for new Postgresql application testing +Thread-Index: AcXe7wWehAxUwKokQzKAaFnhSWI4swAKE92w +From: "Merlin Moncure" +To: "Geoffrey" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.047 required=5 tests=[AWL=0.047] +X-Spam-Score: 0.047 +X-Spam-Level: +X-Archive-Number: 200511/12 +X-Sequence-Number: 15269 + +Geoffrey wrote: +> We are going live with a application in a few months that is a +complete +> rewrite of an existing application. We are moving from an existing +> proprietary database to Postgresql. We are looking for some +> insight/suggestions as to how folks test Postgresql in such a +situation. + +Shouldn't you run your tests *before* rewriting your application? :). +You don't have to answer that. + +> We're also trying to decide whether a single database with multiple +> schemas or multiple databases are the best solution. We've done some +> research on this through the archives, and the answer seems to depend +on +> the database/application design. Still, we welcome any generic ideas +on +> this issue as well. + +I can help a little bit here. Yes, this decision will be heavily +influenced by application design. Let's assume you have to keep +multiple identical table sets (suppose you have multiple companies on +the same server for example). Here are some general stipulations: + +Reasons to use schemas: +* If you have a requirement where data must be queried from multiple +data stores at the same time, or between various data stores and a +shared area, this argues for schemas. While it is possible to do this +without schemas via dblink, which is the postgresql inter-database rpc, +performance can be an issue and there is some overhead of setting it up. + +* If you need to swap out data stores on the fly without reconnecting, +then this argues strongly in favor of schemas. With schemas, you can +manipulate which datastore you are using by simply manipulating the +search_path. There is one big caveat to this: your non dynamic pl/pgsql +functions will stick to the tables they use following the first time you +run them like suction cups. Worse, your sql functions will stick to the +tables they refer to when compiled, making non-immutable sql functions a +no-no in a multi-schema environment. However, there is a clever +workaround to this by force recompiling you pl/pgsql functions (search +the recent archives on this list). + +* Finally, since multiple schemas can share a common public area, this +means that if you have to deploy database features that apply to all of +your datastores, you can sometimes get away with sticking them in a +public area of the databse...server side utility functions are an +example of this. + +Reasons to use databases: +* Certain third party tools may have trouble with schemas. + +* Manipulating the search path can be error prone and relatively +tedious. + +* Database are more fully separate. I run multi schema, and I make +heavy use of the userlock contrib module. This means I have to take +special care not to have inter-schema overlap of my lock identifier. +There are other cases where this might bite you, for example if you +wanted one data store to respond to notifications but not another. +These are solvable problems, but can be a headache. + +In short, there are pros and cons either way. If it's any help, the +servers I administrate, which have *really complex* data interdependency +and isolation requirements, use schemas for the extra flexibility. + +Merlin + +From pgsql-performance-owner@postgresql.org Tue Nov 1 17:29:24 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B7F96DB735 + for ; + Tue, 1 Nov 2005 17:29:22 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 44368-02 + for ; + Tue, 1 Nov 2005 21:29:20 +0000 (GMT) +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 4F359DB733 + for ; + Tue, 1 Nov 2005 17:29:21 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA1LTNle028344; + Tue, 1 Nov 2005 16:29:23 -0500 (EST) +To: "Merlin Moncure" +Cc: pgsql-performance@postgresql.org +Subject: Re: improvise callbacks in plpgsql +In-reply-to: <6EE64EF3AB31D5448D0007DD34EEB3417DD754@Herge.rcsinc.local> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD754@Herge.rcsinc.local> +Comments: In-reply-to "Merlin Moncure" + message dated "Tue, 01 Nov 2005 14:00:00 -0500" +Date: Tue, 01 Nov 2005 16:29:22 -0500 +Message-ID: <28343.1130880562@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/13 +X-Sequence-Number: 15270 + +"Merlin Moncure" writes: +> A simplified idealized version of what I would like to do is +> begin +> select (callback_routine)(record_type) +> end; +> from within a plpgsql function. I am borrowing the C syntax for a +> function pointer here. + +Well, there's no function pointer type in SQL :-(. I don't see any way +to do what you want in pure plpgsql. If you're willing to implement an +auxiliary C function you could probably make it go: + + create function callit(oid, record) returns void ... + +where the OID has to be the OID of a function taking a record-type +argument. The regprocedure pseudotype would allow you not to need +to write any numeric OIDs in your code: + + select callit('myfunc(record)'::regprocedure, recordvar); + +The body of callit() need be little more than OidFunctionCall1() +plus whatever error checking and security checking you want to +include. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Tue Nov 1 18:13:52 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 7B699DB1B9 + for ; + Tue, 1 Nov 2005 18:13:50 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 56675-10 + for ; + Tue, 1 Nov 2005 22:13:47 +0000 (GMT) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 00C50DB165 + for ; + Tue, 1 Nov 2005 18:13:48 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: improvise callbacks in plpgsql +Date: Tue, 1 Nov 2005 17:13:48 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD767@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] improvise callbacks in plpgsql +Thread-Index: AcXfK1UD9TahUbk7Rl+KStGUxj01mAABbwKQ +From: "Merlin Moncure" +To: "Tom Lane" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.047 required=5 tests=[AWL=0.047] +X-Spam-Score: 0.047 +X-Spam-Level: +X-Archive-Number: 200511/14 +X-Sequence-Number: 15271 + +> The body of callit() need be little more than OidFunctionCall1() +> plus whatever error checking and security checking you want to +> include. + +esp=3D# create table test(f text); +CREATE TABLE + +esp=3D# create function test() returns void as=20 +$$=20 + begin=20 + insert into test values ('called');=20 + end;=20 +$$ language plpgsql; + +esp=3D# create or replace function test2() returns void as +esp-# $$ +esp$# declare +esp$# r record; +esp$# begin +esp$# select into r 'abc'; +esp$# perform callit('test()'::regprocedure, r); +esp$# end; +esp$# +esp$# $$ language plpgsql; +CREATE FUNCTION + +esp=3D# select test2(); + +esp=3D# select * from test; + f +-------- + called +(1 row) + +one word... +w00t + +Merlin + +From pgsql-performance-owner@postgresql.org Tue Nov 1 19:04:43 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8AAECDB72E + for ; + Tue, 1 Nov 2005 19:04:39 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 24173-03 + for ; + Tue, 1 Nov 2005 23:04:36 +0000 (GMT) +Received: from flake.decibel.org (flake.decibel.org [67.100.216.10]) + by svr1.postgresql.org (Postfix) with ESMTP id 9AA11DB722 + for ; + Tue, 1 Nov 2005 19:04:37 -0400 (AST) +Received: by flake.decibel.org (Postfix, from userid 1001) + id 7843915257; Tue, 1 Nov 2005 17:04:40 -0600 (CST) +Date: Tue, 1 Nov 2005 17:04:40 -0600 +From: "Jim C. Nasby" +To: Merlin Moncure +Cc: Tom Lane , pgsql-performance@postgresql.org +Subject: Re: improvise callbacks in plpgsql +Message-ID: <20051101230440.GU20349@pervasive.com> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD767@Herge.rcsinc.local> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <6EE64EF3AB31D5448D0007DD34EEB3417DD767@Herge.rcsinc.local> +X-Operating-System: FreeBSD 4.11-RELEASE-p10 i386 +X-Distributed: Join the Effort! http://www.distributed.net +User-Agent: Mutt/1.5.9i +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.007 required=5 tests=[AWL=0.007] +X-Spam-Score: 0.007 +X-Spam-Level: +X-Archive-Number: 200511/15 +X-Sequence-Number: 15272 + +Would you be willing to write up an example of this? We often get asked +about support for WITH, so I bet there's other people who would be very +interested in what you've got. + +On Tue, Nov 01, 2005 at 05:13:48PM -0500, Merlin Moncure wrote: +> > The body of callit() need be little more than OidFunctionCall1() +> > plus whatever error checking and security checking you want to +> > include. +> +> esp=# create table test(f text); +> CREATE TABLE +> +> esp=# create function test() returns void as +> $$ +> begin +> insert into test values ('called'); +> end; +> $$ language plpgsql; +> +> esp=# create or replace function test2() returns void as +> esp-# $$ +> esp$# declare +> esp$# r record; +> esp$# begin +> esp$# select into r 'abc'; +> esp$# perform callit('test()'::regprocedure, r); +> esp$# end; +> esp$# +> esp$# $$ language plpgsql; +> CREATE FUNCTION +> +> esp=# select test2(); +> +> esp=# select * from test; +> f +> -------- +> called +> (1 row) +> +> one word... +> w00t +> +> Merlin +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 5: don't forget to increase your free space map settings +> + +-- +Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com +Pervasive Software http://pervasive.com work: 512-231-6117 +vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 + +From pgsql-performance-owner@postgresql.org Tue Nov 1 19:12:29 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B5CD7DB72F + for ; + Tue, 1 Nov 2005 19:12:27 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 25607-04 + for ; + Tue, 1 Nov 2005 23:12:24 +0000 (GMT) +Received: from www.3times25.net (duck.3times25.net [66.23.211.34]) + by svr1.postgresql.org (Postfix) with ESMTP id 3E3C1DB729 + for ; + Tue, 1 Nov 2005 19:12:26 -0400 (AST) +Received: from [127.0.0.1] (localhost [127.0.0.1]) + by www.3times25.net (Postfix) with ESMTP id 25C16DB92C + for ; + Tue, 1 Nov 2005 18:12:37 -0500 (EST) +Message-ID: <4367F664.1010709@3times25.net> +Date: Tue, 01 Nov 2005 18:12:36 -0500 +From: Geoffrey +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: solutions for new Postgresql application testing +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD759@Herge.rcsinc.local> +In-Reply-To: <6EE64EF3AB31D5448D0007DD34EEB3417DD759@Herge.rcsinc.local> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.013 required=5 tests=[AWL=0.013] +X-Spam-Score: 0.013 +X-Spam-Level: +X-Archive-Number: 200511/16 +X-Sequence-Number: 15273 + +Merlin Moncure wrote: +> Geoffrey wrote: +> +>>We are going live with a application in a few months that is a complete +>>rewrite of an existing application. We are moving from an existing +>>proprietary database to Postgresql. We are looking for some +>>insight/suggestions as to how folks test Postgresql in such a situation. +> +> Shouldn't you run your tests *before* rewriting your application? :). +> You don't have to answer that. + +The logic has been proven. What we want to really test is loading and +the remote possibility that the compiler built code based on what we +wrote, rather then what we thought. :) + +>>We're also trying to decide whether a single database with multiple +>>schemas or multiple databases are the best solution. We've done some +>>research on this through the archives, and the answer seems to depend on +>>the database/application design. Still, we welcome any generic ideas +>>on this issue as well. +> +> I can help a little bit here. Yes, this decision will be heavily +> influenced by application design. Let's assume you have to keep +> multiple identical table sets (suppose you have multiple companies on +> the same server for example). Here are some general stipulations: + + + +Thanks muchly for your insights. Just the kind of info we're looking +for. Now if I could only find that mind reading compiler. + +We lean towards multiple databases when thinking about the possible need +to bring down a single database without affecting the others. We do +require access to multiple datastores, but that is relatively easily +done with either schemas or databases with perl and C, which are our +tools of choice. These databases are pretty much identical in design, +simply for different 'parts' of the business. + +Any further thoughts are, of course, still welcome. + +-- +Until later, Geoffrey + +From pgsql-performance-owner@postgresql.org Tue Nov 1 19:16:58 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 46AB5DB641 + for ; + Tue, 1 Nov 2005 19:16:58 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 28103-07 + for ; + Tue, 1 Nov 2005 23:16:55 +0000 (GMT) +Received: from xproxy.gmail.com (xproxy.gmail.com [66.249.82.205]) + by svr1.postgresql.org (Postfix) with ESMTP id DCFB8DB62B + for ; + Tue, 1 Nov 2005 19:16:56 -0400 (AST) +Received: by xproxy.gmail.com with SMTP id s14so1385291wxc + for ; + Tue, 01 Nov 2005 15:16:59 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; + b=T56u6rc33hcMXRnQMaqH0YBbM0M7CrCESW3R4uKzWTYpBejvVVtrBE/ssp9RaEpCcOpnWyZ3bIoxGSbAdmhvIT4XBFqBryTACGDEwZ/v/UkswULRVrZKV5O+auFeG6/a7yaDbvRmF7LiVbOidlonxmlcjB87bsN8h19FrPslKsc= +Received: by 10.70.42.15 with SMTP id p15mr2792127wxp; + Tue, 01 Nov 2005 15:16:59 -0800 (PST) +Received: by 10.70.132.7 with HTTP; Tue, 1 Nov 2005 15:16:59 -0800 (PST) +Message-ID: <330532b60511011516u3709d826w391a4ac167c6967b@mail.gmail.com> +Date: Tue, 1 Nov 2005 18:16:59 -0500 +From: Mitch Pirtle +To: "pgsql-performance@postgresql.org" +Subject: Joining views disables indexes? +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.079 required=5 tests=[AWL=0.079] +X-Spam-Score: 0.079 +X-Spam-Level: +X-Archive-Number: 200511/17 +X-Sequence-Number: 15274 + +I have a client that is testing an internal data platform, and they +were happy with PostgreSQL until they tried to join views - at that +time they discovered PostgreSQL was not using the indexes, and the +queries took 24 hours to execute as a result. + +Is this a known issue, or is this possibly a site-specific problem? + +They just implemented the exact same datamodel in MySQL 5.0, with +views and InnoDB tables, and performance is still subsecond. + +Would love to know if this is a known issue. + +-- Mitch + +From pgsql-performance-owner@postgresql.org Tue Nov 1 19:23:14 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id BA813DB704 + for ; + Tue, 1 Nov 2005 19:23:13 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 28631-08 + for ; + Tue, 1 Nov 2005 23:23:11 +0000 (GMT) +Received: from flake.decibel.org (flake.decibel.org [67.100.216.10]) + by svr1.postgresql.org (Postfix) with ESMTP id 7D192DB6BE + for ; + Tue, 1 Nov 2005 19:23:12 -0400 (AST) +Received: by flake.decibel.org (Postfix, from userid 1001) + id EF44115257; Tue, 1 Nov 2005 17:23:14 -0600 (CST) +Date: Tue, 1 Nov 2005 17:23:14 -0600 +From: "Jim C. Nasby" +To: Mitch Pirtle +Cc: "pgsql-performance@postgresql.org" +Subject: Re: Joining views disables indexes? +Message-ID: <20051101232314.GV20349@pervasive.com> +References: <330532b60511011516u3709d826w391a4ac167c6967b@mail.gmail.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <330532b60511011516u3709d826w391a4ac167c6967b@mail.gmail.com> +X-Operating-System: FreeBSD 4.11-RELEASE-p10 i386 +X-Distributed: Join the Effort! http://www.distributed.net +User-Agent: Mutt/1.5.9i +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.007 required=5 tests=[AWL=0.007] +X-Spam-Score: 0.007 +X-Spam-Level: +X-Archive-Number: 200511/18 +X-Sequence-Number: 15275 + +On Tue, Nov 01, 2005 at 06:16:59PM -0500, Mitch Pirtle wrote: +> I have a client that is testing an internal data platform, and they +> were happy with PostgreSQL until they tried to join views - at that +> time they discovered PostgreSQL was not using the indexes, and the +> queries took 24 hours to execute as a result. +> +> Is this a known issue, or is this possibly a site-specific problem? +> +> They just implemented the exact same datamodel in MySQL 5.0, with +> views and InnoDB tables, and performance is still subsecond. +> +> Would love to know if this is a known issue. + +Views simply get expanded to a full query, so the views have nothing to +do with it. + +Make sure that they've run analyze on the entire database. Upping +default_statistics_target to 100 is probably a good idea as well. + +If that doesn't work, get an explain analyze of the query and post it +here. You can try posting just an explain, but that's much less useful. +-- +Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com +Pervasive Software http://pervasive.com work: 512-231-6117 +vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 + +From pgsql-performance-owner@postgresql.org Tue Nov 1 19:28:05 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id ECACEDB62B + for ; + Tue, 1 Nov 2005 19:28:03 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 34024-01 + for ; + Tue, 1 Nov 2005 23:28:00 +0000 (GMT) +Received: from cassarossa.samfundet.no (cassarossa.samfundet.no + [129.241.93.19]) + by svr1.postgresql.org (Postfix) with ESMTP id 8881EDB53D + for ; + Tue, 1 Nov 2005 19:28:01 -0400 (AST) +Received: from trofast.sesse.net ([129.241.93.32]) + by cassarossa.samfundet.no with esmtp (Exim 4.50) + id 1EX5Xu-00036E-27; Wed, 02 Nov 2005 00:28:03 +0100 +Received: from sesse by trofast.sesse.net with local (Exim 3.36 #1 (Debian)) + id 1EX5Y8-00041j-00; Wed, 02 Nov 2005 00:28:16 +0100 +Date: Wed, 2 Nov 2005 00:28:16 +0100 +From: "Steinar H. Gunderson" +To: Mitch Pirtle +Cc: "pgsql-performance@postgresql.org" +Subject: Re: Joining views disables indexes? +Message-ID: <20051101232816.GA15321@uio.no> +Mail-Followup-To: Mitch Pirtle , + "pgsql-performance@postgresql.org" +References: <330532b60511011516u3709d826w391a4ac167c6967b@mail.gmail.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=utf-8 +Content-Disposition: inline +In-Reply-To: <330532b60511011516u3709d826w391a4ac167c6967b@mail.gmail.com> +X-Operating-System: Linux 2.6.14-rc5 on a x86_64 +X-Message-Flag: Outlook? --> http://www.mozilla.org/products/thunderbird/ +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.009 required=5 tests=[AWL=0.009] +X-Spam-Score: 0.009 +X-Spam-Level: +X-Archive-Number: 200511/19 +X-Sequence-Number: 15276 + +On Tue, Nov 01, 2005 at 06:16:59PM -0500, Mitch Pirtle wrote: +> I have a client that is testing an internal data platform, and they +> were happy with PostgreSQL until they tried to join views - at that +> time they discovered PostgreSQL was not using the indexes, and the +> queries took 24 hours to execute as a result. +> +> Is this a known issue, or is this possibly a site-specific problem? + +This is way too general to give a good solution. In general, PostgreSQL +should have no problem using indexes on joins (in versions before 8.0, there +was a problem using indexes on joins of differing data types, though). +This does of course assume that its statistics are good; I assume you've +doing ANALYZE on the database after loading the database? + +What you want to do is to post your table definitions and EXPLAIN ANALYZE +output of a slow query; that could be difficult if it takes 24 hours, though, +so you might try a slightly quicker query for starters. + +/* Steinar */ +-- +Homepage: http://www.sesse.net/ + +From pgsql-performance-owner@postgresql.org Tue Nov 1 19:28:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id F047FDB706 + for ; + Tue, 1 Nov 2005 19:28:44 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 34047-02 + for ; + Tue, 1 Nov 2005 23:28:42 +0000 (GMT) +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id A46E2DB724 + for ; + Tue, 1 Nov 2005 19:28:43 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA1NSiWh029381; + Tue, 1 Nov 2005 18:28:44 -0500 (EST) +To: Mitch Pirtle +Cc: "pgsql-performance@postgresql.org" +Subject: Re: Joining views disables indexes? +In-reply-to: <330532b60511011516u3709d826w391a4ac167c6967b@mail.gmail.com> +References: <330532b60511011516u3709d826w391a4ac167c6967b@mail.gmail.com> +Comments: In-reply-to Mitch Pirtle + message dated "Tue, 01 Nov 2005 18:16:59 -0500" +Date: Tue, 01 Nov 2005 18:28:44 -0500 +Message-ID: <29380.1130887724@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/20 +X-Sequence-Number: 15277 + +Mitch Pirtle writes: +> I have a client that is testing an internal data platform, and they +> were happy with PostgreSQL until they tried to join views - at that +> time they discovered PostgreSQL was not using the indexes, and the +> queries took 24 hours to execute as a result. + +You'll need to provide some actual details if you want useful comments. +Let's see the table schemas, the view definitions, and the EXPLAIN plan +(I'll spare you a request for EXPLAIN ANALYZE given that it'd take 24 +hours to get ;-) ... although some estimate of the number of rows +expected would be helpful). And I trust they remembered to ANALYZE the +underlying tables first? Also, which PG version exactly? + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Tue Nov 1 21:19:27 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 52EF4DA827 + for ; + Tue, 1 Nov 2005 21:19:26 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 79927-10 + for ; + Wed, 2 Nov 2005 01:19:22 +0000 (GMT) +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 40740D783D + for ; + Tue, 1 Nov 2005 21:19:24 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id 85F8A30EC7; Wed, 2 Nov 2005 02:19:27 +0100 (MET) +From: "Qingqing Zhou" +X-Newsgroups: pgsql.performance +Subject: Re: performance of implicit join vs. explicit conditions on inet + queries? +Date: Tue, 1 Nov 2005 20:19:37 -0500 +Organization: Hub.Org Networking Services +Lines: 30 +Message-ID: +References: <20051024035809.GA18261@edmonds.ath.cx> + <29864.1130768650@sss.pgh.pa.us> +X-Complaints-To: usenet@news.hub.org +X-Priority: 3 +X-MSMail-Priority: Normal +X-Newsreader: Microsoft Outlook Express 6.00.2900.2180 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 +X-RFC2646: Format=Flowed; Original +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.573 required=5 tests=[AWL=0.573] +X-Spam-Score: 0.573 +X-Spam-Level: +X-Archive-Number: 200511/21 +X-Sequence-Number: 15278 + + +"Tom Lane" wrote +> +> No, that's completely irrelevant to his problem. The reason we can't do +> this is that the transformation from "x << const" to a range check on x +> is a plan-time transformation; there's no mechanism in place to do it +> at runtime. This is not easy to fix, because the mechanism that's doing +> it is primarily intended for LIKE/regex index optimization, and in that +> case a runtime pattern might well not be optimizable at all. +> + +Not quite understand, sorry ... + +(1) For this query (in an as-is PG syntax, which find out all rectangles lie +in a given rectangle) : + +SELECT r FROM all_rectangles + WHERE r << rectangle('(1,9),(9,1)'); + +If there is a GiST/Rtree index associated with all_rectangles.r, how do +optimizer estimate the cost to decide that we should use this index or +not(then by a seqscan)? + +(2) Does your above explaination mean that we can't use GiST for a spatial +join operation? + +Regards, +Qingqing + + + +From pgsql-performance-owner@postgresql.org Wed Nov 2 00:20:56 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8F96DD6822 + for ; + Wed, 2 Nov 2005 00:20:55 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 48324-10 + for ; + Wed, 2 Nov 2005 04:20:54 +0000 (GMT) +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 17952D680A + for ; + Wed, 2 Nov 2005 00:20:53 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA24Kqu8001208; + Tue, 1 Nov 2005 23:20:52 -0500 (EST) +To: "Qingqing Zhou" +Cc: pgsql-performance@postgresql.org +Subject: Re: performance of implicit join vs. explicit conditions on inet + queries? +In-reply-to: +References: <20051024035809.GA18261@edmonds.ath.cx> + <29864.1130768650@sss.pgh.pa.us> + +Comments: In-reply-to "Qingqing Zhou" + message dated "Tue, 01 Nov 2005 20:19:37 -0500" +Date: Tue, 01 Nov 2005 23:20:52 -0500 +Message-ID: <1207.1130905252@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/22 +X-Sequence-Number: 15279 + +"Qingqing Zhou" writes: +> "Tom Lane" wrote +>> No, that's completely irrelevant to his problem. The reason we can't do +>> this is that the transformation from "x << const" to a range check on x +>> is a plan-time transformation; there's no mechanism in place to do it +>> at runtime. + +> Not quite understand, sorry ... + +> (1) For this query (in an as-is PG syntax, which find out all rectangles lie +> in a given rectangle) : + +> SELECT r FROM all_rectangles +> WHERE r << rectangle('(1,9),(9,1)'); + +No, you're thinking of the wrong << operator. The question was about +the inet network inclusion operator. We have a special case in +indxpath.c to transform "inetcol << inetconstant" into a range check +on the inet variable, much like we can transform a left-anchored LIKE +pattern into a range check on the text variable. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Wed Nov 2 05:32:57 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id C0D5CD6842 + for ; + Wed, 2 Nov 2005 05:32:55 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 59306-06 + for ; + Wed, 2 Nov 2005 09:32:53 +0000 (GMT) +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id BFBB5D6819 + for ; + Wed, 2 Nov 2005 05:32:53 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id 45A4E31058; Wed, 2 Nov 2005 10:32:54 +0100 (MET) +From: "PostgreSQL" +X-Newsgroups: pgsql.performance +Subject: Re: 8.1beta3 performance +Date: Wed, 2 Nov 2005 03:32:45 -0600 +Organization: Hub.Org Networking Services +Lines: 49 +Message-ID: +References: + <20051101085037.1b12b077@fc63r41.npci.com> + <26529.1130865883@sss.pgh.pa.us> +X-Complaints-To: usenet@news.hub.org +X-Priority: 3 +X-MSMail-Priority: Normal +X-Newsreader: Microsoft Outlook Express 6.00.2900.2670 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2670 +X-RFC2646: Format=Flowed; Original +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/23 +X-Sequence-Number: 15280 + +I'm seeing some other little oddities in the beta as well. I'm watching an +ALTER TABLE ADD COLUMN right now that has been running almost two hours. I +stopped it the first time at 1 hour; I suppose I'll let it go this time and +see if it ever completes. The table is about 150K rows. Top, vmstat, and +iostat show almost no cpu or disk activity (1 to 3%) - it's as if it just +went to sleep. + +"Tom Lane" wrote in message +news:26529.1130865883@sss.pgh.pa.us... +> Jon Brisbin writes: +>> I have a stock FreeBSD 5.4 box that I put 8.1 on last night. I ran +>> pgbench against it and my tps dropped from ~300tps in 8.0.3 to 20tps +>> in 8.1. That's right. 20. No changes in any system configuration. +> +> You sure about that last? These numbers are kind of consistent with the +> idea that fsync is off in the 8.0 database and on in the 8.1 database. +> +> Using the same test case you mention (pgbench -s 10, -c 25 -t 1000), +> I find that 8.1 is a bit faster than 8.0, eg +> +> 8.1 fsync off: +> tps = 89.831186 (including connections establishing) +> tps = 89.865065 (excluding connections establishing) +> +> 8.1 fsync on: +> tps = 74.865078 (including connections establishing) +> tps = 74.889066 (excluding connections establishing) +> +> 8.0 fsync off: +> tps = 80.271338 (including connections establishing) +> tps = 80.302054 (excluding connections establishing) +> +> 8.0 fsync on: +> tps = 67.405708 (including connections establishing) +> tps = 67.426546 (excluding connections establishing) +> +> (All database parameters are defaults except fsync.) +> +> These numbers are with assert-enabled builds, on a cheap PC whose drive +> lies about write-complete, so they're not very representative of the +> real world I suppose. But I'm sure not seeing any 10x degradation. +> +> regards, tom lane +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 2: Don't 'kill -9' the postmaster +> + + + +From pgsql-performance-owner@postgresql.org Wed Nov 2 06:16:36 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 1A1F3D6878 + for ; + Wed, 2 Nov 2005 06:16:35 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 69336-07 + for ; + Wed, 2 Nov 2005 10:16:31 +0000 (GMT) +Received: from linuxworld.com.au (unknown [203.34.46.50]) + by svr1.postgresql.org (Postfix) with ESMTP id 9B333D6874 + for ; + Wed, 2 Nov 2005 06:16:30 -0400 (AST) +Received: from linuxworld.com.au (IDENT:swm@localhost.localdomain [127.0.0.1]) + by linuxworld.com.au (8.13.2/8.13.2) with ESMTP id jA2AGS2V014959; + Wed, 2 Nov 2005 21:16:28 +1100 +Received: from localhost (swm@localhost) + by linuxworld.com.au (8.13.2/8.13.2/Submit) with ESMTP id + jA2AGRkH014956; Wed, 2 Nov 2005 21:16:28 +1100 +X-Authentication-Warning: linuxworld.com.au: swm owned process doing -bs +Date: Wed, 2 Nov 2005 21:16:27 +1100 (EST) +From: Gavin Sherry +X-X-Sender: swm@linuxworld.com.au +To: Joost Kraaijeveld +Cc: Pgsql-Performance +Subject: Re: pgbench results interpretation? +In-Reply-To: <1130839542.3883.19.camel@Panoramix> +Message-ID: +References: <1130832189.21036.19.camel@Panoramix> + + <1130839542.3883.19.camel@Panoramix> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[AWL=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/24 +X-Sequence-Number: 15281 + +On Tue, 1 Nov 2005, Joost Kraaijeveld wrote: + +> Hi Gavin, +> +> Thanks for answering. +> +> On Tue, 2005-11-01 at 20:16 +1100, Gavin Sherry wrote: +> > On Tue, 1 Nov 2005, Joost Kraaijeveld wrote: +> > > 1. Is there a repository somewhere that shows results, using and +> > > documenting different kinds of hard- and software setups so that I can +> > > compare my results with someone elses? +> > +> > Other than the archives of this mailing list, no. +> OK. +> +> > > +> > > 2. Is there a reason for the difference in values from run-to-run of +> > > pgbench: +> > Well, firstly: pgbench is not a good benchmarking tool. +> Is there a reason why that is the case? I would like to understand why? +> Is it because the transaction is to small/large? Or that the queries are +> to small/large? Or just experience? +> +> > It is mostly used +> > to generate load. Secondly, the numbers are suspicious: do you have fsync +> > turned off? +> In the first trials I posted yes, in the second no. +> +> > Do you have write caching enabled? If so, you'd want to make +> > sure that cache is battery backed. +> I am aware of that, but for now, I am mostly interested in the effects +> of the configuration parameters. I won't do this at home ;-) + +Well, pgbench (tpc-b) suffers from inherent concurrency issues because all +connections are updating the branches table heavily. As an aside, did you +initialise with a scaling factor of 10 to match your level of concurrency? + +> +> +> > Thirdly, the effects of caching will be +> > seen on subsequent runs. +> In that case I would expect mostly rising values. I only copied and +> pasted 4 trials that were available in my xterm at the time of writing +> my email, but I could expand the list ad infinitum: the variance between +> the runs is very large. I also expect that if there is no shortage of +> memory wrt caching that the effect would be negligible, but I may be +> wrong. Part of using pgbench is learning about performance, not +> achieving it. + +Right. it is well known that performance with pgbench can vary wildly. I +usually get a lot less variation than you are getting. My point is though, +it's not a great indication of performance. I generally simulate the +real application running in production and test configuration changes with +that. The hackers list archive also contains links to the testing Mark +Wong has been doing at OSDL with TPC-C and TPC-H. Taking a look at the +configuration file he is using, along with the annotated postgresql.conf, +would be useful, depending on the load you're antipating and your +hardware. + +> +> > > 3. It appears that running more transactions with the same amount of +> > > clients leads to a drop in the transactions per second. I do not +> > > understand why this is (a drop from more clients I do understand). Is +> > > this because of the way pgbench works, the way PostgrSQL works or even +> > > Linux? +> > This degradation seems to suggest effects caused by the disk cache filling +> > up (assuming write caching is enabled) and checkpointing. +> Which diskcache are your referring to? The onboard harddisk or RAID5 +> controller caches or the OS cache? The first two I can unstand but if +> you refer to the OS cache I do not understand what I am seeing. I have +> enough memory giving the size of the database: during these duration (~) +> tests fsync was on, and the files could be loaded into memory easily +> (effective_cache_size = 32768 which is ~ 265 MB, the complete database +> directory 228 MB) + +Well, two things may be at play. 1) if you are using write caching on your +controller/disks then at the point at which that cache fills up +performance will degrade to roughly that you can expect if write through +cache was being used. Secondly, we checkpoint the system periodically to +ensure that recovery wont be too long a job. Running for pgbench for a few +seconds, you will not see the effect of checkpointing, which usually runs +once every 5 minutes. + +Hope this helps. + +Thanks, + +Gavin + +From pgsql-performance-owner@postgresql.org Wed Nov 2 09:36:59 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0332BD6868 + for ; + Wed, 2 Nov 2005 09:36:58 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 52025-01 + for ; + Wed, 2 Nov 2005 13:36:53 +0000 (GMT) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 53789D6806 + for ; + Wed, 2 Nov 2005 09:36:55 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: insert performance for win32 +Date: Wed, 2 Nov 2005 08:36:57 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD76C@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: insert performance for win32 +Thread-Index: AcXficvhooKyPjPFQyWN2fDRqzwFUwAJ7bRw +From: "Merlin Moncure" +To: "Marc Cousin" +Cc: , + "Qingqing Zhou" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.046 required=5 tests=[AWL=0.046] +X-Spam-Score: 0.046 +X-Spam-Level: +X-Archive-Number: 200511/25 +X-Sequence-Number: 15282 + +> I've done the tests with rc1. This is still as slow on windows ... +about +> 6-10 +> times slower thant linux (via Ip socket). (depending on using prepared +> queries, etc...) +>=20 +> By the way, we've tried to insert into the windows database from a +linux +> psql +> client, via the network. In this configuration, inserting is only +about 2 +> times slower than inserting locally (the linux client had a slower CPU +> 1700Mhz agains 3000). +> Could it be related to a problem in the windows psql client ? + +[OK, I'm bringing this back on-list, and bringing it to QingQing's +attention, who I secretly hope is the right person to be looking at this +problem :)] + +Just to recap Marc and I have been looking at the performance disparity +between windows and linux for a single transaction statement by +statement insert on a very narrow table with no keys from a remote +client. Marc's observations showed (and I verified) that windows is +much slower in this case than it should be. I gprof'ed both the psql +client and the server during the insert and didn't see anything +seriously out of order...unfortunately QQ's latest win32 performance +tweaks haven't helped. + +Marc's observation that by switching to a linux client drops time down +drastically is really intersing! + +Merlin + + + +From pgsql-performance-owner@postgresql.org Wed Nov 2 09:45:23 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 41952D82EB + for ; + Wed, 2 Nov 2005 09:45:06 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 53344-10 + for ; + Wed, 2 Nov 2005 13:45:00 +0000 (GMT) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id D8893D7D49 + for ; + Wed, 2 Nov 2005 09:44:59 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: improvise callbacks in plpgsql +Date: Wed, 2 Nov 2005 08:45:02 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD76D@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] improvise callbacks in plpgsql +Thread-Index: AcXfOKRHuQpQ7RcvTMmXKhyC8N16PgAd8XWA +From: "Merlin Moncure" +To: "Jim C. Nasby" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.046 required=5 tests=[AWL=0.046] +X-Spam-Score: 0.046 +X-Spam-Level: +X-Archive-Number: 200511/26 +X-Sequence-Number: 15283 + +> Would you be willing to write up an example of this? We often get +asked +> about support for WITH, so I bet there's other people who would be +very +> interested in what you've got. + +Sure. In fact, I had already decided this to be the next topic on my +blog. I'm assuming you are asking about tools to deal with recursive +sets in postgresql. A plpgsql solution is extremely fast, tight, and +easy if you do it right...Tom's latest suggestions (I have to flesh this +out some more) provide the missing piece puzzle to make it really tight +from a classic programming perspective. I don't miss the recursive +query syntax at all...IMO it's pretty much a hack anyways (to SQL). =20 + +Merlin + + + + +From pgsql-performance-owner@postgresql.org Wed Nov 2 09:54:16 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 95148D77B6 + for ; + Wed, 2 Nov 2005 09:54:15 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 54680-07 + for ; + Wed, 2 Nov 2005 13:54:10 +0000 (GMT) +Received: from mx-2.sollentuna.net (mx-2.sollentuna.net [195.84.163.199]) + by svr1.postgresql.org (Postfix) with ESMTP id 86A3CD774D + for ; + Wed, 2 Nov 2005 09:54:12 -0400 (AST) +Received: from ALGOL.sollentuna.se (janus.sollentuna.se [62.65.68.67]) + by mx-2.sollentuna.net (Postfix) with ESMTP + id E9FBB8F28E; Wed, 2 Nov 2005 14:54:14 +0100 (CET) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Subject: Re: insert performance for win32 +Date: Wed, 2 Nov 2005 14:54:14 +0100 +Message-ID: <6BCB9D8A16AC4241919521715F4D8BCE6C7B4A@algol.sollentuna.se> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +thread-index: AcXficvhooKyPjPFQyWN2fDRqzwFUwAJ7bRwAADR4FA= +From: "Magnus Hagander" +To: "Merlin Moncure" , + "Marc Cousin" +Cc: , + "Qingqing Zhou" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.034 required=5 tests=[AWL=0.034] +X-Spam-Score: 0.034 +X-Spam-Level: +X-Archive-Number: 200511/27 +X-Sequence-Number: 15284 + +> > I've done the tests with rc1. This is still as slow on windows ... +> about +> > 6-10 +> > times slower thant linux (via Ip socket). (depending on=20 +> using prepared=20 +> > queries, etc...) +> >=20 +> > By the way, we've tried to insert into the windows database from a +> linux +> > psql +> > client, via the network. In this configuration, inserting is only +> about 2 +> > times slower than inserting locally (the linux client had a=20 +> slower CPU=20 +> > 1700Mhz agains 3000). +> > Could it be related to a problem in the windows psql client ? +>=20 +> [OK, I'm bringing this back on-list, and bringing it to=20 +> QingQing's attention, who I secretly hope is the right person=20 +> to be looking at this problem :)] +>=20 +> Just to recap Marc and I have been looking at the performance=20 +> disparity between windows and linux for a single transaction=20 +> statement by statement insert on a very narrow table with no=20 +> keys from a remote client. Marc's observations showed (and I=20 +> verified) that windows is much slower in this case than it=20 +> should be. I gprof'ed both the psql client and the server=20 +> during the insert and didn't see anything seriously out of=20 +> order...unfortunately QQ's latest win32 performance tweaks=20 +> haven't helped. +>=20 +> Marc's observation that by switching to a linux client drops=20 +> time down drastically is really intersing! + +Could this be a case of the network being slow, as we've seen a couple +of times before? And if you run psql on the local box, you get it +double. + +Do you get a speed difference between the local windows box and a remote +wnidows box? + +//Magnus + +From pgsql-performance-owner@postgresql.org Wed Nov 2 10:41:14 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 96B98D8452 + for ; + Wed, 2 Nov 2005 10:41:12 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 74583-04 + for ; + Wed, 2 Nov 2005 14:41:09 +0000 (GMT) +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id E1713D830C + for ; + Wed, 2 Nov 2005 10:41:10 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA2EfEki005354; + Wed, 2 Nov 2005 09:41:14 -0500 (EST) +To: "PostgreSQL" +Cc: pgsql-performance@postgresql.org +Subject: Re: 8.1beta3 performance +In-reply-to: +References: + <20051101085037.1b12b077@fc63r41.npci.com> + <26529.1130865883@sss.pgh.pa.us> +Comments: In-reply-to "PostgreSQL" + message dated "Wed, 02 Nov 2005 03:32:45 -0600" +Date: Wed, 02 Nov 2005 09:41:14 -0500 +Message-ID: <5353.1130942474@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/28 +X-Sequence-Number: 15285 + +"PostgreSQL" writes: +> I'm seeing some other little oddities in the beta as well. I'm watching an +> ALTER TABLE ADD COLUMN right now that has been running almost two hours. I +> stopped it the first time at 1 hour; I suppose I'll let it go this time and +> see if it ever completes. The table is about 150K rows. Top, vmstat, and +> iostat show almost no cpu or disk activity (1 to 3%) - it's as if it just +> went to sleep. + +You sure it's not blocked on a lock? Check pg_locks ... if that sheds +no light, try attaching to the backend process with gdb and getting a +stack trace. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Wed Nov 2 10:41:58 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0222DD8BB0 + for ; + Wed, 2 Nov 2005 10:41:33 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 71037-10 + for ; + Wed, 2 Nov 2005 14:41:27 +0000 (GMT) +Received: from obelix.askesis.nl (laudanum.demon.nl [82.161.125.16]) + by svr1.postgresql.org (Postfix) with ESMTP id DEDBDD8A0B + for ; + Wed, 2 Nov 2005 10:41:27 -0400 (AST) +Received: obelix.askesis.nl 172.31.0.1 from 172.31.1.8 172.31.1.8 via HTTP + with MS-WebStorage 6.0.6249 +Received: from Panoramix by obelix.askesis.nl; 02 Nov 2005 15:41:31 +0100 +Subject: Re: pgbench results interpretation? +From: Joost Kraaijeveld +To: Gavin Sherry +Cc: Pgsql-Performance +In-Reply-To: +References: <1130832189.21036.19.camel@Panoramix> + + <1130839542.3883.19.camel@Panoramix> + +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Wed, 02 Nov 2005 15:41:31 +0100 +Message-Id: <1130942491.29028.57.camel@Panoramix> +Mime-Version: 1.0 +X-Mailer: Evolution 2.0.4 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.07 required=5 tests=[AWL=0.069, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.07 +X-Spam-Level: +X-Archive-Number: 200511/29 +X-Sequence-Number: 15286 + +On Wed, 2005-11-02 at 21:16 +1100, Gavin Sherry wrote: +> connections are updating the branches table heavily. As an aside, did you +> initialise with a scaling factor of 10 to match your level of concurrency? +Yep, I did. + + +> that. The hackers list archive also contains links to the testing Mark +> Wong has been doing at OSDL with TPC-C and TPC-H. Taking a look at the +> configuration file he is using, along with the annotated postgresql.conf, +> would be useful, depending on the load you're antipating and your +> hardware. +I will look into that project. + +> Well, two things may be at play. 1) if you are using write caching on your +> controller/disks then at the point at which that cache fills up +> performance will degrade to roughly that you can expect if write through +> cache was being used. Secondly, we checkpoint the system periodically to +> ensure that recovery wont be too long a job. Running for pgbench for a few +> seconds, you will not see the effect of checkpointing, which usually runs +> once every 5 minutes. +I still think it is strange. Simple tests with tar suggest that I could +easily do 600-700 tps at 50.000 KB/second ( as measured by iostat), a +test with bonnie++ measured throughputs > 40.000 KB/sec during very long +times, with 1723 - 2121 operations per second. These numbers suggest +that PostgreSQL is not using all it could from the hardware. Processor +load however is negligible during the pgbench tests. + +As written before, I will look into the OSDL benchmarks. Maybe they are +more suited for my needs: *understanding* performance determinators. + +> +> Hope this helps. +You certainly did, thanks. + +-- +Groeten, + +Joost Kraaijeveld +Askesis B.V. +Molukkenstraat 14 +6524NB Nijmegen +tel: 024-3888063 / 06-51855277 +fax: 024-3608416 +e-mail: J.Kraaijeveld@Askesis.nl +web: www.askesis.nl + + + +From pgsql-performance-owner@postgresql.org Wed Nov 2 10:47:29 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id EDB89D8A44 + for ; + Wed, 2 Nov 2005 10:47:27 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 78638-02 + for ; + Wed, 2 Nov 2005 14:47:23 +0000 (GMT) +Received: from mercure-2.sigma.fr (mercure-2.sigma.fr [195.25.81.10]) + by svr1.postgresql.org (Postfix) with ESMTP id 6DE65D8A0B + for ; + Wed, 2 Nov 2005 10:47:25 -0400 (AST) +Received: from localhost (localhost [127.0.0.1]) + by mercure-2.sigma.fr (Postfix) with ESMTP id ABED917FC9; + Wed, 2 Nov 2005 15:47:28 +0100 (CET) +Received: from mercure-2.sigma.fr ([127.0.0.1]) + by localhost (mercure-2 [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id 15661-02; Wed, 2 Nov 2005 15:47:28 +0100 (CET) +Received: from delpiv3000-124l (unknown [89.195.0.5]) + by mercure-2.sigma.fr (Postfix) with ESMTP id 7594017F7E; + Wed, 2 Nov 2005 15:47:28 +0100 (CET) +From: Marc Cousin +Organization: Sigma Informatique +To: "Magnus Hagander" +Subject: Re: insert performance for win32 +Date: Wed, 2 Nov 2005 15:47:28 +0100 +User-Agent: KMail/1.8.92 +Cc: "Merlin Moncure" , + pgsql-performance@postgresql.org, "Qingqing Zhou" +References: <6BCB9D8A16AC4241919521715F4D8BCE6C7B4A@algol.sollentuna.se> +In-Reply-To: <6BCB9D8A16AC4241919521715F4D8BCE6C7B4A@algol.sollentuna.se> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +Message-Id: <200511021547.28258.mcousin@sigma.fr> +X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at sigma.fr +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.905 required=5 tests=[AWL=-0.905, + RCVD_IN_WHOIS_BOGONS=1.811] +X-Spam-Score: 0.905 +X-Spam-Level: +X-Archive-Number: 200511/30 +X-Sequence-Number: 15287 + +Le Mercredi 02 Novembre 2005 14:54, Magnus Hagander a =E9crit=A0: +> > > I've done the tests with rc1. This is still as slow on windows ... +> > +> > about +> > +> > > 6-10 +> > > times slower thant linux (via Ip socket). (depending on +> > +> > using prepared +> > +> > > queries, etc...) +> > > +> > > By the way, we've tried to insert into the windows database from a +> > +> > linux +> > +> > > psql +> > > client, via the network. In this configuration, inserting is only +> > +> > about 2 +> > +> > > times slower than inserting locally (the linux client had a +> > +> > slower CPU +> > +> > > 1700Mhz agains 3000). +> > > Could it be related to a problem in the windows psql client ? +> > +> > [OK, I'm bringing this back on-list, and bringing it to +> > QingQing's attention, who I secretly hope is the right person +> > to be looking at this problem :)] +> > +> > Just to recap Marc and I have been looking at the performance +> > disparity between windows and linux for a single transaction +> > statement by statement insert on a very narrow table with no +> > keys from a remote client. Marc's observations showed (and I +> > verified) that windows is much slower in this case than it +> > should be. I gprof'ed both the psql client and the server +> > during the insert and didn't see anything seriously out of +> > order...unfortunately QQ's latest win32 performance tweaks +> > haven't helped. +> > +> > Marc's observation that by switching to a linux client drops +> > time down drastically is really intersing! +> +> Could this be a case of the network being slow, as we've seen a couple +> of times before? And if you run psql on the local box, you get it +> double. +> +> Do you get a speed difference between the local windows box and a remote +> wnidows box? +> +> //Magnus +The Windows-Windows test is local (via loopback interface) +The Linux (client) - Windows (server) is via network (100Mbits) + +I can't test with 2 windows box ... I haven't got that much (all machines=20 +linux, except the test one...) + +From pgsql-performance-owner@postgresql.org Wed Nov 2 11:11:31 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id EA9F1D6887 + for ; + Wed, 2 Nov 2005 11:11:30 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 85676-03 + for ; + Wed, 2 Nov 2005 15:11:27 +0000 (GMT) +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 8B512D6899 + for ; + Wed, 2 Nov 2005 11:11:29 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA2FBYtN005647; + Wed, 2 Nov 2005 10:11:34 -0500 (EST) +To: "Magnus Hagander" +Cc: "Merlin Moncure" , + "Marc Cousin" , pgsql-performance@postgresql.org, + "Qingqing Zhou" +Subject: Re: insert performance for win32 +In-reply-to: <6BCB9D8A16AC4241919521715F4D8BCE6C7B4A@algol.sollentuna.se> +References: <6BCB9D8A16AC4241919521715F4D8BCE6C7B4A@algol.sollentuna.se> +Comments: In-reply-to "Magnus Hagander" + message dated "Wed, 02 Nov 2005 14:54:14 +0100" +Date: Wed, 02 Nov 2005 10:11:34 -0500 +Message-ID: <5646.1130944294@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/31 +X-Sequence-Number: 15288 + +"Magnus Hagander" writes: +>> Marc's observation that by switching to a linux client drops +>> time down drastically is really intersing! + +> Could this be a case of the network being slow, + +I'm wondering about nonstandard junk lurking in the TCP stack of the +Windows client machine. Also, I seem to recall something about a "QOS +patch" that people are supposed to apply, or not apply as the case may +be, to get Windows' TCP stack to behave reasonably ... ring a bell? + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Wed Nov 2 11:34:53 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0C665D6800 + for ; + Wed, 2 Nov 2005 11:34:52 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 97352-02 + for ; + Wed, 2 Nov 2005 15:34:46 +0000 (GMT) +Received: from mail.clickdiario.com (mail.clickdiario.com [70.85.167.114]) + by svr1.postgresql.org (Postfix) with ESMTP id 92A95D680E + for ; + Wed, 2 Nov 2005 11:34:48 -0400 (AST) +Received: from localhost (localhost [127.0.0.1]) + by mail.clickdiario.com (Postfix) with ESMTP id B515610009 + for ; + Wed, 2 Nov 2005 09:41:10 -0600 (CST) +Received: from mail.clickdiario.com ([127.0.0.1]) + by localhost (mail.clickdiario.com [127.0.0.1]) (amavisd-new, + port 10024) + with ESMTP id 01342-07 for ; + Wed, 2 Nov 2005 09:41:10 -0600 (CST) +Received: by mail.clickdiario.com (Postfix, from userid 5001) + id 9DECE1000C; Wed, 2 Nov 2005 09:41:10 -0600 (CST) +Received: from cristian1 (unknown [216.230.158.50]) + by mail.clickdiario.com (Postfix) with ESMTP id 01F9510009 + for ; + Wed, 2 Nov 2005 09:41:09 -0600 (CST) +From: "Cristian Prieto" +To: +Subject: Performance difference between sql and pgsql function... +Date: Wed, 2 Nov 2005 09:32:19 -0600 +Message-ID: <007401c5dfc2$9d2c41e0$6500a8c0@gt.ClickDiario.local> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: quoted-printable +X-Mailer: Microsoft Office Outlook 11 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 +Thread-Index: AcXfwpw0gKVGX6nfQS+raXrBjfMWuw== +X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at example.com +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.047 required=5 tests=[AWL=0.047] +X-Spam-Score: 0.047 +X-Spam-Level: +X-Archive-Number: 200511/32 +X-Sequence-Number: 15289 + +There any performance differences between a SQL function written in SQL +language or PL/psSQL language? For example: + +Create or replace function sp_getfreq( + Var1 integer +) returns Boolean as +$$ +Declare + Myval Boolean; +Begin + Select var1 in (select var3 from table1) into myval; + Return myval; +End; +$$ +Language =91plpgsql=92 stable;=A0 + +And with: + +Create or replace function sp_getfreq( + Var1 integer +) returns boolean as +$$ +Select $1 in (select var3 from table1); +$$ +Language =91sql=92 stable; + + +I know the function is really simple, but in theory which of the three = +would +run faster? + + + +From pgsql-performance-owner@postgresql.org Wed Nov 2 12:47:52 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 39B25D787B + for ; + Wed, 2 Nov 2005 12:47:51 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 25047-08 + for ; + Wed, 2 Nov 2005 16:47:50 +0000 (GMT) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id BC373D786C + for ; + Wed, 2 Nov 2005 12:47:49 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: improvise callbacks in plpgsql +Date: Wed, 2 Nov 2005 11:47:48 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD776@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] improvise callbacks in plpgsql +Thread-Index: AcXfOKRHuQpQ7RcvTMmXKhyC8N16PgAkulig +From: "Merlin Moncure" +To: "Jim C. Nasby" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.045 required=5 tests=[AWL=0.045] +X-Spam-Score: 0.045 +X-Spam-Level: +X-Archive-Number: 200511/33 +X-Sequence-Number: 15290 + +> Would you be willing to write up an example of this? We often get +asked +> about support for WITH, so I bet there's other people who would be +very +> interested in what you've got. +>=20 +You can see my blog on the subject here: +http://www.postgresql.org/docs/8.0/interactive/plpgsql.html#PLPGSQL-ADVA +NTAGES + + +It doesn't touch the callback issue. I'm going to hit that at a later +date, a review would be helpful! + +Merlin + +From pgsql-performance-owner@postgresql.org Wed Nov 2 13:04:42 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 71D51D8E9E + for ; + Wed, 2 Nov 2005 13:04:39 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 31169-08 + for ; + Wed, 2 Nov 2005 17:04:37 +0000 (GMT) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 35070D8DAE + for ; + Wed, 2 Nov 2005 13:04:36 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: improvise callbacks in plpgsql +Date: Wed, 2 Nov 2005 12:04:35 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD777@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] improvise callbacks in plpgsql +Thread-Index: AcXfOKRHuQpQ7RcvTMmXKhyC8N16PgAkuligAAD4joA= +From: "Merlin Moncure" +To: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.045 required=5 tests=[AWL=0.045] +X-Spam-Score: 0.045 +X-Spam-Level: +X-Archive-Number: 200511/34 +X-Sequence-Number: 15291 + +oops. my blog is here: :-) +http://people.planetpostgresql.org/merlin/ + +> +http://www.postgresql.org/docs/8.0/interactive/plpgsql.html#PLPGSQL-ADVA +> NTAGES + +From pgsql-performance-owner@postgresql.org Wed Nov 2 13:26:42 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6B3B9D8AD1 + for ; + Wed, 2 Nov 2005 13:26:39 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 41856-02 + for ; + Wed, 2 Nov 2005 17:26:37 +0000 (GMT) +Received: from stark.xeocode.com (stark.xeocode.com [216.58.44.227]) + by svr1.postgresql.org (Postfix) with ESMTP id C56F9D86AD + for ; + Wed, 2 Nov 2005 13:26:37 -0400 (AST) +Received: from localhost ([127.0.0.1] helo=stark.xeocode.com) + by stark.xeocode.com with smtp (Exim 3.36 #1 (Debian)) + id 1EXMNV-0003Xi-00; Wed, 02 Nov 2005 12:26:25 -0500 +To: "Merlin Moncure" +Cc: "Scott Marlowe" , + +Subject: Re: 8.x index insert performance +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD732@Herge.rcsinc.local> +In-Reply-To: <6EE64EF3AB31D5448D0007DD34EEB3417DD732@Herge.rcsinc.local> +From: Greg Stark +Organization: The Emacs Conspiracy; member since 1992 +Date: 02 Nov 2005 12:26:25 -0500 +Message-ID: <87oe53hsfy.fsf@stark.xeocode.com> +Lines: 21 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.01 required=5 tests=[AWL=0.010] +X-Spam-Score: 0.01 +X-Spam-Level: +X-Archive-Number: 200511/35 +X-Sequence-Number: 15292 + +"Merlin Moncure" writes: + +> > select * from sometable where somefield IS NULL won't work because IS +> is +> > not a nomally indexible operator. +> +> Ah, I didn't know that. So there is no real reason not to exclude null +> values from all your indexes :). Reading Tom's recent comments +> everything is clear now. + +There are other reasons. If you want a query like + + SELECT * FROM tab ORDER BY col LIMIT 10 + +to use an index on col then it can't exclude NULLs or else it wouldn't be +useful. (Oracle actually has this problem, you frequently have to add WHERE +col IS NOT NULL" in order to let it use an index.) + + +-- +greg + + +From pgsql-performance-owner@postgresql.org Wed Nov 2 19:34:18 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 93CB9DA21A + for ; + Wed, 2 Nov 2005 19:34:16 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 75312-06 + for ; + Wed, 2 Nov 2005 23:34:13 +0000 (GMT) +Received: from nz.telogis.com (unknown [203.98.10.169]) + by svr1.postgresql.org (Postfix) with ESMTP id E1A4CD9FA3 + for ; + Wed, 2 Nov 2005 19:34:14 -0400 (AST) +Received: from [192.168.3.1] ([192.168.3.1]) + by nz.telogis.com with esmtp; Thu, 03 Nov 2005 12:34:16 +1300 + id 006D3D4E.43694CF8.00007D64 +Message-ID: <43694CF6.4050605@telogis.com> +Date: Thu, 03 Nov 2005 12:34:14 +1300 +From: Ralph Mason +User-Agent: Thunderbird 1.4 (Windows/20050908) +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Trigger Rowsets +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/36 +X-Sequence-Number: 15293 + +I want to do statement level triggers for performance, but it seems +there is no 'updated', 'inserted', or 'deleted' tables inside the +trigger and nothing I can find in the documentation that offers similar +functionality. + +Is there any way that I can access only those rows that were changed? + +Thanks +Ralph + + +From pgsql-www-owner@postgresql.org Wed Nov 2 19:44:31 2005 +X-Original-To: pgsql-www-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 54AA4DA1E2 + for ; + Wed, 2 Nov 2005 19:44:29 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 71783-01 + for ; + Wed, 2 Nov 2005 23:44:26 +0000 (GMT) +Received: from flake.decibel.org (flake.decibel.org [67.100.216.10]) + by svr1.postgresql.org (Postfix) with ESMTP id 0B223D9DBD + for ; Wed, 2 Nov 2005 19:44:28 -0400 (AST) +Received: by flake.decibel.org (Postfix, from userid 1001) + id 8BD811529A; Wed, 2 Nov 2005 17:44:30 -0600 (CST) +Date: Wed, 2 Nov 2005 17:44:30 -0600 +From: "Jim C. Nasby" +To: Merlin Moncure +Cc: pgsql-www@postgresql.org +Subject: Re: [PERFORM] improvise callbacks in plpgsql +Message-ID: <20051102234430.GA55520@pervasive.com> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD76D@Herge.rcsinc.local> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <6EE64EF3AB31D5448D0007DD34EEB3417DD76D@Herge.rcsinc.local> +X-Operating-System: FreeBSD 4.11-RELEASE-p10 i386 +X-Distributed: Join the Effort! http://www.distributed.net +User-Agent: Mutt/1.5.9i +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.008 required=5 tests=[AWL=0.008] +X-Spam-Score: 0.008 +X-Spam-Level: +X-Archive-Number: 200511/12 +X-Sequence-Number: 8727 + +Can we get a link to this posted somewhere? I guess on techdocs? + +On Wed, Nov 02, 2005 at 08:45:02AM -0500, Merlin Moncure wrote: +> > Would you be willing to write up an example of this? We often get +> asked +> > about support for WITH, so I bet there's other people who would be +> very +> > interested in what you've got. +> +> Sure. In fact, I had already decided this to be the next topic on my +> blog. I'm assuming you are asking about tools to deal with recursive +> sets in postgresql. A plpgsql solution is extremely fast, tight, and +> easy if you do it right...Tom's latest suggestions (I have to flesh this +> out some more) provide the missing piece puzzle to make it really tight +> from a classic programming perspective. I don't miss the recursive +> query syntax at all...IMO it's pretty much a hack anyways (to SQL). +> +> Merlin +> +> +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 3: Have you checked our extensive FAQ? +> +> http://www.postgresql.org/docs/faq +> + +-- +Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com +Pervasive Software http://pervasive.com work: 512-231-6117 +vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 + +From pgsql-performance-owner@postgresql.org Wed Nov 2 19:50:14 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 50DDDD9DA1 + for ; + Wed, 2 Nov 2005 19:50:10 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 24017-06 + for ; + Wed, 2 Nov 2005 23:50:07 +0000 (GMT) +Received: from flake.decibel.org (flake.decibel.org [67.100.216.10]) + by svr1.postgresql.org (Postfix) with ESMTP id DBDA4D9DE4 + for ; + Wed, 2 Nov 2005 19:50:08 -0400 (AST) +Received: by flake.decibel.org (Postfix, from userid 1001) + id 36F721525E; Wed, 2 Nov 2005 17:50:12 -0600 (CST) +Date: Wed, 2 Nov 2005 17:50:12 -0600 +From: "Jim C. Nasby" +To: Ralph Mason +Cc: pgsql-performance@postgresql.org +Subject: Re: Trigger Rowsets +Message-ID: <20051102235012.GB55520@pervasive.com> +References: <43694CF6.4050605@telogis.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <43694CF6.4050605@telogis.com> +X-Operating-System: FreeBSD 4.11-RELEASE-p10 i386 +X-Distributed: Join the Effort! http://www.distributed.net +User-Agent: Mutt/1.5.9i +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.008 required=5 tests=[AWL=0.008] +X-Spam-Score: 0.008 +X-Spam-Level: +X-Archive-Number: 200511/37 +X-Sequence-Number: 15294 + +On Thu, Nov 03, 2005 at 12:34:14PM +1300, Ralph Mason wrote: +> I want to do statement level triggers for performance, but it seems +> there is no 'updated', 'inserted', or 'deleted' tables inside the +> trigger and nothing I can find in the documentation that offers similar +> functionality. +> +> Is there any way that I can access only those rows that were changed? + +No. The only way you can do this is with row-level triggers. There's +also not currently any plans to allow statement-level triggers to +interact with the data that was modified by the statement. +-- +Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com +Pervasive Software http://pervasive.com work: 512-231-6117 +vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 + +From pgsql-www-owner@postgresql.org Wed Nov 2 22:52:36 2005 +X-Original-To: pgsql-www-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id E6A48DA463 + for ; + Wed, 2 Nov 2005 22:52:34 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 43889-04 + for ; + Thu, 3 Nov 2005 02:52:30 +0000 (GMT) +Received: from fetter.org (dsl092-188-065.sfo1.dsl.speakeasy.net + [66.92.188.65]) + by svr1.postgresql.org (Postfix) with ESMTP id 0B556D99BC + for ; Wed, 2 Nov 2005 22:52:31 -0400 (AST) +Received: from fetter.org (localhost.localdomain [127.0.0.1]) + by fetter.org (8.13.4/8.12.10) with ESMTP id jA32qYA4001972; + Wed, 2 Nov 2005 18:52:34 -0800 +Received: (from shackle@localhost) + by fetter.org (8.13.4/8.13.4/Submit) id jA32qYYL001971; + Wed, 2 Nov 2005 18:52:34 -0800 +Date: Wed, 2 Nov 2005 18:52:33 -0800 +From: David Fetter +To: "Jim C. Nasby" +Cc: Merlin Moncure , + pgsql-www@postgresql.org +Subject: Re: [PERFORM] improvise callbacks in plpgsql +Message-ID: <20051103025233.GG29465@fetter.org> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD76D@Herge.rcsinc.local> + <20051102234430.GA55520@pervasive.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <20051102234430.GA55520@pervasive.com> +User-Agent: Mutt/1.4.2.1i +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.05 required=5 tests=[AWL=0.050] +X-Spam-Score: 0.05 +X-Spam-Level: +X-Archive-Number: 200511/14 +X-Sequence-Number: 8729 + +On Wed, Nov 02, 2005 at 05:44:30PM -0600, Jim C. Nasby wrote: +> Can we get a link to this posted somewhere? I guess on techdocs? +> +> On Wed, Nov 02, 2005 at 08:45:02AM -0500, Merlin Moncure wrote: +> > > Would you be willing to write up an example of this? We often get +> > asked +> > > about support for WITH, so I bet there's other people who would be +> > very +> > > interested in what you've got. +> > +> > Sure. In fact, I had already decided this to be the next topic on +> > my blog. I'm assuming you are asking about tools to deal with +> > recursive sets in postgresql. A plpgsql solution is extremely +> > fast, tight, and easy if you do it right...Tom's latest +> > suggestions (I have to flesh this out some more) provide the +> > missing piece puzzle to make it really tight from a classic +> > programming perspective. I don't miss the recursive query syntax +> > at all...IMO it's pretty much a hack anyways (to SQL). + +This might be worth putting in the docs somewhere. Tutorial? + +Cheers, +D +-- +David Fetter david@fetter.org http://fetter.org/ +phone: +1 510 893 6100 mobile: +1 415 235 3778 + +Remember to vote! + +From pgsql-performance-owner@postgresql.org Thu Nov 3 01:13:34 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B6985D707D + for ; + Thu, 3 Nov 2005 01:13:31 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 88051-09 + for ; + Thu, 3 Nov 2005 05:13:28 +0000 (GMT) +Received: from calvin.slamb.org (calvin.slamb.org [216.136.66.56]) + by svr1.postgresql.org (Postfix) with ESMTP id AAC3FD7073 + for ; + Thu, 3 Nov 2005 01:13:28 -0400 (AST) +Received: from [192.168.1.52] (adsl-69-230-8-158.dsl.pltn13.pacbell.net + [69.230.8.158]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) + (No client certificate requested) + by calvin.slamb.org (Postfix) with ESMTP + id B6E1A6FD36; Wed, 2 Nov 2005 23:13:27 -0600 (CST) +Mime-Version: 1.0 (Apple Message framework v734) +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: <518C814C-9F9E-42CA-9E8E-C48FAE3B9AFE@slamb.org> +Cc: Dustin Sallings +Content-Transfer-Encoding: 7bit +From: Scott Lamb +Subject: Sorted union +Date: Wed, 2 Nov 2005 21:13:11 -0800 +To: pgsql-performance@postgresql.org +X-Mailer: Apple Mail (2.734) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/38 +X-Sequence-Number: 15295 + +Using PostgreSQL 8.0.4. + +I've got a table with 4.5 million rows that I expect to become huge +(hundred million? who knows). Each row has a start and end time. I +want to retrieve all the events during a timespan in one list; +typical timespans will involve up to a couple rows. If the start and +stop happen at the same time (which is possible), the start must come +first in my sequence. So essentially, I want this: + + select when_stopped as when_happened, + 1 as order_hint + from transaction t + where '2005-10-25 15:00:00' <= when_stopped + and when_stopped <= '2005-10-26 10:00:00' + union all + select when_stopped as when_happened, + 2 as order_hint + from transaction t + where '2005-10-25 15:00:00' <= when_stopped + and when_stopped <= '2005-10-26 10:00:00' + order by when_happened, order_hint; + +I'd really like the first row to be retrieved in O(1) time and the +last in O(n) time (n = number of rows in the timespan, not the whole +table). I previously was doing things manually with flat files. But +there's a sort in PostgreSQL's plan, so I think I'm getting O(n log +n) time for both. It's frustrating to start using a real database and +get performance regressions. + + + QUERY PLAN +------------------------------------------------------------------------ +------------------------------------------------------------------------ +--------------------------------- +Sort (cost=667469.90..676207.19 rows=3494916 width=8) (actual +time=28503.612..31377.254 rows=3364006 loops=1) + Sort Key: when_happened, order_hint + -> Append (cost=0.00..194524.95 rows=3494916 width=8) (actual +time=0.191..14659.712 rows=3364006 loops=1) + -> Subquery Scan "*SELECT* 1" (cost=0.00..97262.48 +rows=1747458 width=8) (actual time=0.190..5375.925 rows=1682003 loops=1) + -> Index Scan using transaction_stopped on +"transaction" t (cost=0.00..79787.90 rows=1747458 width=8) (actual +time=0.186..2962.585 rows=1682003 loops=1) + Index Cond: (('2005-10-25 15:00:00'::timestamp +without time zone <= when_stopped) AND (when_stopped <= '2005-10-26 +10:00:00'::timestamp without time zone)) + -> Subquery Scan "*SELECT* 2" (cost=0.00..97262.48 +rows=1747458 width=8) (actual time=0.167..5449.151 rows=1682003 loops=1) + -> Index Scan using transaction_stopped on +"transaction" t (cost=0.00..79787.90 rows=1747458 width=8) (actual +time=0.163..3026.730 rows=1682003 loops=1) + Index Cond: (('2005-10-25 15:00:00'::timestamp +without time zone <= when_stopped) AND (when_stopped <= '2005-10-26 +10:00:00'::timestamp without time zone)) +Total runtime: 33312.814 ms +(10 rows) + +Each side of the union is retrieved in sorted order, but it doesn't +seem to realize that. There seem to be two things it's missing: + +(1) It doesn't recognize that constant expressions are irrelevant to +the sort. I.e., the first half of the union: + + select when_started as when_happened, + 1 as order_hint + from transaction t + where '2005-10-25 15:00:00' <= when_started + and when_started <= '2005-10-26 10:00:00' + order by when_happened, order_hint; + +does this: + + + QUERY PLAN +------------------------------------------------------------------------ +------------------------------------------------------------------------ +--------------------- +Sort (cost=291770.42..296139.05 rows=1747453 width=8) (actual +time=8462.026..9895.715 rows=1681994 loops=1) + Sort Key: when_started, 1 + -> Index Scan using transaction_started on "transaction" t +(cost=0.00..79788.21 rows=1747453 width=8) (actual +time=0.190..2953.393 rows=1681994 loops=1) + Index Cond: (('2005-10-25 15:00:00'::timestamp without time +zone <= when_started) AND (when_started <= '2005-10-26 +10:00:00'::timestamp without time zone)) +Total runtime: 10835.114 ms +(5 rows) + +The sort is unnecessary. If I take out the constant order_hint, it +works: + + select when_started as when_happened + from transaction t + where '2005-10-25 15:00:00' <= when_started + and when_started <= '2005-10-26 10:00:00' + order by when_happened; + + + QUERY PLAN +------------------------------------------------------------------------ +------------------------------------------------------------------------ +--------------- +Index Scan using transaction_started on "transaction" t +(cost=0.00..79788.21 rows=1747453 width=8) (actual +time=0.189..2715.513 rows=1681994 loops=1) + Index Cond: (('2005-10-25 15:00:00'::timestamp without time zone +<= when_started) AND (when_started <= '2005-10-26 +10:00:00'::timestamp without time zone)) +Total runtime: 3630.817 ms +(3 rows) + +(2) It doesn't recognize that each half of the union is sorted and +thus they only need to be merged. This is true even without the +order_hint bits: + + select when_stopped as when_happened + from transaction t + where '2005-10-25 15:00:00' <= when_stopped + and when_stopped <= '2005-10-26 10:00:00' + union all + select when_stopped as when_happened + from transaction t + where '2005-10-25 15:00:00' <= when_stopped + and when_stopped <= '2005-10-26 10:00:00' + order by when_happened; + + + QUERY PLAN +------------------------------------------------------------------------ +------------------------------------------------------------------------ +--------------------------------- +Sort (cost=667469.90..676207.19 rows=3494916 width=8) (actual +time=28088.783..30898.854 rows=3364006 loops=1) + Sort Key: when_happened + -> Append (cost=0.00..194524.95 rows=3494916 width=8) (actual +time=0.153..14410.485 rows=3364006 loops=1) + -> Subquery Scan "*SELECT* 1" (cost=0.00..97262.48 +rows=1747458 width=8) (actual time=0.152..5287.092 rows=1682003 loops=1) + -> Index Scan using transaction_stopped on +"transaction" t (cost=0.00..79787.90 rows=1747458 width=8) (actual +time=0.149..2885.905 rows=1682003 loops=1) + Index Cond: (('2005-10-25 15:00:00'::timestamp +without time zone <= when_stopped) AND (when_stopped <= '2005-10-26 +10:00:00'::timestamp without time zone)) + -> Subquery Scan "*SELECT* 2" (cost=0.00..97262.48 +rows=1747458 width=8) (actual time=0.152..5254.425 rows=1682003 loops=1) + -> Index Scan using transaction_stopped on +"transaction" t (cost=0.00..79787.90 rows=1747458 width=8) (actual +time=0.149..2905.861 rows=1682003 loops=1) + Index Cond: (('2005-10-25 15:00:00'::timestamp +without time zone <= when_stopped) AND (when_stopped <= '2005-10-26 +10:00:00'::timestamp without time zone)) +Total runtime: 32766.566 ms +(10 rows) + +Is there some way I can work around this? The best I can think of now +is to open two connections, one for each half of the union. I can do +the merge manually on the client side. It'd work, but I'd really +prefer the database server take care of this for me. + +-- +Scott Lamb + + +From pgsql-performance-owner@postgresql.org Thu Nov 3 01:27:28 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0B184D6E2C + for ; + Thu, 3 Nov 2005 01:27:28 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 03107-03 + for ; + Thu, 3 Nov 2005 05:27:26 +0000 (GMT) +Received: from calvin.slamb.org (calvin.slamb.org [216.136.66.56]) + by svr1.postgresql.org (Postfix) with ESMTP id CBDE8D6D78 + for ; + Thu, 3 Nov 2005 01:27:26 -0400 (AST) +Received: from [192.168.1.52] (adsl-69-230-8-158.dsl.pltn13.pacbell.net + [69.230.8.158]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) + (No client certificate requested) + by calvin.slamb.org (Postfix) with ESMTP + id 03C7E6FD36; Wed, 2 Nov 2005 23:27:26 -0600 (CST) +In-Reply-To: <518C814C-9F9E-42CA-9E8E-C48FAE3B9AFE@slamb.org> +References: <518C814C-9F9E-42CA-9E8E-C48FAE3B9AFE@slamb.org> +Mime-Version: 1.0 (Apple Message framework v734) +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: +Cc: pgsql-performance@postgresql.org, + Dustin Sallings +Content-Transfer-Encoding: 7bit +From: Scott Lamb +Subject: Re: Sorted union +Date: Wed, 2 Nov 2005 21:27:02 -0800 +To: Scott Lamb +X-Mailer: Apple Mail (2.734) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/39 +X-Sequence-Number: 15296 + +On 2 Nov 2005, at 21:13, Scott Lamb wrote: + +> I want to retrieve all the events during a timespan in one list; +> typical timespans will involve up to a couple rows. + +Err, I meant up to a couple million rows. With two rows, I wouldn't +be so concerned about performance. ;) + +-- +Scott Lamb + + +From pgsql-performance-owner@postgresql.org Thu Nov 3 03:11:47 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8BCF7D7115 + for ; + Thu, 3 Nov 2005 03:11:46 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 36890-07 + for ; + Thu, 3 Nov 2005 07:11:44 +0000 (GMT) +Received: from cliff.cs.toronto.edu (cliff.cs.toronto.edu [128.100.3.120]) + by svr1.postgresql.org (Postfix) with ESMTP id 237E2D7101 + for ; + Thu, 3 Nov 2005 03:11:44 -0400 (AST) +Received: from eon.cs (eon.cs.toronto.edu [128.100.3.15]) + by cliff.cs.toronto.edu (Postfix) with ESMTP id 197A85FD0C; + Thu, 3 Nov 2005 02:11:43 -0500 (EST) +Received: by eon.cs (Postfix, from userid 1300) + id 281EF7E9; Thu, 3 Nov 2005 02:11:43 -0500 (EST) +Received: from localhost (localhost [127.0.0.1]) by eon.cs (Postfix) with + ESMTP + id 1AE3F544; Thu, 3 Nov 2005 02:11:43 -0500 (EST) +Date: Thu, 3 Nov 2005 02:11:43 -0500 (EST) +From: Qingqing Zhou +X-X-Sender: zhouqq@eon.cs +To: Merlin Moncure +Cc: Marc Cousin , pgsql-performance@postgresql.org +Subject: Re: insert performance for win32 +In-Reply-To: <6EE64EF3AB31D5448D0007DD34EEB3417DD76C@Herge.rcsinc.local> +Message-ID: +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD76C@Herge.rcsinc.local> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.363 required=5 tests=[AWL=-0.116, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.363 +X-Spam-Level: +X-Archive-Number: 200511/40 +X-Sequence-Number: 15297 + + + +On Wed, 2 Nov 2005, Merlin Moncure wrote: + +> > +> > By the way, we've tried to insert into the windows database from a +> > linux psql client, via the network. In this configuration, inserting +> > is only about 2 times slower than inserting locally (the linux client +> > had a slower CPU 1700Mhz agains 3000). Could it be related to a +> > problem in the windows psql client ? +> > + +If you put client/server on the same machine, then we don't know how the +CPU is splitted. Can you take a look at the approximate number by +observing the task manager data while running? + +If communication code is the suspect, can we measure the difference if we +disable the redefinition of recv()/send() etc in port/win32.h (may require +change related code a little bit as well). In this way, the socket will +not be able to pickup signals, but let see if there is any performance +difference first. + +Regards, +Qingqing + + +> +> [OK, I'm bringing this back on-list, and bringing it to QingQing's +> attention, who I secretly hope is the right person to be looking at this +> problem :)] +> +P.s. You scared me ;-) + +From pgsql-performance-owner@postgresql.org Thu Nov 3 09:53:02 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 1BDC3D845E + for ; + Thu, 3 Nov 2005 09:53:00 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 75425-07 + for ; + Thu, 3 Nov 2005 13:52:56 +0000 (GMT) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id B48B1D841B + for ; + Thu, 3 Nov 2005 09:52:58 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Sorted union +Date: Thu, 3 Nov 2005 08:53:00 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD78D@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Sorted union +Thread-Index: AcXgNckSE0inABpgStGapacgBYykRwARnoPA +From: "Merlin Moncure" +To: "Scott Lamb" +Cc: , + "Dustin Sallings" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.044 required=5 tests=[AWL=0.044] +X-Spam-Score: 0.044 +X-Spam-Level: +X-Archive-Number: 200511/41 +X-Sequence-Number: 15298 + +> select when_stopped as when_happened, +> 1 as order_hint +> from transaction t +> where '2005-10-25 15:00:00' <=3D when_stopped +> and when_stopped <=3D '2005-10-26 10:00:00' +> union all +> select when_stopped as when_happened, +> 2 as order_hint +> from transaction t +> where '2005-10-25 15:00:00' <=3D when_stopped +> and when_stopped <=3D '2005-10-26 10:00:00' +> order by when_happened, order_hint; + +hmm, try pushing the union into a subquery...this is better style +because it's kind of ambiguous if the ordering will apply before/after +the union. + +select q.when from +( + select 1 as hint, start_time as when [...] + union all + select 2 as hint, end_time as when [...] +) q order by q.seq, when + +question: why do you want to flatten the table...is it not easier to +work with as records? + +Merlin +=20 + +From pgsql-www-owner@postgresql.org Thu Nov 3 10:01:51 2005 +X-Original-To: pgsql-www-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 80AB7D82A3 + for ; + Thu, 3 Nov 2005 10:01:50 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 84259-05 + for ; + Thu, 3 Nov 2005 14:01:46 +0000 (GMT) +Received: from xproxy.gmail.com (xproxy.gmail.com [66.249.82.206]) + by svr1.postgresql.org (Postfix) with ESMTP id EEEC4D8346 + for ; Thu, 3 Nov 2005 10:01:47 -0400 (AST) +Received: by xproxy.gmail.com with SMTP id i30so533870wxd + for ; Thu, 03 Nov 2005 06:01:52 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=f/m7y5veOcTkNDhx9/W1pyhTgqWrbzBhPERdBmIFnPgEVI08jBiq85Yx+HXjG/4cHLAKkIsD37+otHg309C9SF2Zzz8uv9by6mZ/JFxTDG08Bsr76qt627Y0SikWnREFQpSzolPgEbx3asMSs/WnuE+OPmHHjxXdXppfFXt/Ni8= +Received: by 10.70.27.8 with SMTP id a8mr673217wxa; + Thu, 03 Nov 2005 06:01:52 -0800 (PST) +Received: by 10.70.53.14 with HTTP; Thu, 3 Nov 2005 06:01:52 -0800 (PST) +Message-ID: +Date: Thu, 3 Nov 2005 09:01:52 -0500 +From: Merlin Moncure +To: David Fetter +Subject: Re: [PERFORM] improvise callbacks in plpgsql +Cc: pgsql-www@postgresql.org, jnasby@pervasive.com +In-Reply-To: <20051103025233.GG29465@fetter.org> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD76D@Herge.rcsinc.local> + <20051102234430.GA55520@pervasive.com> + <20051103025233.GG29465@fetter.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.332 required=5 tests=[RCVD_IN_BL_SPAMCOP_NET=1.332] +X-Spam-Score: 1.332 +X-Spam-Level: * +X-Archive-Number: 200511/18 +X-Sequence-Number: 8733 + +On 11/2/05, David Fetter wrote: +> On Wed, Nov 02, 2005 at 05:44:30PM -0600, Jim C. Nasby wrote: +> > Can we get a link to this posted somewhere? I guess on techdocs? +> > +> > On Wed, Nov 02, 2005 at 08:45:02AM -0500, Merlin Moncure wrote: +> > > > Would you be willing to write up an example of this? We often get +> > > asked +> > > > about support for WITH, so I bet there's other people who would be +> > > very +> > > > interested in what you've got. +> > > +> > > Sure. In fact, I had already decided this to be the next topic on +> > > my blog. I'm assuming you are asking about tools to deal with +> > > recursive sets in postgresql. A plpgsql solution is extremely +> > > fast, tight, and easy if you do it right...Tom's latest +> > > suggestions (I have to flesh this out some more) provide the +> > > missing piece puzzle to make it really tight from a classic +> > > programming perspective. I don't miss the recursive query syntax +> > > at all...IMO it's pretty much a hack anyways (to SQL). +> +> This might be worth putting in the docs somewhere. Tutorial? + +you guys can do anything you like with it... + +I'm working on part two which will build on the previous example and +show how to pass in a function to use as a callback, kind of like a +functor. + +btw, the blog examples are a reduction of my own personal code which +went through a vast simplification process. I need to test it a bt +before it hits doc quality, there might be some errors lurking there. + +Merlin + +From pgsql-performance-owner@postgresql.org Thu Nov 3 11:14:14 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 47E5AD8377 + for ; + Thu, 3 Nov 2005 11:14:13 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 30060-08 + for ; + Thu, 3 Nov 2005 15:14:09 +0000 (GMT) +Received: from smtp-gw-cl-d.dmv.com (smtp-gw-cl-d.dmv.com [216.240.97.42]) + by svr1.postgresql.org (Postfix) with ESMTP id 9E5EED8258 + for ; + Thu, 3 Nov 2005 11:14:11 -0400 (AST) +Received: from mail-gw-cl-a.dmv.com (mail-gw-cl-a.dmv.com [216.240.97.38]) + by smtp-gw-cl-d.dmv.com (8.12.10/8.12.10) with ESMTP id jA3FEEf5090973 + for ; + Thu, 3 Nov 2005 10:14:14 -0500 (EST) (envelope-from sven@dmv.com) +Received: from lanshark.dmv.com (lanshark.dmv.com [216.240.97.46]) + by mail-gw-cl-a.dmv.com (8.12.9/8.12.9) with ESMTP id jA3FEDLR008362 + for ; + Thu, 3 Nov 2005 10:14:13 -0500 (EST) (envelope-from sven@dmv.com) +Subject: Function with table%ROWTYPE globbing +From: Sven Willenberger +To: pgsql-performance@postgresql.org +Content-Type: text/plain +Date: Thu, 03 Nov 2005 10:14:15 -0500 +Message-Id: <1131030856.9769.3.camel@lanshark.dmv.com> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.1.1 +Content-Transfer-Encoding: 7bit +X-Scanned-By: MIMEDefang 2.48 on 216.240.97.42 +X-Scanned-By: MIMEDefang 2.48 on 216.240.97.38 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.527 required=5 tests=[AWL=-0.352, + DNS_FROM_RFC_WHOIS=0.879] +X-Spam-Score: 0.527 +X-Spam-Level: +X-Archive-Number: 200511/42 +X-Sequence-Number: 15299 + +Postgresql 8.0.4 using plpgsql + +The basic function is set up as: +CREATE FUNCTION add_data(t_row mytable) RETURNS VOID AS $func$ +DECLARE + newtable text; + thesql text; +BEGIN + INSERT INTO newtable thename from mytable where lookup.id = +t_row.id; + thesql := 'INSERT INTO ' || newtable || VALUES (' || t_row.* ')'; + EXECUTE thesql; + RETURN; +END; +$func$ LANGUAGE plpgsql VOLATILE; + +SELECT add_data(t.*) FROM mytable t where .... +ERROR: column "*" not found in data type mytable + +Now I have tried to drop the * but then there is no concatenation +function to join text to a table%ROWTYPE. So my question is how can I +make this dynamic insert statement without listing out every +t_row.colname? Or, alternatively, is there a better way to parse out +each row of a table into subtables based on a column value? + +Sven + + + +From pgsql-performance-owner@postgresql.org Thu Nov 3 11:37:30 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A867FD8346 + for ; + Thu, 3 Nov 2005 11:37:28 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 42695-02 + for ; + Thu, 3 Nov 2005 15:37:23 +0000 (GMT) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id B5370D8262 + for ; + Thu, 3 Nov 2005 11:37:25 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Function with table%ROWTYPE globbing +Date: Thu, 3 Nov 2005 10:37:16 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD796@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Function with table%ROWTYPE globbing +Thread-Index: AcXgicGkAisXRLFaQtWgOQWbOoTTTAAAVALQ +From: "Merlin Moncure" +To: "Sven Willenberger" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.387 required=5 tests=[AWL=-0.300, + UNRESOLVED_TEMPLATE=0.687] +X-Spam-Score: 0.387 +X-Spam-Level: +X-Archive-Number: 200511/43 +X-Sequence-Number: 15300 + +> Postgresql 8.0.4 using plpgsql +>=20 +> The basic function is set up as: +> CREATE FUNCTION add_data(t_row mytable) RETURNS VOID AS $func$ +> DECLARE +> newtable text; +> thesql text; +> BEGIN +> INSERT INTO newtable thename from mytable where lookup.id =3D +> t_row.id; +> thesql :=3D 'INSERT INTO ' || newtable || VALUES (' || t_row.* = +')'; +> EXECUTE thesql; +> RETURN; +> END; +> $func$ LANGUAGE plpgsql VOLATILE; +>=20 +> SELECT add_data(t.*) FROM mytable t where .... +> ERROR: column "*" not found in data type mytable +>=20 +> Now I have tried to drop the * but then there is no concatenation +> function to join text to a table%ROWTYPE. So my question is how can I +> make this dynamic insert statement without listing out every +> t_row.colname? Or, alternatively, is there a better way to parse out +> each row of a table into subtables based on a column value? + +I don't think it's possible. Rowtypes, etc are not first class yet (on +to do). What I would do is pass the table name, where clause, etc into +the add_data function and rewrite as insert...select and do the whole +thing in one operation. + +Merlin + +From pgsql-performance-owner@postgresql.org Thu Nov 3 11:41:23 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 38A91D7AAE + for ; + Thu, 3 Nov 2005 11:41:20 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 43945-01 + for ; + Thu, 3 Nov 2005 15:41:16 +0000 (GMT) +Received: from calvin.slamb.org (calvin.slamb.org [216.136.66.56]) + by svr1.postgresql.org (Postfix) with ESMTP id 933E9D76A1 + for ; + Thu, 3 Nov 2005 11:41:18 -0400 (AST) +Received: from [192.168.1.52] (adsl-69-230-8-158.dsl.pltn13.pacbell.net + [69.230.8.158]) (using TLSv1 with cipher RC4-MD5 (128/128 bits)) + (No client certificate requested) + by calvin.slamb.org (Postfix) with ESMTP + id 1A5B06FCFE; Thu, 3 Nov 2005 09:41:20 -0600 (CST) +Message-ID: <436A2F9A.4050202@slamb.org> +Date: Thu, 03 Nov 2005 07:41:14 -0800 +From: Scott Lamb +User-Agent: Thunderbird 1.4.1 (Macintosh/20051006) +MIME-Version: 1.0 +To: Merlin Moncure +Cc: pgsql-performance@postgresql.org, + Dustin Sallings +Subject: Re: Sorted union +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD78D@Herge.rcsinc.local> +In-Reply-To: <6EE64EF3AB31D5448D0007DD34EEB3417DD78D@Herge.rcsinc.local> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/44 +X-Sequence-Number: 15301 + +Merlin Moncure wrote: +> hmm, try pushing the union into a subquery...this is better style +> because it's kind of ambiguous if the ordering will apply before/after +> the union. + +Seems to be a little slower. There's a new "subquery scan" step. + + explain analyze + select q.when_happened from ( + select when_stopped as when_happened, + 1 as order_hint + from transaction t + where '2005-10-25 15:00:00' <= when_stopped + and when_stopped <= '2005-10-26 10:00:00' + union all + select when_stopped as when_happened, + 2 as order_hint + from transaction t + where '2005-10-25 15:00:00' <= when_stopped + and when_stopped <= '2005-10-26 10:00:00' + ) q order by when_happened, order_hint; + + + QUERY PLAN + +--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- + Sort (cost=713013.96..721751.25 rows=3494916 width=12) (actual +time=34392.264..37237.148 rows=3364006 loops=1) + Sort Key: when_happened, order_hint + -> Subquery Scan q (cost=0.00..229474.11 rows=3494916 width=12) +(actual time=0.194..20283.452 rows=3364006 loops=1) + -> Append (cost=0.00..194524.95 rows=3494916 width=8) +(actual time=0.191..14967.632 rows=3364006 loops=1) + -> Subquery Scan "*SELECT* 1" (cost=0.00..97262.48 +rows=1747458 width=8) (actual time=0.189..5535.139 rows=1682003 loops=1) + -> Index Scan using transaction_stopped on +"transaction" t (cost=0.00..79787.90 rows=1747458 width=8) (actual +time=0.186..3097.268 rows=1682003 loops=1) + Index Cond: (('2005-10-25 +15:00:00'::timestamp without time zone <= when_stopped) AND +(when_stopped <= '2005-10-26 10:00:00'::timestamp without time zone)) + -> Subquery Scan "*SELECT* 2" (cost=0.00..97262.48 +rows=1747458 width=8) (actual time=0.173..5625.155 rows=1682003 loops=1) + -> Index Scan using transaction_stopped on +"transaction" t (cost=0.00..79787.90 rows=1747458 width=8) (actual +time=0.169..3146.714 rows=1682003 loops=1) + Index Cond: (('2005-10-25 +15:00:00'::timestamp without time zone <= when_stopped) AND +(when_stopped <= '2005-10-26 10:00:00'::timestamp without time zone)) + Total runtime: 39775.225 ms +(11 rows) + +> question: why do you want to flatten the table...is it not easier to +> work with as records? + +For most things, yes. But I'm making a bunch of different graphs from +these data, and a few of them are much easier with events. The best +example is my concurrency graph. Whenever there's a start event, it goes +up one. Whenever there's a stop event, it goes down one. It's completely +trivial once you have it separated into events. + +Thanks, +Scott + +From pgsql-performance-owner@postgresql.org Thu Nov 3 12:21:01 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 01F1AD89D3 + for ; + Thu, 3 Nov 2005 12:20:59 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 57059-07 + for ; + Thu, 3 Nov 2005 16:20:57 +0000 (GMT) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 6D503D88B0 + for ; + Thu, 3 Nov 2005 12:20:57 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Sorted union +Date: Thu, 3 Nov 2005 11:20:55 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD798@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Sorted union +Thread-Index: AcXgjQt1GiGuThvDT+G6bdCWHJcKOgAAYaOw +From: "Merlin Moncure" +To: "Scott Lamb" +Cc: , + "Dustin Sallings" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.047 required=5 tests=[AWL=0.047] +X-Spam-Score: 0.047 +X-Spam-Level: +X-Archive-Number: 200511/45 +X-Sequence-Number: 15302 + + +> Merlin Moncure wrote: +> > hmm, try pushing the union into a subquery...this is better style +> > because it's kind of ambiguous if the ordering will apply +before/after +> > the union. +>=20 +> Seems to be a little slower. There's a new "subquery scan" step. + +I figured. However it's more correct, I'm not sure if the original +query is necessarily guaranteed to give the right answer (in terms of +ordering). It might though. + +>=20 +> > question: why do you want to flatten the table...is it not easier to +> > work with as records? +>=20 +> For most things, yes. But I'm making a bunch of different graphs from +> these data, and a few of them are much easier with events. The best +> example is my concurrency graph. Whenever there's a start event, it +goes +> up one. Whenever there's a stop event, it goes down one. It's +completely +> trivial once you have it separated into events. + +well, if you don't mind attempting things that are not trivial, how +about trying:=20 + +select t, (select count(*) from transaction where t between happened +and when_stopped) from +( + select ((generate_series(1,60) * scale)::text::interval) + '12:00 +pm'::time as t +) q; +for example, to check concurrency at every second for a minute (starting +from 1 second) after 12:00 pm, (scale is zero in this case), + +select t, (select count(*) from transaction where t between happened +and when_stopped) from +( + select (generate_series(1,60)::text::interval) + '12:00 pm'::time as +t +) q; + +this could be a win depending on how much data you pull into your +concurrency graph. maybe not though. =20 + +Merlin + +From pgsql-performance-owner@postgresql.org Thu Nov 3 14:10:12 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 97F60D98F6 + for ; + Thu, 3 Nov 2005 14:08:07 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14142-02 + for ; + Thu, 3 Nov 2005 18:07:54 +0000 (GMT) +Received: from calvin.slamb.org (calvin.slamb.org [216.136.66.56]) + by svr1.postgresql.org (Postfix) with ESMTP id 34EBCD8C93 + for ; + Thu, 3 Nov 2005 14:02:55 -0400 (AST) +Received: by calvin.slamb.org (Postfix, from userid 103) + id A62A26FCFE; Thu, 3 Nov 2005 12:02:55 -0600 (CST) +Received: from [? @IPv6:::1] (localhost.slamb.org [127.0.0.1]) + by calvin.slamb.org (Postfix) with ESMTP + id 574CB6FCE5; Thu, 3 Nov 2005 12:02:48 -0600 (CST) +In-Reply-To: <6EE64EF3AB31D5448D0007DD34EEB3417DD798@Herge.rcsinc.local> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD798@Herge.rcsinc.local> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: <9757F82C-51CC-4185-B364-FC23C267D976@slamb.org> +Cc: , + "Dustin Sallings" +Content-Transfer-Encoding: 7bit +From: Scott Lamb +Subject: Re: Sorted union +Date: Thu, 3 Nov 2005 10:02:47 -0800 +To: "Merlin Moncure" +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/47 +X-Sequence-Number: 15304 + +On Nov 3, 2005, at 8:20 AM, Merlin Moncure wrote: +> select t, (select count(*) from transaction where t between happened +> and when_stopped) from +> ( +> select ((generate_series(1,60) * scale)::text::interval) + '12:00 +> pm'::time as t +> ) q; + +Wow. I hadn't known about generate_series, but there are a bunch of +places I've needed it. + +As cool as this is, though, I don't think it helps me. There's +another event-driven graph that I need. For lack of a better name, I +call it the slot graph. Every single transaction is graphed as a +horizontal line from its start time to its end time, with a vertical +line at the start and stop. Successful, timed out, and failed +transactions are green, black, and red, respectively. I use it in a +couple different ways: + +(1) on short timescales, it's nice to look at individual +transactions. My tester will max out at either a rate or a +concurrency. If I'm having problems, I'll get bursts of timeouts. +This graph is the one that makes it clear why - it shows how things +align, etc. Actually, even for longer timespans, this is still +helpful - it's nice to see that most of the slots are filled with +timing-out transactions when the rate falls. + +(2) It can show you if something affects all of the transactions at +once. When we did a database failover test, we saw a bunch of +failures (as expected; our application isn't responsible for +retries). This graph is the one that showed us that _all_ +transactions that were active at a specific time failed and that no +other transactions failed. (There was a sharp vertical line of reds +and blacks in the larger block of greens). + +I wish I could just show these to you, rather than describing them. +It's all proprietary data, though. Maybe soon I'll have similar +graphs of my open source SSL proxy. + +But the point is, I don't think I can represent this information +without sending every data point to my application. I assign slots by +the start time and free them by the stop time. + +But I think there is something I can do: I can just do a query of the +transaction table sorted by start time. My graph tool can keep a +priority queue of all active transactions, keyed by the stop time. +Whenever it grabs a new event, it can peek at the next start time but +check if there are any stop times before it. Then at the end, it can +pick up the rest of the stop times. The concurrency will never exceed +a few thousand, so the additional CPU time and memory complexity are +not a problem. As a bonus, I will no longer need my index on the stop +time. Dropping it will save a lot of disk space. + +Thanks for getting me off the "I need a fast query that returns these +exact results" mindset. It is good to step back and look at the big +picture. + +Mind you, I still think PostgreSQL should be able to perform that +sorted union fast. Maybe sometime I'll have enough free time to take +my first plunge into looking at a database query planner. + +Regards, +Scott + +-- +Scott Lamb + + + +From pgsql-performance-owner@postgresql.org Thu Nov 3 14:10:12 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 93869DB74D + for ; + Thu, 3 Nov 2005 14:08:25 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 12679-09 + for ; + Thu, 3 Nov 2005 18:08:18 +0000 (GMT) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id D19DDDB9B3 + for ; + Thu, 3 Nov 2005 14:03:23 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: insert performance for win32 +Date: Thu, 3 Nov 2005 13:03:19 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD79B@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +Thread-Index: AcXgRdh+7ruBaqXcTaSB7/1u8tIkXgAWRwEw +From: "Merlin Moncure" +To: "Qingqing Zhou" +Cc: , + "Marc Cousin" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.046 required=5 tests=[AWL=0.046] +X-Spam-Score: 0.046 +X-Spam-Level: +X-Archive-Number: 200511/46 +X-Sequence-Number: 15303 + +> On Wed, 2 Nov 2005, Merlin Moncure wrote: +> If you put client/server on the same machine, then we don't know how +the +> CPU is splitted. Can you take a look at the approximate number by +> observing the task manager data while running? + +ok, I generated a test case which was 250k inserts to simple two column +table all in single transaction. Every 50k inserts, time is recorded +via timeofday(). =20 + +Running from remote, Time progression is: +First 50k: 20 sec +Second : 29 sec +[...] +final: : 66 sec + +so, clear upward progression of time/rec. Initial time is 2.5k +inserts/sec which is decent but not great for such a narrow table. CPU +time on server starts around 50% and drops in exact proportion to insert +performance. My earlier gprof test also suggest there is no smoking gun +sucking down all the cpu time. + +cpu time on the client is very volatile but with a clear increase over +time starting around 20 and ending perhaps 60. My client box is pretty +quick, 3ghz p4. + +Running the script locally, from the server, cpu time is pegged at 100% +and stays...first 50k is 23 sec with a much worse decomposition to +almost three minutes for final 50k. + +Merlin + + + +=20 +> If communication code is the suspect, can we measure the difference if +we +> disable the redefinition of recv()/send() etc in port/win32.h (may +require +> change related code a little bit as well). In this way, the socket +will +> not be able to pickup signals, but let see if there is any performance +> difference first. +>=20 +> Regards, +> Qingqing +>=20 +>=20 +> > +> > [OK, I'm bringing this back on-list, and bringing it to QingQing's +> > attention, who I secretly hope is the right person to be looking at +this +> > problem :)] +> > +> P.s. You scared me ;-) + +From pgsql-performance-owner@postgresql.org Thu Nov 3 14:23:30 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 4209ED88B0 + for ; + Thu, 3 Nov 2005 14:21:10 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 20132-05 + for ; + Thu, 3 Nov 2005 18:21:07 +0000 (GMT) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 8CBA6DB774 + for ; + Thu, 3 Nov 2005 14:21:07 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Sorted union +Date: Thu, 3 Nov 2005 13:21:07 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD79E@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Sorted union +Thread-Index: AcXgoNGK2Q0NbIHfQli0xbEvVRrdpQAAQEZg +From: "Merlin Moncure" +To: "Scott Lamb" +Cc: , + "Dustin Sallings" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.046 required=5 tests=[AWL=0.046] +X-Spam-Score: 0.046 +X-Spam-Level: +X-Archive-Number: 200511/48 +X-Sequence-Number: 15305 + +> Wow. I hadn't known about generate_series, but there are a bunch of +> places I've needed it. + +It's a wonder tool :). +=20 +> But I think there is something I can do: I can just do a query of the +> transaction table sorted by start time. My graph tool can keep a + +Reading the previous paragraphs I was just about to suggest this. This +is a much more elegant method...you are reaping the benefits of having +normalized your working set. You were trying to denormalize it back to +what you were used to. Yes, now you can drop your index and simplify +your queries...normalized data is always more 'natural'. + +> Mind you, I still think PostgreSQL should be able to perform that +> sorted union fast. Maybe sometime I'll have enough free time to take +> my first plunge into looking at a database query planner. + +I'm not so sure I agree, by using union you were basically pulling two +independent sets (even if they were from the same table) that needed to +be ordered. There is zero chance of using the index here for ordering +because you are ordering a different set than the one being indexed. +Had I not been able to talk you out of de-normalizing your table I was +going to suggest rigging up a materialized view and indexing that: + +http://jonathangardner.net/PostgreSQL/materialized_views/matviews.html + +Merlin + +From pgsql-performance-owner@postgresql.org Thu Nov 3 14:33:23 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CE42ED9126 + for ; + Thu, 3 Nov 2005 14:32:53 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 25208-03 + for ; + Thu, 3 Nov 2005 18:32:50 +0000 (GMT) +Received: from gwmta.wicourts.gov (gwmta.wicourts.gov [165.219.244.99]) + by svr1.postgresql.org (Postfix) with ESMTP id 52E92D86B3 + for ; + Thu, 3 Nov 2005 14:32:49 -0400 (AST) +Received: from Courts-MTA by gwmta.wicourts.gov + with Novell_GroupWise; Thu, 03 Nov 2005 12:32:46 -0600 +Message-Id: <436A03660200002500000452@gwmta.wicourts.gov> +X-Mailer: Novell GroupWise Internet Agent 7.0 +Date: Thu, 03 Nov 2005 12:32:06 -0600 +From: "Kevin Grittner" +To: , +Cc: , +Subject: Re: Sorted union +Mime-Version: 1.0 +Content-Type: text/plain; charset=US-ASCII +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.002 required=5 tests=[AWL=0.002] +X-Spam-Score: 0.002 +X-Spam-Level: +X-Archive-Number: 200511/49 +X-Sequence-Number: 15306 + +The ANSI/ISO specs are not at all ambiguous on this. An +ORDER BY is not allowed for the SELECT statements within +a UNION. It must come at the end and applied to the resulting +UNION. + +Similarly, the column names in the result come from the first +query in the UNION. Column names in the query on the right +side of a UNION are immaterial. + +Unless we have reason to believe that PostgreSQL is +non-compliant on this point, I don't think it is a good idea to +slow the query down with the subquery. + +-Kevin + + +>>> "Merlin Moncure" >>> + +> Merlin Moncure wrote: +> > hmm, try pushing the union into a subquery...this is better style +> > because it's kind of ambiguous if the ordering will apply +before/after +> > the union. +> +> Seems to be a little slower. There's a new "subquery scan" step. + +I figured. However it's more correct, I'm not sure if the original +query is necessarily guaranteed to give the right answer (in terms of +ordering). It might though. + + +From pgsql-performance-owner@postgresql.org Thu Nov 3 14:41:06 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 934D4DB9FC + for ; + Thu, 3 Nov 2005 14:40:28 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 29436-06 + for ; + Thu, 3 Nov 2005 18:40:17 +0000 (GMT) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 891A2DB3B4 + for ; + Thu, 3 Nov 2005 14:37:52 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Sorted union +Date: Thu, 3 Nov 2005 13:37:52 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD7A0@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Sorted union +Thread-Index: AcXgpP6w83f1o3uVTrGZ5otYMfJ8gwAAJ7Uw +From: "Merlin Moncure" +To: "Kevin Grittner" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.045 required=5 tests=[AWL=0.045, UPPERCASE_25_50=0] +X-Spam-Score: 0.045 +X-Spam-Level: +X-Archive-Number: 200511/50 +X-Sequence-Number: 15307 + +> The ANSI/ISO specs are not at all ambiguous on this. An +> ORDER BY is not allowed for the SELECT statements within +> a UNION. It must come at the end and applied to the resulting +> UNION. + +Interesting :/=20 + +Merlin + +From pgsql-performance-owner@postgresql.org Thu Nov 3 14:49:21 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id EE6E1DBD3B + for ; + Thu, 3 Nov 2005 14:49:00 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 34377-06 + for ; + Thu, 3 Nov 2005 18:48:56 +0000 (GMT) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id C485FDBB07 + for ; + Thu, 3 Nov 2005 14:42:09 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: insert performance for win32 +Date: Thu, 3 Nov 2005 13:42:08 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD7A1@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +Thread-Index: AcXgRdh+7ruBaqXcTaSB7/1u8tIkXgAWRwEwAAGzVFA= +From: "Merlin Moncure" +To: "Qingqing Zhou" +Cc: , "Magnus Hagander" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.045 required=5 tests=[AWL=0.045] +X-Spam-Score: 0.045 +X-Spam-Level: +X-Archive-Number: 200511/51 +X-Sequence-Number: 15308 + +Both win32 send/recv have pgwin32_poll_signals() in them. This is +glorified WaitForSingleObjectEx on global pgwin32_signal_event. This is +probably part of the problem. Can we work some of the same magic you +put into check interrupts macro? + +ISTM everything also in win32 functions is either API call, or marginal +case. + +Merlin + +From pgsql-performance-owner@postgresql.org Thu Nov 3 14:55:06 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 00DD6DA9F3 + for ; + Thu, 3 Nov 2005 14:52:53 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 36638-05 + for ; + Thu, 3 Nov 2005 18:52:45 +0000 (GMT) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 4568BDB7E8 + for ; + Thu, 3 Nov 2005 14:47:09 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: insert performance for win32 +Date: Thu, 3 Nov 2005 13:47:09 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD7A3@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +Thread-Index: AcXgRdh+7ruBaqXcTaSB7/1u8tIkXgAWRwEwAAGzVFAAAEez8A== +From: "Merlin Moncure" +To: "Qingqing Zhou" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.045 required=5 tests=[AWL=0.045] +X-Spam-Score: 0.045 +X-Spam-Level: +X-Archive-Number: 200511/52 +X-Sequence-Number: 15309 + +> Both win32 send/recv have pgwin32_poll_signals() in them. This is +> glorified WaitForSingleObjectEx on global pgwin32_signal_event. This +is +> probably part of the problem. Can we work some of the same magic you +put +> into check interrupts macro? + +Whoop! following a cvs update I see this is already nailed :) Back to +the drawing board... + +Merlin + +From pgsql-performance-owner@postgresql.org Thu Nov 3 15:11:52 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B7E77DB971 + for ; + Thu, 3 Nov 2005 15:11:50 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 47070-01 + for ; + Thu, 3 Nov 2005 19:11:45 +0000 (GMT) +X-Greylist: delayed 00:20:35.173706 by SQLgrey- +Received: from calvin.slamb.org (calvin.slamb.org [216.136.66.56]) + by svr1.postgresql.org (Postfix) with ESMTP id 821E2DB972 + for ; + Thu, 3 Nov 2005 15:10:28 -0400 (AST) +Received: by calvin.slamb.org (Postfix, from userid 103) + id 8B08E6FD1E; Thu, 3 Nov 2005 12:49:53 -0600 (CST) +Received: from [??@IPv6:::1] (localhost.slamb.org [127.0.0.1]) + by calvin.slamb.org (Postfix) with ESMTP + id 7DA096FD03; Thu, 3 Nov 2005 12:49:51 -0600 (CST) +In-Reply-To: <6EE64EF3AB31D5448D0007DD34EEB3417DD79E@Herge.rcsinc.local> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD79E@Herge.rcsinc.local> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: +Cc: , + "Dustin Sallings" +Content-Transfer-Encoding: 7bit +From: Scott Lamb +Subject: Re: Sorted union +Date: Thu, 3 Nov 2005 10:49:50 -0800 +To: "Merlin Moncure" +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/53 +X-Sequence-Number: 15310 + +On Nov 3, 2005, at 10:21 AM, Merlin Moncure wrote: +> Reading the previous paragraphs I was just about to suggest this. +> This +> is a much more elegant method...you are reaping the benefits of having +> normalized your working set. You were trying to denormalize it +> back to +> what you were used to. Yes, now you can drop your index and simplify +> your queries...normalized data is always more 'natural'. + +I'm not sure normalized is the right word. In either case, I'm +storing it in the same form. In either case, my ConcurrencyProcessor +class gets the same form. The only difference is if the database +splits the rows or if my application does so. + +But we're essentially agreed. This is the algorithm I'm going to try +implementing, and I think it will work out well. It also means +sending about half as much data from the database to the application. + +>> Mind you, I still think PostgreSQL should be able to perform that +>> sorted union fast. Maybe sometime I'll have enough free time to take +>> my first plunge into looking at a database query planner. +> +> I'm not so sure I agree, by using union you were basically pulling two +> independent sets (even if they were from the same table) that +> needed to +> be ordered. + +Yes. + +> There is zero chance of using the index here for ordering +> because you are ordering a different set than the one being indexed. + +I don't think that's true. It just needs to look at the idea of +independently ordering each element of the union and then merging +that, compared to the cost of grabbing the union and then ordering +it. In this case, the former cost is about 0 - it already has +independently ordered them, and the merge algorithm is trivial. + + +Regards, +Scott + +-- +Scott Lamb + + + +From pgsql-performance-owner@postgresql.org Thu Nov 3 15:22:53 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6BDEED8E9B + for ; + Thu, 3 Nov 2005 15:22:47 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 47108-08 + for ; + Thu, 3 Nov 2005 19:22:44 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mx-2.sollentuna.net (mx-2.sollentuna.net [195.84.163.199]) + by svr1.postgresql.org (Postfix) with ESMTP id D93E9D86A1 + for ; + Thu, 3 Nov 2005 15:22:44 -0400 (AST) +Received: from ALGOL.sollentuna.se (janus.sollentuna.se [62.65.68.67]) + by mx-2.sollentuna.net (Postfix) with ESMTP + id 3080C8F297; Thu, 3 Nov 2005 20:04:01 +0100 (CET) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Subject: Re: insert performance for win32 +Date: Thu, 3 Nov 2005 20:04:01 +0100 +Message-ID: <6BCB9D8A16AC4241919521715F4D8BCE92E7E6@algol.sollentuna.se> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +thread-index: AcXgRdh+7ruBaqXcTaSB7/1u8tIkXgAWRwEwAAGzVFAAAN8NUA== +From: "Magnus Hagander" +To: "Merlin Moncure" , + "Qingqing Zhou" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.034 required=5 tests=[AWL=0.034] +X-Spam-Score: 0.034 +X-Spam-Level: +X-Archive-Number: 200511/54 +X-Sequence-Number: 15311 + +> Both win32 send/recv have pgwin32_poll_signals() in them. =20 +> This is glorified WaitForSingleObjectEx on global=20 +> pgwin32_signal_event. This is probably part of the problem. =20 +> Can we work some of the same magic you put into check=20 +> interrupts macro? +>=20 +> ISTM everything also in win32 functions is either API call,=20 +> or marginal case. + +Uh, we already do that, don't we? +http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/port/win32/ +socket.c?rev=3D1.10 +has: + +static int +pgwin32_poll_signals(void) +{ + if (UNBLOCKED_SIGNAL_QUEUE()) + { + pgwin32_dispatch_queued_signals(); + errno =3D EINTR; + return 1; + } + return 0; +} + + + +Are you testing this on 8.0.x? Or a pre-RC version of 8.1? + +//Magnus + +From pgsql-performance-owner@postgresql.org Thu Nov 3 15:32:48 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 7B5F7D7B0F + for ; + Thu, 3 Nov 2005 15:32:47 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 49058-09 + for ; + Thu, 3 Nov 2005 19:32:45 +0000 (GMT) +X-Greylist: delayed 00:20:07.389174 by SQLgrey- +Received: from gwmta.wicourts.gov (gwmta.wicourts.gov [165.219.244.99]) + by svr1.postgresql.org (Postfix) with ESMTP id 04800D70AE + for ; + Thu, 3 Nov 2005 15:32:45 -0400 (AST) +Received: from Courts-MTA by gwmta.wicourts.gov + with Novell_GroupWise; Thu, 03 Nov 2005 13:12:39 -0600 +Message-Id: <436A0C8F0200002500000459@gwmta.wicourts.gov> +X-Mailer: Novell GroupWise Internet Agent 7.0 +Date: Thu, 03 Nov 2005 13:11:43 -0600 +From: "Kevin Grittner" +To: , +Cc: , +Subject: Re: Sorted union +Mime-Version: 1.0 +Content-Type: text/plain; charset=US-ASCII +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.002 required=5 tests=[AWL=0.002] +X-Spam-Score: 0.002 +X-Spam-Level: +X-Archive-Number: 200511/55 +X-Sequence-Number: 15312 + +Just as an FYI, if you want to reassure yourself that the ORDER BY +is being applied as intended, you could do the following: + +( + select 1 as hint, start_time as when [...] + union all + select 2 as hint, end_time as when [...] +) order by seq, when + +This is ANSI/ISO standard, and works in PostgreSQL (based on +a quick test). + + +>>> "Merlin Moncure" >>> + +hmm, try pushing the union into a subquery...this is better style +because it's kind of ambiguous if the ordering will apply before/after +the union. + +select q.when from +( + select 1 as hint, start_time as when [...] + union all + select 2 as hint, end_time as when [...] +) q order by q.seq, when + + +From pgsql-performance-owner@postgresql.org Thu Nov 3 22:32:15 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 82A77D9532 + for ; + Thu, 3 Nov 2005 22:32:00 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 95731-07 + for ; + Fri, 4 Nov 2005 02:31:55 +0000 (GMT) +X-Greylist: delayed 03:03:17.816287 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 14CBAD909E + for ; + Thu, 3 Nov 2005 22:31:48 -0400 (AST) +Received: from cliff.cs.toronto.edu (cliff.cs.toronto.edu [128.100.3.120]) + by svr2.postgresql.org (Postfix) with ESMTP id ACD87F0CE7 + for ; + Thu, 3 Nov 2005 20:25:51 +0000 (GMT) +Received: from josh.db (josh.db.toronto.edu [128.100.3.95]) + by cliff.cs.toronto.edu (Postfix) with ESMTP id 8EA955FD0B; + Thu, 3 Nov 2005 15:25:42 -0500 (EST) +Received: by josh.db (Postfix, from userid 1300) + id 863C93140B; Thu, 3 Nov 2005 15:25:42 -0500 (EST) +Received: from localhost (localhost [127.0.0.1]) + by josh.db (Postfix) with ESMTP + id 83FB0313EE; Thu, 3 Nov 2005 15:25:42 -0500 (EST) +Date: Thu, 3 Nov 2005 15:25:42 -0500 (EST) +From: Qingqing Zhou +X-X-Sender: zhouqq@josh.db +To: Magnus Hagander +Cc: Merlin Moncure , + pgsql-performance@postgresql.org +Subject: Re: insert performance for win32 +In-Reply-To: <6BCB9D8A16AC4241919521715F4D8BCE92E7E6@algol.sollentuna.se> +Message-ID: +References: <6BCB9D8A16AC4241919521715F4D8BCE92E7E6@algol.sollentuna.se> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.362 required=5 tests=[AWL=-0.117, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.362 +X-Spam-Level: +X-Archive-Number: 200511/64 +X-Sequence-Number: 15321 + + + +On Thu, 3 Nov 2005, Magnus Hagander wrote: + +> > Both win32 send/recv have pgwin32_poll_signals() in them. +> > This is glorified WaitForSingleObjectEx on global +> > pgwin32_signal_event. This is probably part of the problem. +> > Can we work some of the same magic you put into check +> > interrupts macro? +> > +> +> Uh, we already do that, don't we? +> http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/port/win32/ +> socket.c?rev=1.10 +> has: +> + +Yeah, we did this. I am thinking of just use simple mechanism of the win32 +sockets, which could not pick up signals, but I would like to see if there +is any difference -- do you think there is any point to try this? + +Regards, +Qingqing + +From pgsql-performance-owner@postgresql.org Thu Nov 3 16:30:33 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5B3B3D7ED7 + for ; + Thu, 3 Nov 2005 16:30:32 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 68164-10 + for ; + Thu, 3 Nov 2005 20:30:28 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mx-2.sollentuna.net (mx-2.sollentuna.net [195.84.163.199]) + by svr1.postgresql.org (Postfix) with ESMTP id 8093CD7215 + for ; + Thu, 3 Nov 2005 16:30:29 -0400 (AST) +Received: from ALGOL.sollentuna.se (janus.sollentuna.se [62.65.68.67]) + by mx-2.sollentuna.net (Postfix) with ESMTP + id A2AEB8F293; Thu, 3 Nov 2005 21:30:30 +0100 (CET) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Subject: Re: insert performance for win32 +Date: Thu, 3 Nov 2005 21:30:30 +0100 +Message-ID: <6BCB9D8A16AC4241919521715F4D8BCE92E7EF@algol.sollentuna.se> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +thread-index: AcXgtMX4n/JL8oHyQlWDhrJfF1FpVAAAJfqg +From: "Magnus Hagander" +To: "Qingqing Zhou" +Cc: "Merlin Moncure" , + +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.034 required=5 tests=[AWL=0.034] +X-Spam-Score: 0.034 +X-Spam-Level: +X-Archive-Number: 200511/56 +X-Sequence-Number: 15313 + +> > > Both win32 send/recv have pgwin32_poll_signals() in them. +> > > This is glorified WaitForSingleObjectEx on global=20 +> > > pgwin32_signal_event. This is probably part of the problem. +> > > Can we work some of the same magic you put into check interrupts=20 +> > > macro? +> > > +> > +> > Uh, we already do that, don't we? +> >=20 +> http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/port/win3 +> > 2/ +> > socket.c?rev=3D1.10 +> > has: +> > +>=20 +> Yeah, we did this. I am thinking of just use simple mechanism=20 +> of the win32 sockets, which could not pick up signals, but I=20 +> would like to see if there is any difference -- do you think=20 +> there is any point to try this? + +Sorry, I don't follow you here - what do you mean to do? Remove the +event completely so we can't wait on it? + +//Magnus + +From pgsql-performance-owner@postgresql.org Thu Nov 3 16:34:57 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9841FD7115 + for ; + Thu, 3 Nov 2005 16:34:55 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 72483-04 + for ; + Thu, 3 Nov 2005 20:34:53 +0000 (GMT) +X-Greylist: delayed 00:09:10.095397 by SQLgrey- +Received: from cliff.cs.toronto.edu (cliff.cs.toronto.edu [128.100.3.120]) + by svr1.postgresql.org (Postfix) with ESMTP id 39454D683B + for ; + Thu, 3 Nov 2005 16:34:53 -0400 (AST) +Received: from josh.db (josh.db.toronto.edu [128.100.3.95]) + by cliff.cs.toronto.edu (Postfix) with ESMTP id 693F95FD0B; + Thu, 3 Nov 2005 15:34:55 -0500 (EST) +Received: by josh.db (Postfix, from userid 1300) + id 57B873140B; Thu, 3 Nov 2005 15:34:55 -0500 (EST) +Received: from localhost (localhost [127.0.0.1]) + by josh.db (Postfix) with ESMTP + id 55B1B313EE; Thu, 3 Nov 2005 15:34:55 -0500 (EST) +Date: Thu, 3 Nov 2005 15:34:55 -0500 (EST) +From: Qingqing Zhou +X-X-Sender: zhouqq@josh.db +To: Magnus Hagander +Cc: Merlin Moncure , + pgsql-performance@postgresql.org +Subject: Re: insert performance for win32 +In-Reply-To: <6BCB9D8A16AC4241919521715F4D8BCE92E7EF@algol.sollentuna.se> +Message-ID: +References: <6BCB9D8A16AC4241919521715F4D8BCE92E7EF@algol.sollentuna.se> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.363 required=5 tests=[AWL=-0.116, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.363 +X-Spam-Level: +X-Archive-Number: 200511/57 +X-Sequence-Number: 15314 + + + +On Thu, 3 Nov 2005, Magnus Hagander wrote: + +> +> Sorry, I don't follow you here - what do you mean to do? Remove the +> event completely so we can't wait on it? +> + +I'd like to use the win32 provided recv(), send() functions instead of +redirect them to pgwin32_recv()/pgwin32_send(), just like libpq does. If +we do this, we will lose some functionalities, but I'd like to see the +performance difference first. -- do you think that will be any difference? + +Regards, +Qingqing + +From pgsql-performance-owner@postgresql.org Thu Nov 3 16:39:28 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5DC2FD7115 + for ; + Thu, 3 Nov 2005 16:39:27 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 73245-05 + for ; + Thu, 3 Nov 2005 20:39:25 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mx-2.sollentuna.net (mx-2.sollentuna.net [195.84.163.199]) + by svr1.postgresql.org (Postfix) with ESMTP id 0F5E6D683B + for ; + Thu, 3 Nov 2005 16:39:26 -0400 (AST) +Received: from ALGOL.sollentuna.se (janus.sollentuna.se [62.65.68.67]) + by mx-2.sollentuna.net (Postfix) with ESMTP + id 7AEEE8F293; Thu, 3 Nov 2005 21:39:27 +0100 (CET) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Subject: Re: insert performance for win32 +Date: Thu, 3 Nov 2005 21:39:27 +0100 +Message-ID: <6BCB9D8A16AC4241919521715F4D8BCE92E7F1@algol.sollentuna.se> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +thread-index: AcXgtg3rq7rzIltjRWC3Mk46UpIA0gAAGC+A +From: "Magnus Hagander" +To: "Qingqing Zhou" +Cc: "Merlin Moncure" , + +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.034 required=5 tests=[AWL=0.034] +X-Spam-Score: 0.034 +X-Spam-Level: +X-Archive-Number: 200511/58 +X-Sequence-Number: 15315 + +> > Sorry, I don't follow you here - what do you mean to do? Remove the=20 +> > event completely so we can't wait on it? +> > +>=20 +> I'd like to use the win32 provided recv(), send() functions=20 +> instead of redirect them to pgwin32_recv()/pgwin32_send(),=20 +> just like libpq does. If we do this, we will lose some=20 +> functionalities, but I'd like to see the performance=20 +> difference first. -- do you think that will be any difference? + +Doesn't work, really. It will no longer be possible to send a signal to +an idle backend. The idle backend will be blocking on recv(), that's how +it works. So unless we can get around that somehow, it's a non-starter I +think. + +I doubt there will be much performance difference, as you hav eto hit +the kernel anyway (in the recv/send call). But that part is just a guess +:-) + + +//Magnus + +From pgsql-performance-owner@postgresql.org Thu Nov 3 23:02:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id C9D50DA676 + for ; + Thu, 3 Nov 2005 23:02:47 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14034-05 + for ; + Fri, 4 Nov 2005 03:02:41 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 23EABD9C63 + for ; + Thu, 3 Nov 2005 23:01:33 -0400 (AST) +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr2.postgresql.org (Postfix) with ESMTP id 3457EF1291 + for ; + Thu, 3 Nov 2005 21:04:45 +0000 (GMT) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: insert performance for win32 +Date: Thu, 3 Nov 2005 16:04:37 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD7B4@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +Thread-Index: AcXgtg1YULAECka0R+OccrN0knwNvgAA0Hsg +From: "Merlin Moncure" +To: "Qingqing Zhou" +Cc: , "Magnus Hagander" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.044 required=5 tests=[AWL=0.044] +X-Spam-Score: 0.044 +X-Spam-Level: +X-Archive-Number: 200511/65 +X-Sequence-Number: 15322 + +> > Sorry, I don't follow you here - what do you mean to do? Remove the +> > event completely so we can't wait on it? +> > +>=20 +> I'd like to use the win32 provided recv(), send() functions instead of +> redirect them to pgwin32_recv()/pgwin32_send(), just like libpq does. +If +> we do this, we will lose some functionalities, but I'd like to see the +> performance difference first. -- do you think that will be any +difference? + +I personally strongly doubt this will make a diffenrence. Anyways I +think we might be looking at the wrong place. Here was my test: +1. drop/create table two fields (id int, f text) no keys +2. begin +3. insert 500k rows. every 50k get time get geometric growth in insert +time +4. commit + +I am doing this via=20 +type dump.sql | psql -q mydb + +I rearrange: +every 50k rows get time but also restart transaction. I would ex + +Guess what...no change. This was a shocker. So I wrap dump.sql with +another file that is just=20 +\i dump.sql +\i dump.sql + +and get time to insert 50k recs resets after first dump... + +Merlin=20 + +From pgsql-performance-owner@postgresql.org Thu Nov 3 17:06:33 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 78A5DD7ED7 + for ; + Thu, 3 Nov 2005 17:06:32 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 77306-09 + for ; + Thu, 3 Nov 2005 21:06:30 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from cliff.cs.toronto.edu (cliff.cs.toronto.edu [128.100.3.120]) + by svr1.postgresql.org (Postfix) with ESMTP id 149E7D7B0F + for ; + Thu, 3 Nov 2005 17:06:31 -0400 (AST) +Received: from eon.cs (eon.cs.toronto.edu [128.100.3.15]) + by cliff.cs.toronto.edu (Postfix) with ESMTP id 078CE5FD0B; + Thu, 3 Nov 2005 16:06:33 -0500 (EST) +Received: by eon.cs (Postfix, from userid 1300) + id 089E6698; Thu, 3 Nov 2005 16:06:32 -0500 (EST) +Received: from localhost (localhost [127.0.0.1]) by eon.cs (Postfix) with + ESMTP + id EFFC6544; Thu, 3 Nov 2005 16:06:32 -0500 (EST) +Date: Thu, 3 Nov 2005 16:06:32 -0500 (EST) +From: Qingqing Zhou +X-X-Sender: zhouqq@eon.cs +To: Magnus Hagander +Cc: Merlin Moncure , + pgsql-performance@postgresql.org +Subject: Re: insert performance for win32 +In-Reply-To: <6BCB9D8A16AC4241919521715F4D8BCE92E7F1@algol.sollentuna.se> +Message-ID: +References: <6BCB9D8A16AC4241919521715F4D8BCE92E7F1@algol.sollentuna.se> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.363 required=5 tests=[AWL=-0.116, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.363 +X-Spam-Level: +X-Archive-Number: 200511/59 +X-Sequence-Number: 15316 + + + +On Thu, 3 Nov 2005, Magnus Hagander wrote: + +> > > Sorry, I don't follow you here - what do you mean to do? Remove the +> > > event completely so we can't wait on it? +> > > +> > +> > I'd like to use the win32 provided recv(), send() functions +> > instead of redirect them to pgwin32_recv()/pgwin32_send(), +> > just like libpq does. If we do this, we will lose some +> > functionalities, but I'd like to see the performance +> > difference first. -- do you think that will be any difference? +> +> Doesn't work, really. It will no longer be possible to send a signal to +> an idle backend. The idle backend will be blocking on recv(), that's how +> it works. So unless we can get around that somehow, it's a non-starter I +> think. + +Yeah, agreed. An alternative is set tiemout like 100 ms or so. When +timeout happens, check the signals. But I guess you will be strongly +against it. + +> +> I doubt there will be much performance difference, as you hav eto hit +> the kernel anyway (in the recv/send call). But that part is just a guess +> :-) + +I know what you mean ... I will take a look -- if the patch (not +including fix signaling problem), if doesn't change much, I will give it a +try. + +Regards, +Qingqing + +From pgsql-performance-owner@postgresql.org Thu Nov 3 17:15:32 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 41198D7226 + for ; + Thu, 3 Nov 2005 17:15:31 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 88384-05 + for ; + Thu, 3 Nov 2005 21:15:29 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mx-2.sollentuna.net (mx-2.sollentuna.net [195.84.163.199]) + by svr1.postgresql.org (Postfix) with ESMTP id 0192ED7215 + for ; + Thu, 3 Nov 2005 17:15:29 -0400 (AST) +Received: from ALGOL.sollentuna.se (janus.sollentuna.se [62.65.68.67]) + by mx-2.sollentuna.net (Postfix) with ESMTP + id E396F8F295; Thu, 3 Nov 2005 22:15:30 +0100 (CET) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Subject: Re: insert performance for win32 +Date: Thu, 3 Nov 2005 22:15:31 +0100 +Message-ID: <6BCB9D8A16AC4241919521715F4D8BCE92E7F5@algol.sollentuna.se> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +thread-index: AcXguni/4FW9/y6GRYurysYRSVvPrwAASnSQ +From: "Magnus Hagander" +To: "Qingqing Zhou" +Cc: "Merlin Moncure" , + +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.033 required=5 tests=[AWL=0.033] +X-Spam-Score: 0.033 +X-Spam-Level: +X-Archive-Number: 200511/60 +X-Sequence-Number: 15317 + +> > > I'd like to use the win32 provided recv(), send()=20 +> functions instead=20 +> > > of redirect them to pgwin32_recv()/pgwin32_send(), just=20 +> like libpq=20 +> > > does. If we do this, we will lose some functionalities,=20 +> but I'd like=20 +> > > to see the performance difference first. -- do you think=20 +> that will=20 +> > > be any difference? +> > +> > Doesn't work, really. It will no longer be possible to send=20 +> a signal=20 +> > to an idle backend. The idle backend will be blocking on recv(),=20 +> > that's how it works. So unless we can get around that=20 +> somehow, it's a=20 +> > non-starter I think. +>=20 +> Yeah, agreed. An alternative is set tiemout like 100 ms or=20 +> so. When timeout happens, check the signals. But I guess you=20 +> will be strongly against it. + +Not on principle, but I don't think it'll give us enough gain for the +cost. But if it does, I'm certainly not against it. + + + +//Magnus + +From pgsql-performance-owner@postgresql.org Thu Nov 3 18:13:47 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8168CD7226 + for ; + Thu, 3 Nov 2005 18:13:46 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 05979-08 + for ; + Thu, 3 Nov 2005 22:13:44 +0000 (GMT) +Received: from news.hub.org (news.hub.org [200.46.204.72]) + by svr1.postgresql.org (Postfix) with ESMTP id 532F5D7215 + for ; + Thu, 3 Nov 2005 18:13:45 -0400 (AST) +Received: from news.hub.org (news.hub.org [200.46.204.72]) + by news.hub.org (8.13.1/8.13.1) with ESMTP id jA3MDh7j009930 + for ; Thu, 3 Nov 2005 22:13:43 GMT + (envelope-from news@news.hub.org) +Received: (from news@localhost) + by news.hub.org (8.13.1/8.13.1/Submit) id jA3LkcMj000589 + for pgsql-performance@postgresql.org; Thu, 3 Nov 2005 21:46:38 GMT + (envelope-from news) +From: "Qingqing Zhou" +X-Newsgroups: pgsql.performance +Subject: Re: insert performance for win32 +Date: Thu, 3 Nov 2005 16:46:52 -0500 +Organization: Hub.Org Networking Services +Lines: 29 +Message-ID: +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD79B@Herge.rcsinc.local> +X-Complaints-To: usenet@news.hub.org +X-Newsreader: Microsoft Outlook Express 6.00.2900.2180 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 +X-RFC2646: Format=Flowed; Original +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=-1.414 required=5 tests=[ALL_TRUSTED=-1.44, + AWL=0.026] +X-Spam-Score: -1.414 +X-Spam-Level: +X-Archive-Number: 200511/61 +X-Sequence-Number: 15318 + + +""Merlin Moncure"" wrote +> +> Running from remote, Time progression is: +> First 50k: 20 sec +> Second : 29 sec +> [...] +> final: : 66 sec +> +This may due to the maintainence cost of a big transaction, I am not sure +... Tom? + +> so, clear upward progression of time/rec. Initial time is 2.5k +> inserts/sec which is decent but not great for such a narrow table. CPU +> time on server starts around 50% and drops in exact proportion to insert +> performance. My earlier gprof test also suggest there is no smoking gun +> sucking down all the cpu time. +> + +Not to 100%, so this means the server is always starving. It is waiting on +something -- of couse not lock. That's why I think there is some problem on +network communication. Another suspect will be the write - I knwo NTFS +system will issue an internal log when extending a file. To remove the +second suspect, I will try to hack the source to do a "fake" write ... + +Regards, +Qingqing + + + +From pgsql-performance-owner@postgresql.org Thu Nov 3 18:41:35 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 877DAD7A5C + for ; + Thu, 3 Nov 2005 18:41:34 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 08747-08 + for ; + Thu, 3 Nov 2005 22:41:29 +0000 (GMT) +X-Greylist: delayed 00:06:20.281051 by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.193]) + by svr1.postgresql.org (Postfix) with ESMTP id C1283D7215 + for ; + Thu, 3 Nov 2005 18:41:30 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id i3so155608wra + for ; + Thu, 03 Nov 2005 14:41:33 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:mime-version:content-type; + b=b0MG3xvC6n+m4eFkw4c44/4aLh47k6NGIy7JcII5nZBs/pGtJaA8jyV0XT+AKJNBSsEoIdPyEv7NDrectsaYU5AD6n9vvdguon5ntb9r3kbzVfa6Ox77mBgrFAmJY4T67Am2bRj6lEDoh/yag9iL+udDKvvZ0iKyQmZLrpvTrn4= +Received: by 10.54.148.4 with SMTP id v4mr1014335wrd; + Thu, 03 Nov 2005 14:35:13 -0800 (PST) +Received: by 10.54.105.8 with HTTP; Thu, 3 Nov 2005 14:35:13 -0800 (PST) +Message-ID: <6c21003b0511031435m3217574fk3013f41a4a265222@mail.gmail.com> +Date: Thu, 3 Nov 2005 16:35:13 -0600 +From: Don Drake +To: pgsql-performance@postgresql.org +Subject: Encoding on 8.0.4 +MIME-Version: 1.0 +Content-Type: multipart/alternative; + boundary="----=_Part_1643_24455213.1131057313075" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.056 required=5 tests=[AWL=0.055, + HTML_MESSAGE=0.001] +X-Spam-Score: 0.056 +X-Spam-Level: +X-Archive-Number: 200511/62 +X-Sequence-Number: 15319 + +------=_Part_1643_24455213.1131057313075 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline + +I recently upgraded my DB from 7.4.3 to 8.0.4 and I've noticed the followin= +g +errors appearing in my serverlog: + + +2005-11-03 05:56:57 CST 127.0.0.1(38858) ERROR: Unicode characters greater +than or equal to 0x10000 are not supported +2005-11-03 06:04:09 CST 127.0.0.1(38954) ERROR: invalid byte sequence for +encoding "UNICODE": 0xe02d76 +2005-11-03 06:04:21 CST 127.0.0.1(38964) ERROR: invalid byte sequence for +encoding "UNICODE": 0xe02d76 +2005-11-03 06:11:35 CST 127.0.0.1(39072) ERROR: Unicode characters greater +than or equal to 0x10000 are not supported +2005-11-03 06:23:23 CST 127.0.0.1(39657) ERROR: invalid byte sequence for +encoding "UNICODE": 0xd40d +2005-11-03 08:10:02 CST 127.0.0.1(44073) ERROR: invalid byte sequence for +encoding "UNICODE": 0xe46973 +2005-11-03 08:21:13 CST 127.0.0.1(44711) ERROR: Unicode characters greater +than or equal to 0x10000 are not supported +2005-11-03 08:26:36 CST 127.0.0.1(44745) ERROR: invalid byte sequence for +encoding "UNICODE": 0xc447 +2005-11-03 08:40:59 CST 127.0.0.1(45087) ERROR: invalid byte sequence for +encoding "UNICODE": 0xdd20 +2005-11-03 09:14:52 CST 127.0.0.1(46009) ERROR: Unicode characters greater +than or equal to 0x10000 are not supported + +I never received these errors on when running 7.4.3. I used the default +encodings on 7.4.3 and I tried chaning client_encoding from sql_ascii to +UNICODE and I'm still seeing this. I'm storing in a text data type email +that contains other characterset characters. + +Any ideas on how to resolve this? + +-Don + +-- +Donald Drake +President +Drake Consulting +http://www.drakeconsult.com/ +http://www.MailLaunder.com/ +http://www.mobilemeridian.com/ +312-560-1574 + +------=_Part_1643_24455213.1131057313075 +Content-Type: text/html; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline + +I recently upgraded my DB from 7.4.3 to 8.0.4 and I've noticed the followin= +g errors appearing in my serverlog:
+ +
+ +
+ +2005-11-03 05:56:57 CST 127.0.0.1(38858) ERROR:  Unicode characters gr= +eater than or equal to 0x10000 are not supported
+ +2005-11-03 06:04:09 CST 127.0.0.1(38954) ERROR:  invalid byte sequence= + for encoding "UNICODE": 0xe02d76
+ +2005-11-03 06:04:21 CST 127.0.0.1(38964) ERROR:  invalid byte sequence= + for encoding "UNICODE": 0xe02d76
+ +2005-11-03 06:11:35 CST 127.0.0.1(39072) ERROR:  Unicode characters gr= +eater than or equal to 0x10000 are not supported
+ +2005-11-03 06:23:23 CST 127.0.0.1(39657) ERROR:  invalid byte sequence= + for encoding "UNICODE": 0xd40d
+ +2005-11-03 08:10:02 CST 127.0.0.1(44073) ERROR:  invalid byte sequence= + for encoding "UNICODE": 0xe46973
+ +2005-11-03 08:21:13 CST 127.0.0.1(44711) ERROR:  Unicode characters gr= +eater than or equal to 0x10000 are not supported
+ +2005-11-03 08:26:36 CST 127.0.0.1(44745) ERROR:  invalid byte sequence= + for encoding "UNICODE": 0xc447
+ +2005-11-03 08:40:59 CST 127.0.0.1(45087) ERROR:  invalid byte sequence= + for encoding "UNICODE": 0xdd20
+ +2005-11-03 09:14:52 CST 127.0.0.1(46009) ERROR:  Unicode characters gr= +eater than or equal to 0x10000 are not supported
+ +
+ +I never received these errors on when running 7.4.3.  I used the +default encodings on 7.4.3 and I tried chaning client_encoding from +sql_ascii to UNICODE and I'm still seeing this. I'm storing in a text +data type email that contains other characterset +characters.  
+ +
+ +Any ideas on how to resolve this?
+ +
+ +-Don

--
Donald Drake
President
Drake Consult= +ing
http://www.drakeconsult.c= +om/ + +
http://www.MailLaunder.com/ +
http://www.mobilemeridia= +n.com/
312-560-1574
+ + + +------=_Part_1643_24455213.1131057313075-- + +From pgsql-performance-owner@postgresql.org Thu Nov 3 19:30:07 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id EDEADD7115 + for ; + Thu, 3 Nov 2005 19:30:05 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 26912-10 + for ; + Thu, 3 Nov 2005 23:30:03 +0000 (GMT) +X-Greylist: delayed 01:43:21.814595 by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 7004FD683B + for ; + Thu, 3 Nov 2005 19:30:04 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id 8B43931058; Fri, 4 Nov 2005 00:30:05 +0100 (MET) +From: "Qingqing Zhou" +X-Newsgroups: pgsql.performance +Subject: Re: insert performance for win32 +Date: Thu, 3 Nov 2005 18:30:12 -0500 +Organization: Hub.Org Networking Services +Lines: 76 +Message-ID: +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD79B@Herge.rcsinc.local> + +X-Complaints-To: usenet@news.hub.org +X-Priority: 3 +X-MSMail-Priority: Normal +X-Newsreader: Microsoft Outlook Express 6.00.2900.2180 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 +X-RFC2646: Format=Flowed; Response +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.566 required=5 tests=[AWL=0.566] +X-Spam-Score: 0.566 +X-Spam-Level: +X-Archive-Number: 200511/63 +X-Sequence-Number: 15320 + + +"Qingqing Zhou" wrote +> +> Not to 100%, so this means the server is always starving. It is waiting on +> something -- of couse not lock. That's why I think there is some problem +> on network communication. Another suspect will be the write - I knwo NTFS +> system will issue an internal log when extending a file. To remove the +> second suspect, I will try to hack the source to do a "fake" write ... +> + +To patch: +------------------------- +Here is a quite straight hack to implement "fake" write for both relation +and xlog. Now the server becomes pure CPU play. + +1. RelationGetBufferForTuple()/hio.c: remove line (if you do not enable +cassert, then doesn't matter): +- Assert(PageIsNew((PageHeader) pageHeader)); + +2. ReadBuffer()/bufmgr.c: remove line +- smgrextend(reln->rd_smgr, blockNum, (char *) bufBlock, +- reln->rd_istemp); + +3. XLogWrite()/xlog.c + errno = 0; ++ goto fake; + if (write(openLogFile, from, nbytes) != nbytes) + { + /* if write didn't set errno, assume no disk space */ + ... + } ++ ++ fake: + /* Update state for write */ + + +To use it: +------------------------- +1. have several copies of a correct data; + +2. patch the server; + +3. when you startup postmaster, use the following parameters: +postmaster -c"checkpoint_timeout=3600" -c"bgwriter_all_percent=0" -Ddata + +Note now the database server is one-shoot usable -- after you shutdown, it +won't startup again. Just run +begin; + many inserts; +end; + +To observe: +------------------------- +(1) In this case, what's the remote server CPU usage -- 100%? I don't have +several machines to test it. In my single machine, I run 35000 insert +commands from psql by cut and paste into it and could observe that: +--- +25% kernel time +75% user time + +20% postgresql (--enable-debug --enable-cassert) +65% psql (as same above) +10% csrss (system process, manage graphics commands (not sure, just googled +it), etc) +5% system (system process) +--- + +(2) In this case, Linux still keeps almost 10 times faster? + +After this, we may need more observations like comparison of simple "select +1;" to reduce the code space we may want to explore ... + +Regards, +Qingqing + + + +From pgsql-performance-owner@postgresql.org Thu Nov 3 23:03:12 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id BA1F5DACD6 + for ; + Thu, 3 Nov 2005 23:03:08 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14538-04 + for ; + Fri, 4 Nov 2005 03:02:55 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id EF770D9FF3 + for ; + Thu, 3 Nov 2005 23:01:56 -0400 (AST) +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr2.postgresql.org (Postfix) with ESMTP id 5BCAEF1A5F + for ; + Thu, 3 Nov 2005 23:57:03 +0000 (GMT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA3NuxJ4007861; + Thu, 3 Nov 2005 18:57:01 -0500 (EST) +To: "Merlin Moncure" +Cc: "Qingqing Zhou" , + pgsql-performance@postgresql.org, "Marc Cousin" +Subject: Re: insert performance for win32 +In-reply-to: <6EE64EF3AB31D5448D0007DD34EEB3417DD79B@Herge.rcsinc.local> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD79B@Herge.rcsinc.local> +Comments: In-reply-to "Merlin Moncure" + message dated "Thu, 03 Nov 2005 13:03:19 -0500" +MIME-Version: 1.0 +Content-Type: multipart/mixed; boundary="----- =_aaaaaaaaaa0" +Content-ID: <7853.1131062168.0@sss.pgh.pa.us> +Date: Thu, 03 Nov 2005 18:56:59 -0500 +Message-ID: <7860.1131062219@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/66 +X-Sequence-Number: 15323 + +------- =_aaaaaaaaaa0 +Content-Type: text/plain; charset="us-ascii" +Content-ID: <7853.1131062168.1@sss.pgh.pa.us> + +"Merlin Moncure" writes: +> ok, I generated a test case which was 250k inserts to simple two column +> table all in single transaction. Every 50k inserts, time is recorded +> via timeofday(). + +You mean something like the attached? + +> Running from remote, Time progression is: +> First 50k: 20 sec +> Second : 29 sec +> [...] +> final: : 66 sec + +On Unix I get a dead flat line (within measurement noise), both local +loopback and across my LAN. + +after 50000 30.20 sec +after 100000 31.67 sec +after 150000 30.98 sec +after 200000 29.64 sec +after 250000 29.83 sec + +"top" shows nearly constant CPU usage over the run, too. With a local +connection it's pretty well pegged, with LAN connection the server's +about 20% idle and the client about 90% (client machine is much faster +than server which may affect this, but I'm too lazy to try it in the +other direction). + +I think it's highly likely that you are looking at some strange behavior +of the Windows TCP stack. + + regards, tom lane + + +------- =_aaaaaaaaaa0 +Content-Type: application/octet-stream +Content-ID: <7853.1131062168.2@sss.pgh.pa.us> +Content-Description: timeit.c + +/* + * testlibpq.c + * + * Test the C version of libpq, the PostgreSQL frontend library. + */ +#include +#include +#include + +#include "libpq-fe.h" + +static void +exit_nicely(PGconn *conn) +{ + PQfinish(conn); + exit(1); +} + +static void +do_cmd(PGconn *conn, const char *cmd) +{ + PGresult *res; + + res = PQexec(conn, cmd); + if (PQresultStatus(res) != PGRES_COMMAND_OK) + { + fprintf(stderr, "%s failed: %s", cmd, PQerrorMessage(conn)); + PQclear(res); + exit_nicely(conn); + } + PQclear(res); +} + +static const char * +rusage_show(const struct timeval *tvold, const struct timeval *tvnew) +{ + static char result[100]; + struct timeval tv = *tvnew; + + if (tv.tv_usec < tvold->tv_usec) + { + tv.tv_sec--; + tv.tv_usec += 1000000; + } + + sprintf(result, + "%d.%02d sec", + (int) (tv.tv_sec - tvold->tv_sec), + (int) (tv.tv_usec - tvold->tv_usec) / 10000); + + return result; +} + +int +main(int argc, char **argv) +{ + const char *conninfo; + PGconn *conn; + char cmdbuf[1024]; + struct timeval tv; + struct timeval tvold; + int i; + + /* + * If the user supplies a parameter on the command line, use it as the + * conninfo string; otherwise default to setting dbname=postgres and using + * environment variables or defaults for all other connection parameters. + */ + if (argc > 1) + conninfo = argv[1]; + else + conninfo = "dbname = postgres"; + + /* Make a connection to the database */ + conn = PQconnectdb(conninfo); + + /* Check to see that the backend connection was successfully made */ + if (PQstatus(conn) != CONNECTION_OK) + { + fprintf(stderr, "Connection to database failed: %s", + PQerrorMessage(conn)); + exit_nicely(conn); + } + + /* Create working table */ + do_cmd(conn, "CREATE TABLE foo (f1 int, f2 int);"); + + /* Start a transaction block */ + do_cmd(conn, "BEGIN"); + + gettimeofday(&tvold, NULL); + + for (i = 1; i <= 250000; i++) + { + sprintf(cmdbuf, "INSERT INTO foo VALUES(%d,%d);", i, i); + do_cmd(conn, cmdbuf); + + if (i % 50000 == 0) + { + gettimeofday(&tv, NULL); + printf("after %d %s\n", i, rusage_show(&tvold, &tv)); + tvold = tv; + } + } + + /* end the transaction */ + do_cmd(conn, "END"); + + /* drop table */ + do_cmd(conn, "DROP TABLE foo;"); + + /* close the connection to the database and cleanup */ + PQfinish(conn); + + return 0; +} + +------- =_aaaaaaaaaa0-- + +From pgsql-performance-owner@postgresql.org Fri Nov 4 03:29:54 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 1C4D8D6824 + for ; + Fri, 4 Nov 2005 03:29:53 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 24847-02 + for ; + Fri, 4 Nov 2005 07:29:49 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from cliff.cs.toronto.edu (cliff.cs.toronto.edu [128.100.3.120]) + by svr1.postgresql.org (Postfix) with ESMTP id F3332D687B + for ; + Fri, 4 Nov 2005 03:29:49 -0400 (AST) +Received: from eon.cs (eon.cs.toronto.edu [128.100.3.15]) + by cliff.cs.toronto.edu (Postfix) with ESMTP id 94C315FD0B; + Fri, 4 Nov 2005 02:29:49 -0500 (EST) +Received: by eon.cs (Postfix, from userid 1300) + id CCFBE698; Fri, 4 Nov 2005 02:29:49 -0500 (EST) +Received: from localhost (localhost [127.0.0.1]) by eon.cs (Postfix) with + ESMTP + id C24FE544; Fri, 4 Nov 2005 02:29:49 -0500 (EST) +Date: Fri, 4 Nov 2005 02:29:49 -0500 (EST) +From: Qingqing Zhou +X-X-Sender: zhouqq@eon.cs +To: Tom Lane +Cc: Merlin Moncure , + pgsql-performance@postgresql.org, Marc Cousin +Subject: Re: insert performance for win32 +In-Reply-To: <7860.1131062219@sss.pgh.pa.us> +Message-ID: +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD79B@Herge.rcsinc.local> + <7860.1131062219@sss.pgh.pa.us> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.362 required=5 tests=[AWL=-0.117, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.362 +X-Spam-Level: +X-Archive-Number: 200511/67 +X-Sequence-Number: 15324 + + + +On Thu, 3 Nov 2005, Tom Lane wrote: + +> +> On Unix I get a dead flat line (within measurement noise), both local +> loopback and across my LAN. +> +> after 50000 30.20 sec +> after 100000 31.67 sec +> after 150000 30.98 sec +> after 200000 29.64 sec +> after 250000 29.83 sec +> + +Confirmed in Linux. And on a winxp machine(sp2) with server, client +together, with (see almost no performance difference) or without my "fake" +write, the observation is still hold for both cases: + +after 50000 25.21 sec +after 100000 26.26 sec +after 150000 25.23 sec +after 200000 26.25 sec +after 250000 26.58 sec + +In both cases, postgres 67% cpu, psql 15~20%, rest: system process. Kernel +time is 40+% -- where from? + +Regards, +Qingqing + +From pgsql-performance-owner@postgresql.org Fri Nov 4 10:45:19 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 398F4D97D6 + for ; + Fri, 4 Nov 2005 10:45:17 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 00574-08 + for ; + Fri, 4 Nov 2005 14:45:10 +0000 (GMT) +X-Greylist: delayed 03:06:39.978367 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 100B9D9437 + for ; + Fri, 4 Nov 2005 10:45:11 -0400 (AST) +Received: from mx.mall.cz (mx.mall.cz [62.168.45.106]) + by svr2.postgresql.org (Postfix) with ESMTP id CC5D3F0F89 + for ; + Fri, 4 Nov 2005 11:38:34 +0000 (GMT) +Received: from localhost (asterix [127.0.0.1]) + by mx.mall.cz (Postfix) with ESMTP id 0B5B113FC02 + for ; + Fri, 4 Nov 2005 12:38:30 +0100 (CET) +Received: from mx.mall.cz ([127.0.0.1]) + by localhost (asterix [127.0.0.1]) (amavisd-new, port 10025) with ESMTP + id 06153-02 for ; + Fri, 4 Nov 2005 12:38:29 +0100 (CET) +Message-ID: <436B4836.7030300@mall.cz> +Date: Fri, 04 Nov 2005 12:38:30 +0100 +From: Michal Taborsky +User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317) +X-Accept-Language: cs, en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Searching union views not using indices +Content-Type: text/plain; charset=ISO-8859-2; format=flowed +Content-Transfer-Encoding: 8bit +X-Virus-Scanned: by amavisd-new at mall.cz +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/70 +X-Sequence-Number: 15327 + +Hello everyone. + +We are facing a performance problem with views consisting of several +unioned tables. The simplified schema is as follows: + +CREATE TABLE foo ( + foo_object_id bigint, + link_id bigint, + somedata text, + PRIMARY KEY (foo_object_id) ); + +CREATE TABLE bar ( + bar_object_id bigint, + link_id bigint, + otherdata real, + PRIMARY KEY (bar_object_id) ); + +There are actually five of such tables, all having two common attributes +*_object_id and link_id. All tables have indices on link_id, which is +very selective, close to unique. The *_object_id is unique within this +scope across all tables, but that's not important. + +Then we have a view: + +CREATE VIEW commonview AS +SELECT foo_object_id as object_id, link_id, 'It is in foo' as loc +FROM foo + +UNION + +SELECT bar_object_id as object_id, link_id, 'It is in bar' as loc +FROM bar + +We commonly do this: + +SELECT object_id FROM commonview WHERE link_id=1234567 + +The result is sequential scan on all tables, append, sort and then +filter scan on this whole thing. Which of course is slow as hell. We use +version 8.0.2. + +And now the question: Is there a way to force the planner to push the +condition lower, so it will use the index? Or do you use some tricks in +this scenario? Thanks for your suggestions. + +Bye. + +-- +Michal T�borsk� +CTO, Internet Mall, a.s. + +Internet Mall - obchody, kter� si obl�b�te + + +From pgsql-performance-owner@postgresql.org Fri Nov 4 09:49:31 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 26052D90CA + for ; + Fri, 4 Nov 2005 09:49:30 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 66150-04 + for ; + Fri, 4 Nov 2005 13:49:26 +0000 (GMT) +X-Greylist: delayed 16:44:44.85214 by SQLgrey- +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 730EFD9045 + for ; + Fri, 4 Nov 2005 09:49:28 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: multipart/mixed; + boundary="----_=_NextPart_001_01C5E146.900B2D40" +Subject: Re: insert performance for win32 +Date: Fri, 4 Nov 2005 08:49:22 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD7BF@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +Thread-Index: AcXg7UM8MlmSCnXPQCG3O58GFmcQdQAWBuDg +From: "Merlin Moncure" +To: "Tom Lane" +Cc: "Qingqing Zhou" , + +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.044 required=5 tests=[AWL=0.044] +X-Spam-Score: 0.044 +X-Spam-Level: +X-Archive-Number: 200511/68 +X-Sequence-Number: 15325 + +This is a multi-part message in MIME format. + +------_=_NextPart_001_01C5E146.900B2D40 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable + +> You mean something like the attached? +not quite: attached is a file to generate test. +to do it: + +psql yadda +\i timeit.sql +\t +\o dump.sql +select make_dump(50000, false); +\q +cat dump.sql | psql -q yadda + +and see what pops out. I had to do it that way because redirecting psql +to dump file caused psql sit forever waiting on more with cpu load... + +Merlin + +------_=_NextPart_001_01C5E146.900B2D40 +Content-Type: application/octet-stream; + name="timeit.sql" +Content-Transfer-Encoding: base64 +Content-Description: timeit.sql +Content-Disposition: attachment; + filename="timeit.sql" + +Y3JlYXRlIG9yIHJlcGxhY2UgZnVuY3Rpb24gbWFrZV9kdW1wKHNjYWxpbmcgaW50ZWdlciwgc2lu +Z2xlX3RyYW5zYWN0aW9uIGJvb2xlYW4pIHJldHVybnMgdGV4dCBhcyANCiQkDQogICAgZGVjbGFy +ZSANCiAgICAgICAgaWkgICAgICAgICAgICAgIGludGVnZXI7DQogICAgICAgIGpqICAgICAgICAg +ICAgICBpbnRlZ2VyOw0KICAgICAgICBrayAgICAgICAgICAgICAgaW50ZWdlciBkZWZhdWx0IDA7 +DQogICAgICAgIGR1bXBfc3FsICAgICAgICB0ZXh0Ow0KICAgICAgICBpbnNlcnRfbGluZXMgICAg +dGV4dCBkZWZhdWx0ICcnOw0KICAgICAgICBzY2FsaW5nX2FkaiAgICAgaW50ZWdlcjsNCiAgICAg +ICAgbWluX2RlbHRhICAgICAgIGludGVnZXIgZGVmYXVsdCAxMDAwOw0KICAgIGJlZ2luDQogICAg +ICAgIGR1bXBfc3FsIDo9ICdkcm9wIHRhYmxlIGJ1bGtfaW5zZXJ0OyBjcmVhdGUgdGFibGUgYnVs +a19pbnNlcnQoaWQgaW50LCBmIHRleHQpO1xuJzsNCiAgICAgICAgZHVtcF9zcWwgOj0gZHVtcF9z +cWwgfHwgJ2JlZ2luO1xuJzsNCiAgICAgICAgZHVtcF9zcWwgOj0gZHVtcF9zcWwgfHwgJ3NlbGVj +dCB0aW1lb2ZkYXkoKTsgXG4nOw0KICAgICAgICANCiAgICAgICAgc2NhbGluZ19hZGogOj0gc2Nh +bGluZyAgLyBtaW5fZGVsdGE7DQogICAgICAgIA0KICAgICAgICBmb3IgaWkgaW4gMS4ubWluX2Rl +bHRhIGxvb3ANCiAgICAgICAgICAgIGluc2VydF9saW5lcyA6PSBpbnNlcnRfbGluZXMgfHwgJ0lO +U0VSVCBJTlRPIGJ1bGtfaW5zZXJ0IFZBTFVFUyAoJyB8fCBrayB8fCANCiAgICAgICAgICAgICAg +ICAgICAnLCBcJycgfHwga2sgfHwgJ1wnKTtcbic7ICAgICAgICAgICAgICAgIA0KICAgICAgICAg +ICAgICAgICAgIA0KICAgICAgICAgICBrayA6PSBrayArIDE7ICAgICAgICAgICAgICAgICAgIA0K +ICAgICAgICBlbmQgbG9vcDsNCiAgICAgICAgDQogICAgICAgIGtrIDo9IDA7DQogICAgICAgIA0K +ICAgICAgICBmb3IgaWkgaW4gMS4uNSBsb29wDQogICAgICAgICAgICBpZiBpaSA+IDEgYW5kIHNp +bmdsZV90cmFuc2FjdGlvbiA9IGZhbHNlIHRoZW4NCiAgICAgICAgICAgICAgICBkdW1wX3NxbCA6 +PSBkdW1wX3NxbCB8fCAnY29tbWl0OyBiZWdpbjtcbic7ICAgDQogICAgICAgICAgICBlbmQgaWY7 +DQogICAgICAgICAgICANCiAgICAgICAgICAgIGZvciBqaiBpbiAxLi5zY2FsaW5nX2FkaiBsb29w +DQogICAgICAgICAgICAgICAgZHVtcF9zcWwgOj0gZHVtcF9zcWwgfHwgaW5zZXJ0X2xpbmVzOw0K +ICAgICAgICAgICAgICAgIGtrIDo9IGtrICsgbWluX2RlbHRhOyAgICAgICAgICAgICAgICAgICAg +DQogICAgICAgICAgICBlbmQgbG9vcDsNCiAgICAgICAgICAgIA0KICAgICAgICAgICAgcmFpc2Ug +bm90aWNlICclIHJvd3MgYWRkZWQnLCBrazsNCiAgICAgICAgICAgIA0KICAgICAgICAgICAgZHVt +cF9zcWwgOj0gZHVtcF9zcWwgfHwgJ3NlbGVjdCB0aW1lb2ZkYXkoKTsgXG4nOw0KICAgICAgICBl +bmQgbG9vcDsNCiAgICAgICAgDQogICAgICAgIGR1bXBfc3FsIDo9IGR1bXBfc3FsIHx8ICdjb21t +aXQ7IFxuJzsNCiAgICAgICAgDQogICAgICAgIHJldHVybiBkdW1wX3NxbDsgICAgICAgDQogICAg +ZW5kOyAgICANCg0KJCQgbGFuZ3VhZ2UgcGxwZ3NxbDs= + +------_=_NextPart_001_01C5E146.900B2D40-- + +From pgsql-performance-owner@postgresql.org Fri Nov 4 10:07:59 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 92DCAD680C + for ; + Fri, 4 Nov 2005 10:07:58 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 70572-08 + for ; + Fri, 4 Nov 2005 14:07:55 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 1786ED680B + for ; + Fri, 4 Nov 2005 10:07:56 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: insert performance for win32 +Date: Fri, 4 Nov 2005 09:08:00 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD7C2@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +Thread-Index: AcXg7UM8MlmSCnXPQCG3O58GFmcQdQAWBuDgAADmBzA= +From: "Merlin Moncure" +To: "Tom Lane" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.043 required=5 tests=[AWL=0.043] +X-Spam-Score: 0.043 +X-Spam-Level: +X-Archive-Number: 200511/69 +X-Sequence-Number: 15326 + +> > You mean something like the attached? + +oh, btw I ran timeit.c and performance is flat and fairly fast. I'm +pretty sure psql is the culprit here. + +Merlin + +From pgsql-performance-owner@postgresql.org Fri Nov 4 10:59:26 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id BD41CD95D5 + for ; + Fri, 4 Nov 2005 10:59:24 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 21296-03 + for ; + Fri, 4 Nov 2005 14:59:21 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 42EEDD95D0 + for ; + Fri, 4 Nov 2005 10:59:22 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA4ExLAK013483; + Fri, 4 Nov 2005 09:59:21 -0500 (EST) +To: "Merlin Moncure" +Cc: "Qingqing Zhou" , pgsql-performance@postgresql.org +Subject: Re: insert performance for win32 +In-reply-to: <6EE64EF3AB31D5448D0007DD34EEB3417DD7BF@Herge.rcsinc.local> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD7BF@Herge.rcsinc.local> +Comments: In-reply-to "Merlin Moncure" + message dated "Fri, 04 Nov 2005 08:49:22 -0500" +Date: Fri, 04 Nov 2005 09:59:20 -0500 +Message-ID: <13482.1131116360@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/71 +X-Sequence-Number: 15328 + +"Merlin Moncure" writes: +>> You mean something like the attached? + +> not quite: attached is a file to generate test. + +> cat dump.sql | psql -q yadda + +Ah. Does your psql have readline support? if so, does adding -n to +that command change anything? + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 4 11:05:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 2B779D979F + for ; + Fri, 4 Nov 2005 11:05:45 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 21967-09 + for ; + Fri, 4 Nov 2005 15:05:41 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.metronet.co.uk (mail.metronet.co.uk [213.162.97.75]) + by svr1.postgresql.org (Postfix) with ESMTP id C267AD982E + for ; + Fri, 4 Nov 2005 11:05:43 -0400 (AST) +Received: from mainbox.archonet.com + (84-51-143-99.archon037.adsl.metronet.co.uk [84.51.143.99]) + by smtp.metronet.co.uk (MetroNet Mail) with ESMTP + id E6D4740C066; Fri, 4 Nov 2005 15:05:20 +0000 (GMT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by mainbox.archonet.com (Postfix) with ESMTP id 407A815EDA; + Fri, 4 Nov 2005 15:01:08 +0000 (GMT) +Received: from mainbox.archonet.com ([127.0.0.1]) + by localhost (mainbox [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id 04715-07; Fri, 4 Nov 2005 15:01:05 +0000 (GMT) +Received: from [192.168.1.17] (client17.office.archonet.com [192.168.1.17]) + by mainbox.archonet.com (Postfix) with ESMTP id A7C8A15ED9; + Fri, 4 Nov 2005 15:01:05 +0000 (GMT) +Message-ID: <436B77B1.7090602@archonet.com> +Date: Fri, 04 Nov 2005 15:01:05 +0000 +From: Richard Huxton +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20051013) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Michal Taborsky +Cc: pgsql-performance@postgresql.org +Subject: Re: Searching union views not using indices +References: <436B4836.7030300@mall.cz> +In-Reply-To: <436B4836.7030300@mall.cz> +Content-Type: text/plain; charset=ISO-8859-2; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.033 required=5 tests=[AWL=0.033] +X-Spam-Score: 0.033 +X-Spam-Level: +X-Archive-Number: 200511/72 +X-Sequence-Number: 15329 + +Michal Taborsky wrote: +... +> UNION +... +> The result is sequential scan on all tables, append, sort and then +> filter scan on this whole thing. Which of course is slow as hell. We use +> version 8.0.2. +> +> And now the question: Is there a way to force the planner to push the +> condition lower, so it will use the index? Or do you use some tricks in +> this scenario? Thanks for your suggestions. + +Try "UNION ALL", since UNION is defined as removing duplicates, which +probably accounts for the sort. + +-- + Richard Huxton + Archonet Ltd + +From pgsql-performance-owner@postgresql.org Fri Nov 4 11:08:02 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id E02D5D9079 + for ; + Fri, 4 Nov 2005 11:08:01 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 21622-10 + for ; + Fri, 4 Nov 2005 15:07:58 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 3C886D8ED6 + for ; + Fri, 4 Nov 2005 11:07:59 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Searching union views not using indices +Date: Fri, 4 Nov 2005 10:07:53 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD7C6@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Searching union views not using indices +Thread-Index: AcXhTubtTeu2pLbtRnqEZkJUmCROXgAAGq6g +From: "Merlin Moncure" +To: "Michal Taborsky" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.043 required=5 tests=[AWL=0.043] +X-Spam-Score: 0.043 +X-Spam-Level: +X-Archive-Number: 200511/73 +X-Sequence-Number: 15330 + +> Hello everyone. +>=20 +> We are facing a performance problem with views consisting of several +> unioned tables. The simplified schema is as follows: +>=20 +> CREATE TABLE foo ( +> foo_object_id bigint, +> link_id bigint, +> somedata text, +> PRIMARY KEY (foo_object_id) ); + +point 1: +well, you may want to consider: + +create table foobar +(=20 + prefix text, -- foo/bar/etc + object_id bigint, + link_id bigint, + primary key(prefix, object_id) +); -- add indexes as appropriate + +and push foo/bar specific information to satellite table which refer +back via pkey-key link. Now you get very quick and easy link id query +and no view is necessary. You also may want to look at table +inheritance but make sure you read all the disclaimers first. + +point 2:=20 +watch out for union, it is implied sort and duplicate filter. union all +is faster although you may get duplicates. + +Merlin + +From pgsql-performance-owner@postgresql.org Fri Nov 4 11:12:23 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 23778D93EB + for ; + Fri, 4 Nov 2005 11:12:21 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 17609-10 + for ; + Fri, 4 Nov 2005 15:12:17 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id AF45FD93CF + for ; + Fri, 4 Nov 2005 11:12:19 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: insert performance for win32 +Date: Fri, 4 Nov 2005 10:12:23 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD7C7@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +Thread-Index: AcXhUFvTQWVQNdjmQbWKM9wSYgUMjAAAMETQ +From: "Merlin Moncure" +To: "Tom Lane" +Cc: , + "Qingqing Zhou" , "Marc Cousin" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.042 required=5 tests=[AWL=0.042] +X-Spam-Score: 0.042 +X-Spam-Level: +X-Archive-Number: 200511/74 +X-Sequence-Number: 15331 + +> > not quite: attached is a file to generate test. +>=20 +> > cat dump.sql | psql -q yadda +>=20 +> Ah. Does your psql have readline support? if so, does adding -n to +> that command change anything? +>=20 + +It doesn't, and it doesn't. :/ Ok, here's where it gets interesting. I +removed all the newlines from the test output (dump.sql) and got flat +times ;). =20 + +Merlin + + +From pgsql-performance-owner@postgresql.org Fri Nov 4 11:14:32 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0E1CCD9079 + for ; + Fri, 4 Nov 2005 11:13:07 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 18686-10 + for ; + Fri, 4 Nov 2005 15:13:03 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id CB3BCD8286 + for ; + Fri, 4 Nov 2005 11:13:05 -0400 (AST) +Received: from tigger.fuhr.org (tigger.fuhr.org [63.214.45.158]) + by svr2.postgresql.org (Postfix) with ESMTP id 5C1A7F13CB + for ; + Fri, 4 Nov 2005 15:13:10 +0000 (GMT) +Received: from winnie.fuhr.org (winnie.fuhr.org [10.1.0.1]) + by tigger.fuhr.org (8.13.3/8.13.3) with ESMTP id jA4FCwvG016968 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); + Fri, 4 Nov 2005 08:13:01 -0700 (MST) + (envelope-from mfuhr@winnie.fuhr.org) +Received: from winnie.fuhr.org (localhost [127.0.0.1]) + by winnie.fuhr.org (8.13.4/8.13.4) with ESMTP id jA4FCwMN089807; + Fri, 4 Nov 2005 08:12:58 -0700 (MST) + (envelope-from mfuhr@winnie.fuhr.org) +Received: (from mfuhr@localhost) + by winnie.fuhr.org (8.13.4/8.13.4/Submit) id jA4FCwgG089806; + Fri, 4 Nov 2005 08:12:58 -0700 (MST) (envelope-from mfuhr) +Date: Fri, 4 Nov 2005 08:12:57 -0700 +From: Michael Fuhr +To: Michal Taborsky +Cc: pgsql-performance@postgresql.org +Subject: Re: Searching union views not using indices +Message-ID: <20051104151257.GA89760@winnie.fuhr.org> +References: <436B4836.7030300@mall.cz> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <436B4836.7030300@mall.cz> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/75 +X-Sequence-Number: 15332 + +On Fri, Nov 04, 2005 at 12:38:30PM +0100, Michal Taborsky wrote: +> SELECT object_id FROM commonview WHERE link_id=1234567 +> +> The result is sequential scan on all tables, append, sort and then +> filter scan on this whole thing. Which of course is slow as hell. We use +> version 8.0.2. + +I couldn't duplicate this in 8.0.4; I don't know if anything's +changed since 8.0.2 that would affect the query plan. Could you +post the EXPLAIN ANALYZE output? It might also be useful to see +the output with enable_seqscan disabled. + +Have the tables been vacuumed and analyzed recently? + +-- +Michael Fuhr + +From pgsql-performance-owner@postgresql.org Fri Nov 4 11:21:47 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 46E51D8C87 + for ; + Fri, 4 Nov 2005 11:21:46 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 32906-07 + for ; + Fri, 4 Nov 2005 15:21:42 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id BCF09D8286 + for ; + Fri, 4 Nov 2005 11:21:44 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA4FLnBg013734; + Fri, 4 Nov 2005 10:21:49 -0500 (EST) +To: "Merlin Moncure" +Cc: pgsql-performance@postgresql.org, "Qingqing Zhou" , + "Marc Cousin" +Subject: Re: insert performance for win32 +In-reply-to: <6EE64EF3AB31D5448D0007DD34EEB3417DD7C7@Herge.rcsinc.local> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD7C7@Herge.rcsinc.local> +Comments: In-reply-to "Merlin Moncure" + message dated "Fri, 04 Nov 2005 10:12:23 -0500" +Date: Fri, 04 Nov 2005 10:21:49 -0500 +Message-ID: <13733.1131117709@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/76 +X-Sequence-Number: 15333 + +"Merlin Moncure" writes: +> It doesn't, and it doesn't. :/ Ok, here's where it gets interesting. I +> removed all the newlines from the test output (dump.sql) and got flat +> times ;). + +That's bizarre ... I'd have thought a very long line would be more +likely to trigger internal performance problems than the original. + +What happens if you read the file with "psql -f dump.sql" instead +of cat/stdin? + +BTW, I get flat times for your psql test case on Unix, again both with +local and remote client. So whatever is going on here, it's +Windows-specific. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 4 11:31:09 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 76202D8286 + for ; + Fri, 4 Nov 2005 11:31:08 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 44913-01 + for ; + Fri, 4 Nov 2005 15:31:04 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id B71ECD6824 + for ; + Fri, 4 Nov 2005 11:31:06 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: insert performance for win32 +Date: Fri, 4 Nov 2005 10:31:11 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD7CB@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +Thread-Index: AcXhU3wOS8GWkDaqRfSLJHAcWq7e9QAAOzHQ +From: "Merlin Moncure" +To: "Tom Lane" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.042 required=5 tests=[AWL=0.042] +X-Spam-Score: 0.042 +X-Spam-Level: +X-Archive-Number: 200511/77 +X-Sequence-Number: 15334 + +> That's bizarre ... I'd have thought a very long line would be more +> likely to trigger internal performance problems than the original. +>=20 +> What happens if you read the file with "psql -f dump.sql" instead +> of cat/stdin? + +non-flat. Also ran via \i and got non flat times. + +> BTW, I get flat times for your psql test case on Unix, again both with +> local and remote client. So whatever is going on here, it's +> Windows-specific. + +yeah. I'm guessing problem is in the mingw flex/bison (which I really, +really hope is not the case) or some other win32 specific block of code. +I'm snooping around there... + +Merlin=20 + +From pgsql-performance-owner@postgresql.org Fri Nov 4 11:31:37 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6AE85D91AD + for ; + Fri, 4 Nov 2005 11:31:35 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 40480-05 + for ; + Fri, 4 Nov 2005 15:31:31 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 9EB43D9135 + for ; + Fri, 4 Nov 2005 11:31:33 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA4FVYjS013816; + Fri, 4 Nov 2005 10:31:34 -0500 (EST) +To: Michal Taborsky +Cc: pgsql-performance@postgresql.org +Subject: Re: Searching union views not using indices +In-reply-to: <436B4836.7030300@mall.cz> +References: <436B4836.7030300@mall.cz> +Comments: In-reply-to Michal Taborsky + message dated "Fri, 04 Nov 2005 12:38:30 +0100" +Date: Fri, 04 Nov 2005 10:31:34 -0500 +Message-ID: <13815.1131118294@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/78 +X-Sequence-Number: 15335 + +Michal Taborsky writes: +> We are facing a performance problem with views consisting of several +> unioned tables. The simplified schema is as follows: + +Perhaps you should show us the real schema, because I cannot duplicate +your complaint on the toy case you show. + +regression=# explain SELECT object_id FROM commonview WHERE link_id=1234567; + QUERY PLAN +------------------------------------------------------------------------------------------------ + Subquery Scan commonview (cost=41.40..41.66 rows=13 width=8) + -> Unique (cost=41.40..41.53 rows=13 width=16) + -> Sort (cost=41.40..41.43 rows=13 width=16) + Sort Key: object_id, link_id, loc + -> Append (cost=0.00..41.16 rows=13 width=16) + -> Subquery Scan "*SELECT* 1" (cost=0.00..17.12 rows=5 width=16) + -> Index Scan using fooi on foo (cost=0.00..17.07 rows=5 width=16) + Index Cond: (link_id = 1234567) + -> Subquery Scan "*SELECT* 2" (cost=0.00..24.04 rows=8 width=16) + -> Index Scan using bari on bar (cost=0.00..23.96 rows=8 width=16) + Index Cond: (link_id = 1234567) +(11 rows) + +(I had to add indexes on link_id to the example, of course.) + +As noted by others, you probably want to be using UNION ALL not UNION, +but that's not the crux of the issue. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 4 11:36:33 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id E7C1AD907C + for ; + Fri, 4 Nov 2005 11:36:31 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 42883-09 + for ; + Fri, 4 Nov 2005 15:36:28 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 49BBAD8F1D + for ; + Fri, 4 Nov 2005 11:36:29 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA4FaYNM013862; + Fri, 4 Nov 2005 10:36:34 -0500 (EST) +To: "Merlin Moncure" +Cc: pgsql-performance@postgresql.org +Subject: Re: insert performance for win32 +In-reply-to: <6EE64EF3AB31D5448D0007DD34EEB3417DD7CB@Herge.rcsinc.local> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD7CB@Herge.rcsinc.local> +Comments: In-reply-to "Merlin Moncure" + message dated "Fri, 04 Nov 2005 10:31:11 -0500" +Date: Fri, 04 Nov 2005 10:36:34 -0500 +Message-ID: <13861.1131118594@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/79 +X-Sequence-Number: 15336 + +"Merlin Moncure" writes: +> yeah. I'm guessing problem is in the mingw flex/bison (which I really, +> really hope is not the case) or some other win32 specific block of code. +> I'm snooping around there... + +Maybe I'm confused here, but I thought we had established that the local +and remote cases behave differently for you? If so I'd suppose that it +must be a networking issue, and there's little point in looking inside +psql. + +If the problem is internal to psql, gprof or similar tool would be +helpful ... got anything like that on Windows? + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 4 11:41:22 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A59EFD919D + for ; + Fri, 4 Nov 2005 11:41:20 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 39861-06 + for ; + Fri, 4 Nov 2005 15:41:16 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 19CB3D90CA + for ; + Fri, 4 Nov 2005 11:41:18 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: insert performance for win32 +Date: Fri, 4 Nov 2005 10:41:23 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD7CD@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +Thread-Index: AcXhVYttMQihlaMCQRKTMrOizW6mCAAADVLg +From: "Merlin Moncure" +To: "Tom Lane" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.041 required=5 tests=[AWL=0.041] +X-Spam-Score: 0.041 +X-Spam-Level: +X-Archive-Number: 200511/80 +X-Sequence-Number: 15337 + +>=20 +> "Merlin Moncure" writes: +> > yeah. I'm guessing problem is in the mingw flex/bison (which I +really, +> > really hope is not the case) or some other win32 specific block of +code. +> > I'm snooping around there... +>=20 +> Maybe I'm confused here, but I thought we had established that the +local +> and remote cases behave differently for you? If so I'd suppose that +it +> must be a networking issue, and there's little point in looking inside +> psql. +>=20 +The local case is *worse*...presumably because psql is competing with +the server for cpu time...cpu load is pegged at 100%. On the remote +case, I'm getting 50-60% cpu load which is way to high. The problem is +definitely in psql. + +Merlin + + +From pgsql-performance-owner@postgresql.org Fri Nov 4 11:56:00 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 11BA9D86FB + for ; + Fri, 4 Nov 2005 11:55:58 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 45971-10 + for ; + Fri, 4 Nov 2005 15:55:53 +0000 (GMT) +X-Greylist: delayed 04:17:25.078739 by SQLgrey- +Received: from mx.mall.cz (mx.mall.cz [62.168.45.106]) + by svr1.postgresql.org (Postfix) with ESMTP id 3B513D7115 + for ; + Fri, 4 Nov 2005 11:55:55 -0400 (AST) +Received: from localhost (asterix [127.0.0.1]) + by mx.mall.cz (Postfix) with ESMTP id 7C2D913FC03; + Fri, 4 Nov 2005 16:55:58 +0100 (CET) +Received: from mx.mall.cz ([127.0.0.1]) + by localhost (asterix [127.0.0.1]) (amavisd-new, port 10025) with ESMTP + id 18148-02; Fri, 4 Nov 2005 16:55:57 +0100 (CET) +Message-ID: <436B848F.5030402@mall.cz> +Date: Fri, 04 Nov 2005 16:55:59 +0100 +From: Michal Taborsky +User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317) +X-Accept-Language: cs, en-us, en +MIME-Version: 1.0 +To: Tom Lane +Cc: pgsql-performance@postgresql.org +Subject: Re: Searching union views not using indices +References: <436B4836.7030300@mall.cz> <13815.1131118294@sss.pgh.pa.us> +In-Reply-To: <13815.1131118294@sss.pgh.pa.us> +Content-Type: text/plain; charset=ISO-8859-2; format=flowed +Content-Transfer-Encoding: 8bit +X-Virus-Scanned: by amavisd-new at mall.cz +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/81 +X-Sequence-Number: 15338 + +Tom Lane napsal(a): +> Michal Taborsky writes: +> +>>We are facing a performance problem with views consisting of several +>>unioned tables. The simplified schema is as follows: +> +> +> Perhaps you should show us the real schema, because I cannot duplicate +> your complaint on the toy case you show. +> As noted by others, you probably want to be using UNION ALL not UNION, +> but that's not the crux of the issue. + +OK. Mystery (sort of) solved. After you told me it works for you I had +to assume the problem was somewhere else. And, indeed, it was, though +it's not too obvious. + +The two attributes are actually not of tybe bigint, but of type +"crm_object_id", which is created as follows: + +CREATE DOMAIN "public"."crm_object_id" AS + bigint NULL; + +Everything started working perfectly after I modified the view like this: + +CREATE VIEW commonview AS +SELECT foo_object_id::bigint as object_id, link_id::bigint, 'It is in +foo' as loc FROM foo +UNION +SELECT bar_object_id::bigint as object_id, link_id::bigint, 'It is in +bar' as loc FROM bar + +Not even modifying the select as this did not help: + +explain SELECT object_id FROM commonview WHERE +link_id=1234567::crm_object_id; + +Is this a bug or feature? + +-- +Michal T�borsk� +CTO, Internet Mall, a.s. + +Internet Mall - obchody, kter� si obl�b�te + + +From pgsql-performance-owner@postgresql.org Fri Nov 4 12:16:53 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CFBA9D6E2A + for ; + Fri, 4 Nov 2005 12:16:52 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 53466-08 + for ; + Fri, 4 Nov 2005 16:16:50 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 31143D680C + for ; + Fri, 4 Nov 2005 12:16:49 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: insert performance for win32 +Date: Fri, 4 Nov 2005 11:16:45 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD7CE@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +Thread-Index: AcXhVYttMQihlaMCQRKTMrOizW6mCAAADVLgAACBfWA= +From: "Merlin Moncure" +To: "Tom Lane" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.041 required=5 tests=[AWL=0.041] +X-Spam-Score: 0.041 +X-Spam-Level: +X-Archive-Number: 200511/82 +X-Sequence-Number: 15339 + +ok, here is gprof output from newlines/no newlines=20 +[newlines] + % cumulative self self total =20 + time seconds seconds calls s/call s/call name =20 + 19.03 0.67 0.67 1 0.67 3.20 MainLoop + 17.61 1.29 0.62 500031 0.00 0.00 yylex + 15.63 1.84 0.55 1500094 0.00 0.00 GetVariable + 11.08 2.23 0.39 250018 0.00 0.00 SendQuery + 4.26 2.38 0.15 750051 0.00 0.00 GetVariableBool + 3.41 2.50 0.12 250024 0.00 0.00 SetVariable + 2.56 2.59 0.09 250015 0.00 0.00 gets_fromFile + 2.27 2.67 0.08 750044 0.00 0.00 +yy_switch_to_buffer + 2.27 2.75 0.08 500031 0.00 0.00 psql_scan + 2.27 2.83 0.08 pg_strcasecmp + 1.70 2.89 0.06 4250078 0.00 0.00 emit + 1.70 2.95 0.06 500031 0.00 0.00 VariableEquals + 1.70 3.01 0.06 250018 0.00 0.00 AcceptResult + 1.42 3.06 0.05 250018 0.00 0.00 ResetCancelConn + +[no newlines] + % cumulative self self total =20 + time seconds seconds calls s/call s/call name =20 + 23.01 0.26 0.26 250019 0.00 0.00 yylex + 19.47 0.48 0.22 250018 0.00 0.00 SendQuery + 11.50 0.61 0.13 1000070 0.00 0.00 GetVariable + 9.73 0.72 0.11 250042 0.00 0.00 pg_strdup + 9.73 0.83 0.11 250024 0.00 0.00 SetVariable + 6.19 0.90 0.07 500039 0.00 0.00 GetVariableBool + 5.31 0.96 0.06 pg_strcasecmp + 4.42 1.01 0.05 4250078 0.00 0.00 emit + 2.65 1.04 0.03 1 0.03 1.01 MainLoop + +ok, mingw gprof is claiming MainLoop is a culprit here, along with +general efficiency penalty otherwise in several things (twice many calls +to yylex, 33%more to getvariable, etc). Just for fun I double checked +string len of query input to SendQuery and everything is the right +length. + +Same # calls to SendQuery, but 2.5 times call time in newlines +case...anything jump out? =20 + +Merlin + +From pgsql-performance-owner@postgresql.org Fri Nov 4 12:33:56 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0EF24D95BA + for ; + Fri, 4 Nov 2005 12:33:55 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 63831-06 + for ; + Fri, 4 Nov 2005 16:33:53 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 699C3D956C + for ; + Fri, 4 Nov 2005 12:33:52 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA4GXqLg014317; + Fri, 4 Nov 2005 11:33:52 -0500 (EST) +To: "Merlin Moncure" +Cc: pgsql-performance@postgresql.org +Subject: Re: insert performance for win32 +In-reply-to: <6EE64EF3AB31D5448D0007DD34EEB3417DD7CE@Herge.rcsinc.local> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD7CE@Herge.rcsinc.local> +Comments: In-reply-to "Merlin Moncure" + message dated "Fri, 04 Nov 2005 11:16:45 -0500" +Date: Fri, 04 Nov 2005 11:33:52 -0500 +Message-ID: <14316.1131122032@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/83 +X-Sequence-Number: 15340 + +"Merlin Moncure" writes: +> ok, mingw gprof is claiming MainLoop is a culprit here, + +The only thing I can see that would be different for Windows is the +SetConsoleCtrlHandler kernel call ... could that be expensive? Why +do we have either sigsetjmp or setup_cancel_handler inside the per-line +loop, rather than just before it? + +There is a lot of stuff in MainLoop that doesn't seem like it really +needs to be done on every single line, particularly not the repeated +fetching of psql variables that couldn't possibly change except inside +HandleSlashCmds. But that all ought to be the same on Unix or Windows. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 4 13:53:13 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A2594D95D5 + for ; + Fri, 4 Nov 2005 13:53:10 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 97114-03 + for ; + Fri, 4 Nov 2005 17:53:09 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 82042D95BA + for ; + Fri, 4 Nov 2005 13:53:08 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA4Hr7lV015834; + Fri, 4 Nov 2005 12:53:07 -0500 (EST) +To: Michal Taborsky +Cc: pgsql-performance@postgresql.org +Subject: Re: Searching union views not using indices +In-reply-to: <436B848F.5030402@mall.cz> +References: <436B4836.7030300@mall.cz> <13815.1131118294@sss.pgh.pa.us> + <436B848F.5030402@mall.cz> +Comments: In-reply-to Michal Taborsky + message dated "Fri, 04 Nov 2005 16:55:59 +0100" +Date: Fri, 04 Nov 2005 12:53:07 -0500 +Message-ID: <15833.1131126787@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/84 +X-Sequence-Number: 15341 + +Michal Taborsky writes: +> OK. Mystery (sort of) solved. After you told me it works for you I had +> to assume the problem was somewhere else. And, indeed, it was, though +> it's not too obvious. + +> The two attributes are actually not of tybe bigint, but of type +> "crm_object_id", which is created as follows: + +> CREATE DOMAIN "public"."crm_object_id" AS +> bigint NULL; + +Ah. The problem is that the UNION's output column is bigint, and the +type discrepancy (bigint above, domain below) discourages the planner +from pushing down the WHERE condition. + +There's a related complaint here: +http://archives.postgresql.org/pgsql-bugs/2005-10/msg00227.php + +If we were to change things so that the result of the UNION were still +the domain, not plain bigint, then your example would be optimized the +way you want. I'm unsure about what other side-effects that would have +though. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 4 13:56:13 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id F214DD680B + for ; + Fri, 4 Nov 2005 13:56:11 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 95567-06 + for ; + Fri, 4 Nov 2005 17:56:09 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 2292ED9135 + for ; + Fri, 4 Nov 2005 13:56:08 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: insert performance for win32 +Date: Fri, 4 Nov 2005 12:56:02 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD7D3@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +Thread-Index: AcXhVYttMQihlaMCQRKTMrOizW6mCAAADVLgAACBfWAAA+/0MA== +From: "Merlin Moncure" +To: "Tom Lane" +Cc: , + "Marc Cousin" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.04 required=5 tests=[AWL=0.040] +X-Spam-Score: 0.04 +X-Spam-Level: +X-Archive-Number: 200511/85 +X-Sequence-Number: 15342 + +Nailed it. + +problem is in mainloop.c -> setup_cancel_handler. Apparently you can +have multiple handlers and windows keeps track of them all, even if they +do the same thing. Keeping track of so many system handles would +naturally slow the whole process down. Commenting that line times are +flat as a pancake. I am thinking keeping track of a global flag would +be appropriate. =20 + + +Merlin + + +From pgsql-performance-owner@postgresql.org Fri Nov 4 14:01:23 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 1E84CD93EB; + Fri, 4 Nov 2005 14:01:22 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 02236-03; Fri, 4 Nov 2005 18:01:20 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 928E5D9385; + Fri, 4 Nov 2005 14:01:20 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA4I1KVM015927; + Fri, 4 Nov 2005 13:01:20 -0500 (EST) +To: "Merlin Moncure" +Cc: pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org +Subject: Re: insert performance for win32 +In-reply-to: <6EE64EF3AB31D5448D0007DD34EEB3417DD7D3@Herge.rcsinc.local> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD7D3@Herge.rcsinc.local> +Comments: In-reply-to "Merlin Moncure" + message dated "Fri, 04 Nov 2005 12:56:02 -0500" +Date: Fri, 04 Nov 2005 13:01:20 -0500 +Message-ID: <15926.1131127280@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/86 +X-Sequence-Number: 15343 + +"Merlin Moncure" writes: +> Nailed it. + +> problem is in mainloop.c -> setup_cancel_handler. Apparently you can +> have multiple handlers and windows keeps track of them all, even if they +> do the same thing. Keeping track of so many system handles would +> naturally slow the whole process down. + +Yipes. So we really want to do that only once. + +AFAICS it is appropriate to move the sigsetjmp and setup_cancel_handler +calls in front of the per-line loop inside MainLoop --- can anyone see +a reason not to? + +I'm inclined to treat this as an outright bug, not just a minor +performance issue, because it implies that a sufficiently long psql +script would probably crash a Windows machine. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 4 14:07:28 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A8350D680C; + Fri, 4 Nov 2005 14:07:26 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 06722-03; Fri, 4 Nov 2005 18:07:25 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 2727CD680B; + Fri, 4 Nov 2005 14:07:24 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: insert performance for win32 +Date: Fri, 4 Nov 2005 13:07:24 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD7D5@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +Thread-Index: AcXhacQhRlD0sR6fT/6Q3scJ1LkFkwAAEtKg +From: "Merlin Moncure" +To: "Tom Lane" +Cc: , + +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.04 required=5 tests=[AWL=0.040] +X-Spam-Score: 0.04 +X-Spam-Level: +X-Archive-Number: 200511/87 +X-Sequence-Number: 15344 + +> "Merlin Moncure" writes: +> > Nailed it. +>=20 +> > problem is in mainloop.c -> setup_cancel_handler. Apparently you +can +> > have multiple handlers and windows keeps track of them all, even if +they +> > do the same thing. Keeping track of so many system handles would +> > naturally slow the whole process down. +>=20 +> Yipes. So we really want to do that only once. +>=20 +> AFAICS it is appropriate to move the sigsetjmp and +setup_cancel_handler +> calls in front of the per-line loop inside MainLoop --- can anyone see +> a reason not to? + +hm. mainloop is re-entrant, right? That means each \i would reset the +handler...what is downside to keeping global flag? + + +> I'm inclined to treat this as an outright bug, not just a minor +certainly... + +> performance issue, because it implies that a sufficiently long psql +> script would probably crash a Windows machine. + +actually, it's worse than that, it's more of a dos on the whole system, +as windows will eventually stop granting handles, but there is a good +chance of side effects on other applications. + +Merlin + +From pgsql-hackers-owner@postgresql.org Fri Nov 4 14:14:42 2005 +X-Original-To: pgsql-hackers-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 2DB1ED8ED6; + Fri, 4 Nov 2005 14:14:40 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 06797-03; Fri, 4 Nov 2005 18:14:37 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 7945CD680C; + Fri, 4 Nov 2005 14:14:37 -0400 (AST) +Received: from fetter.org (dsl092-188-065.sfo1.dsl.speakeasy.net + [66.92.188.65]) + by svr2.postgresql.org (Postfix) with ESMTP id D9E2DF131B; + Fri, 4 Nov 2005 18:14:35 +0000 (GMT) +Received: from fetter.org (localhost.localdomain [127.0.0.1]) + by fetter.org (8.13.4/8.12.10) with ESMTP id jA4IEVIl005015; + Fri, 4 Nov 2005 10:14:32 -0800 +Received: (from shackle@localhost) + by fetter.org (8.13.4/8.13.4/Submit) id jA4IEVt7005014; + Fri, 4 Nov 2005 10:14:31 -0800 +Date: Fri, 4 Nov 2005 10:14:31 -0800 +From: David Fetter +To: Tom Lane +Cc: Merlin Moncure , + pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org +Subject: Re: [PERFORM] insert performance for win32 +Message-ID: <20051104181431.GA4017@fetter.org> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD7D3@Herge.rcsinc.local> + <15926.1131127280@sss.pgh.pa.us> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <15926.1131127280@sss.pgh.pa.us> +User-Agent: Mutt/1.4.2.1i +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.05 required=5 tests=[AWL=0.050] +X-Spam-Score: 0.05 +X-Spam-Level: +X-Archive-Number: 200511/162 +X-Sequence-Number: 75444 + +On Fri, Nov 04, 2005 at 01:01:20PM -0500, Tom Lane wrote: +> "Merlin Moncure" writes: +> > Nailed it. +> +> > problem is in mainloop.c -> setup_cancel_handler. Apparently you +> > can have multiple handlers and windows keeps track of them all, +> > even if they do the same thing. Keeping track of so many system +> > handles would naturally slow the whole process down. +> +> Yipes. So we really want to do that only once. +> +> AFAICS it is appropriate to move the sigsetjmp and +> setup_cancel_handler calls in front of the per-line loop inside +> MainLoop --- can anyone see a reason not to? +> +> I'm inclined to treat this as an outright bug, not just a minor +> performance issue, because it implies that a sufficiently long psql +> script would probably crash a Windows machine. + +Ouch. In light of this, are we *sure* what we've got a is a candidate +for release? + +Cheers, +D +-- +David Fetter david@fetter.org http://fetter.org/ +phone: +1 510 893 6100 mobile: +1 415 235 3778 + +Remember to vote! + +From pgsql-performance-owner@postgresql.org Fri Nov 4 14:14:45 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 1D241D6E2A; + Fri, 4 Nov 2005 14:14:39 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 06398-07; Fri, 4 Nov 2005 18:14:36 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 9F017D680B; + Fri, 4 Nov 2005 14:14:36 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA4IEa0U016057; + Fri, 4 Nov 2005 13:14:36 -0500 (EST) +To: "Merlin Moncure" +Cc: pgsql-hackers@postgresql.org, pgsql-performance@postgresql.org +Subject: Re: insert performance for win32 +In-reply-to: <6EE64EF3AB31D5448D0007DD34EEB3417DD7D5@Herge.rcsinc.local> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD7D5@Herge.rcsinc.local> +Comments: In-reply-to "Merlin Moncure" + message dated "Fri, 04 Nov 2005 13:07:24 -0500" +Date: Fri, 04 Nov 2005 13:14:36 -0500 +Message-ID: <16056.1131128076@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/88 +X-Sequence-Number: 15345 + +"Merlin Moncure" writes: +>> AFAICS it is appropriate to move the sigsetjmp and +>> setup_cancel_handler +>> calls in front of the per-line loop inside MainLoop --- can anyone see +>> a reason not to? + +> hm. mainloop is re-entrant, right? That means each \i would reset the +> handler...what is downside to keeping global flag? + +Ah, right, and in fact I'd missed the comment at line 325 pointing out +that we're relying on the sigsetjmp to be re-executed every time +through. That could be improved on, likely, but not right before a +release. + +Does the flag need to be global? I'm thinking + + void + setup_cancel_handler(void) + { ++ static bool done = false; ++ ++ if (!done) + SetConsoleCtrlHandler(consoleHandler, TRUE); ++ done = true; + } + + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 4 14:15:47 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 108AED91AD; + Fri, 4 Nov 2005 14:15:46 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 06251-07; Fri, 4 Nov 2005 18:15:44 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from candle.pha.pa.us (candle.pha.pa.us [64.139.89.126]) + by svr1.postgresql.org (Postfix) with ESMTP id 1D290D9079; + Fri, 4 Nov 2005 14:15:43 -0400 (AST) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.11.6) id jA4IFhX16474; + Fri, 4 Nov 2005 13:15:43 -0500 (EST) +From: Bruce Momjian +Message-Id: <200511041815.jA4IFhX16474@candle.pha.pa.us> +Subject: Re: insert performance for win32 +In-Reply-To: <15926.1131127280@sss.pgh.pa.us> +To: Tom Lane +Date: Fri, 4 Nov 2005 13:15:43 -0500 (EST) +Cc: Merlin Moncure , + pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org +X-Mailer: ELM [version 2.4ME+ PL121 (25)] +MIME-Version: 1.0 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.014 required=5 tests=[AWL=0.014] +X-Spam-Score: 0.014 +X-Spam-Level: +X-Archive-Number: 200511/89 +X-Sequence-Number: 15346 + +Tom Lane wrote: +> "Merlin Moncure" writes: +> > Nailed it. +> +> > problem is in mainloop.c -> setup_cancel_handler. Apparently you can +> > have multiple handlers and windows keeps track of them all, even if they +> > do the same thing. Keeping track of so many system handles would +> > naturally slow the whole process down. +> +> Yipes. So we really want to do that only once. +> +> AFAICS it is appropriate to move the sigsetjmp and setup_cancel_handler +> calls in front of the per-line loop inside MainLoop --- can anyone see +> a reason not to? + +Nope. + +> I'm inclined to treat this as an outright bug, not just a minor +> performance issue, because it implies that a sufficiently long psql +> script would probably crash a Windows machine. + +Agreed. + +-- + Bruce Momjian | http://candle.pha.pa.us + pgman@candle.pha.pa.us | (610) 359-1001 + + If your life is a hard drive, | 13 Roberts Road + + Christ can be your backup. | Newtown Square, Pennsylvania 19073 + +From pgsql-performance-owner@postgresql.org Fri Nov 4 14:19:06 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 966C6D9079 + for ; + Fri, 4 Nov 2005 14:19:04 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 07008-06 + for ; + Fri, 4 Nov 2005 18:19:03 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 0B7DDD8ED6 + for ; + Fri, 4 Nov 2005 14:19:01 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA4IJ2R8016128; + Fri, 4 Nov 2005 13:19:02 -0500 (EST) +To: David Fetter +Cc: Merlin Moncure , + pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org +Subject: Re: [HACKERS] insert performance for win32 +In-reply-to: <20051104181431.GA4017@fetter.org> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD7D3@Herge.rcsinc.local> + <15926.1131127280@sss.pgh.pa.us> <20051104181431.GA4017@fetter.org> +Comments: In-reply-to David Fetter + message dated "Fri, 04 Nov 2005 10:14:31 -0800" +Date: Fri, 04 Nov 2005 13:19:02 -0500 +Message-ID: <16127.1131128342@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/90 +X-Sequence-Number: 15347 + +David Fetter writes: +> On Fri, Nov 04, 2005 at 01:01:20PM -0500, Tom Lane wrote: +>> I'm inclined to treat this as an outright bug, not just a minor +>> performance issue, because it implies that a sufficiently long psql +>> script would probably crash a Windows machine. + +> Ouch. In light of this, are we *sure* what we've got a is a candidate +> for release? + +Sure. This problem exists in 8.0.* too. Pre-existing bugs don't +disqualify an RC in my mind --- we fix them and move on, same as we +would do at any other time. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 4 14:21:07 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6395BD9357; + Fri, 4 Nov 2005 14:21:05 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 12378-01; Fri, 4 Nov 2005 18:21:03 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mx-2.sollentuna.net (mx-2.sollentuna.net [195.84.163.199]) + by svr1.postgresql.org (Postfix) with ESMTP id A0669D92B7; + Fri, 4 Nov 2005 14:21:02 -0400 (AST) +Received: from ALGOL.sollentuna.se (janus.sollentuna.se [62.65.68.67]) + by mx-2.sollentuna.net (Postfix) with ESMTP + id C0A058F299; Fri, 4 Nov 2005 19:21:01 +0100 (CET) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Subject: Re: insert performance for win32 +Date: Fri, 4 Nov 2005 19:21:02 +0100 +Message-ID: <6BCB9D8A16AC4241919521715F4D8BCE92E7F6@algol.sollentuna.se> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] insert performance for win32 +thread-index: AcXhacQhRlD0sR6fT/6Q3scJ1LkFkwAAEtKgAACIR8A= +From: "Magnus Hagander" +To: "Merlin Moncure" , + "Tom Lane" +Cc: , + +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.033 required=5 tests=[AWL=0.033] +X-Spam-Score: 0.033 +X-Spam-Level: +X-Archive-Number: 200511/91 +X-Sequence-Number: 15348 + +> > I'm inclined to treat this as an outright bug, not just a minor +> certainly... +>=20 +> > performance issue, because it implies that a sufficiently long psql=20 +> > script would probably crash a Windows machine. +>=20 +> actually, it's worse than that, it's more of a dos on the=20 +> whole system, as windows will eventually stop granting=20 +> handles, but there is a good chance of side effects on other=20 +> applications. + +Does it actually use up *handles* there? I don't see anything in the +docs that says it should do that - and they usually do document when +handles are used. You should be seeing a *huge* increase in system +handles very fast if it does, right?=20 + +That said, I definitly agree with calling it a bug :-) + +//Magnus + +From pgsql-performance-owner@postgresql.org Fri Nov 4 14:21:13 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0F6BAD9079; + Fri, 4 Nov 2005 14:21:11 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 06365-10; Fri, 4 Nov 2005 18:21:09 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from candle.pha.pa.us (candle.pha.pa.us [64.139.89.126]) + by svr1.postgresql.org (Postfix) with ESMTP id D6452D680C; + Fri, 4 Nov 2005 14:21:08 -0400 (AST) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.11.6) id jA4IL7117478; + Fri, 4 Nov 2005 13:21:07 -0500 (EST) +From: Bruce Momjian +Message-Id: <200511041821.jA4IL7117478@candle.pha.pa.us> +Subject: Re: [HACKERS] insert performance for win32 +In-Reply-To: <20051104181431.GA4017@fetter.org> +To: David Fetter +Date: Fri, 4 Nov 2005 13:21:07 -0500 (EST) +Cc: Tom Lane , + Merlin Moncure , + pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org +X-Mailer: ELM [version 2.4ME+ PL121 (25)] +MIME-Version: 1.0 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.014 required=5 tests=[AWL=0.014] +X-Spam-Score: 0.014 +X-Spam-Level: +X-Archive-Number: 200511/92 +X-Sequence-Number: 15349 + +David Fetter wrote: +> On Fri, Nov 04, 2005 at 01:01:20PM -0500, Tom Lane wrote: +> > "Merlin Moncure" writes: +> > > Nailed it. +> > +> > > problem is in mainloop.c -> setup_cancel_handler. Apparently you +> > > can have multiple handlers and windows keeps track of them all, +> > > even if they do the same thing. Keeping track of so many system +> > > handles would naturally slow the whole process down. +> > +> > Yipes. So we really want to do that only once. +> > +> > AFAICS it is appropriate to move the sigsetjmp and +> > setup_cancel_handler calls in front of the per-line loop inside +> > MainLoop --- can anyone see a reason not to? +> > +> > I'm inclined to treat this as an outright bug, not just a minor +> > performance issue, because it implies that a sufficiently long psql +> > script would probably crash a Windows machine. +> +> Ouch. In light of this, are we *sure* what we've got a is a candidate +> for release? + +Good point. It is something we would fix in a minor release, so it +doesn't seem worth doing another RC just for that. + +-- + Bruce Momjian | http://candle.pha.pa.us + pgman@candle.pha.pa.us | (610) 359-1001 + + If your life is a hard drive, | 13 Roberts Road + + Christ can be your backup. | Newtown Square, Pennsylvania 19073 + +From pgsql-performance-owner@postgresql.org Fri Nov 4 14:30:37 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6F231D9749; + Fri, 4 Nov 2005 14:30:35 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14425-05; Fri, 4 Nov 2005 18:30:33 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mx-2.sollentuna.net (mx-2.sollentuna.net [195.84.163.199]) + by svr1.postgresql.org (Postfix) with ESMTP id 9575AD95FE; + Fri, 4 Nov 2005 14:30:33 -0400 (AST) +Received: from ALGOL.sollentuna.se (janus.sollentuna.se [62.65.68.67]) + by mx-2.sollentuna.net (Postfix) with ESMTP + id E7E088F299; Fri, 4 Nov 2005 19:30:33 +0100 (CET) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Subject: Re: [HACKERS] insert performance for win32 +Date: Fri, 4 Nov 2005 19:30:32 +0100 +Message-ID: <6BCB9D8A16AC4241919521715F4D8BCE92E7F7@algol.sollentuna.se> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [HACKERS] [PERFORM] insert performance for win32 +thread-index: AcXhbIxUbQmkSlqFTk6zKlH2C3XLbQAARx6Q +From: "Magnus Hagander" +To: "Tom Lane" , + "Merlin Moncure" +Cc: , + +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.033 required=5 tests=[AWL=0.033] +X-Spam-Score: 0.033 +X-Spam-Level: +X-Archive-Number: 200511/94 +X-Sequence-Number: 15351 + +> >> AFAICS it is appropriate to move the sigsetjmp and=20 +> >> setup_cancel_handler calls in front of the per-line loop inside=20 +> >> MainLoop --- can anyone see a reason not to? +>=20 +> > hm. mainloop is re-entrant, right? That means each \i=20 +> would reset the=20 +> > handler...what is downside to keeping global flag? +>=20 +> Ah, right, and in fact I'd missed the comment at line 325=20 +> pointing out that we're relying on the sigsetjmp to be=20 +> re-executed every time through. That could be improved on,=20 +> likely, but not right before a release. +>=20 +> Does the flag need to be global? I'm thinking +>=20 +> void +> setup_cancel_handler(void) +> { +> + static bool done =3D false; +> + +> + if (!done) +> SetConsoleCtrlHandler(consoleHandler, TRUE); +> + done =3D true; +> } +>=20 + +Seems like a simple enough solution, don't see why it shouldn't work. As +long as psql is single-threaded, which it is... +(Actually, that code seems to re-set done=3Dtrue on every call which = +seems +unnecessary - but that might be optimised away, I guess) + +//Magnus + + +From pgsql-performance-owner@postgresql.org Fri Nov 4 14:30:28 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 2868AD8ED6 + for ; + Fri, 4 Nov 2005 14:30:27 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14425-04 + for ; + Fri, 4 Nov 2005 18:30:24 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 73186D8032 + for ; + Fri, 4 Nov 2005 14:30:24 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id C08E831059; Fri, 4 Nov 2005 19:30:24 +0100 (MET) +From: "Qingqing Zhou" +X-Newsgroups: pgsql.performance +Subject: Re: insert performance for win32 +Date: Fri, 4 Nov 2005 13:30:34 -0500 +Organization: Hub.Org Networking Services +Lines: 31 +Message-ID: +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD7CE@Herge.rcsinc.local> +X-Complaints-To: usenet@news.hub.org +X-Priority: 3 +X-MSMail-Priority: Normal +X-Newsreader: Microsoft Outlook Express 6.00.2900.2180 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 +X-RFC2646: Format=Flowed; Original +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.558 required=5 tests=[AWL=0.558] +X-Spam-Score: 0.558 +X-Spam-Level: +X-Archive-Number: 200511/93 +X-Sequence-Number: 15350 + + +""Merlin Moncure"" wrote +> ok, here is gprof output from newlines/no newlines +> [newlines] +> % cumulative self self total +> time seconds seconds calls s/call s/call name +> 19.03 0.67 0.67 1 0.67 3.20 MainLoop +> 17.61 1.29 0.62 500031 0.00 0.00 yylex +> 15.63 1.84 0.55 1500094 0.00 0.00 GetVariable +> 11.08 2.23 0.39 250018 0.00 0.00 SendQuery +> 4.26 2.38 0.15 750051 0.00 0.00 GetVariableBool +> 3.41 2.50 0.12 250024 0.00 0.00 SetVariable +> 2.56 2.59 0.09 250015 0.00 0.00 gets_fromFile +> 2.27 2.67 0.08 750044 0.00 0.00 +> yy_switch_to_buffer +> 2.27 2.75 0.08 500031 0.00 0.00 psql_scan +> 2.27 2.83 0.08 pg_strcasecmp +> 1.70 2.89 0.06 4250078 0.00 0.00 emit +> 1.70 2.95 0.06 500031 0.00 0.00 VariableEquals +> 1.70 3.01 0.06 250018 0.00 0.00 AcceptResult +> 1.42 3.06 0.05 250018 0.00 0.00 ResetCancelConn +> + +Maybe I missed some threads .... do you think it is interesting to test the +*absoulte* time difference of the same machine on Windows/Linux by using +timeit.c? I wonder if windows is slower than Linux ... + +Regards, +Qingqing + + + +From pgsql-performance-owner@postgresql.org Fri Nov 4 18:17:13 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id AC61AD976D + for ; + Fri, 4 Nov 2005 18:17:12 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 09154-08 + for ; + Fri, 4 Nov 2005 22:17:08 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 99E49D999D + for ; + Fri, 4 Nov 2005 18:17:09 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id 12D4B31059; Fri, 4 Nov 2005 23:17:11 +0100 (MET) +From: "Qingqing Zhou" +X-Newsgroups: pgsql.performance +Subject: Re: insert performance for win32 +Date: Fri, 4 Nov 2005 17:17:21 -0500 +Organization: Hub.Org Networking Services +Lines: 21 +Message-ID: +References: <6BCB9D8A16AC4241919521715F4D8BCE92E7F1@algol.sollentuna.se> +X-Complaints-To: usenet@news.hub.org +X-Priority: 3 +X-MSMail-Priority: Normal +X-Newsreader: Microsoft Outlook Express 6.00.2900.2180 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 +X-RFC2646: Format=Flowed; Original +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.555 required=5 tests=[AWL=0.555] +X-Spam-Score: 0.555 +X-Spam-Level: +X-Archive-Number: 200511/95 +X-Sequence-Number: 15352 + + +""Magnus Hagander"" wrote +>> +>> I'd like to use the win32 provided recv(), send() functions +>> instead of redirect them to pgwin32_recv()/pgwin32_send(), +>> just like libpq does. If we do this, we will lose some +>> functionalities, but I'd like to see the performance +>> difference first. -- do you think that will be any difference? +> +> I doubt there will be much performance difference, as you hav eto hit +> the kernel anyway (in the recv/send call). But that part is just a guess +> :-) +> + +On a separate line -- I verified Magnus's doubt -- revert pgwin32_recv() to +recv() does not improve performance visiblly. + +Regards, +Qingqing + + + +From pgsql-performance-owner@postgresql.org Sun Nov 6 05:02:38 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id C9334DA6F4; + Sun, 6 Nov 2005 05:02:35 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 94330-02; Sun, 6 Nov 2005 09:02:33 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtp.nildram.co.uk (smtp.nildram.co.uk [195.112.4.54]) + by svr1.postgresql.org (Postfix) with ESMTP id 47ACED79D9; + Sun, 6 Nov 2005 05:02:34 -0400 (AST) +Received: from 192.168.0.3 (unknown [84.12.200.148]) + by smtp.nildram.co.uk (Postfix) with ESMTP + id 03022252C69; Sun, 6 Nov 2005 09:02:34 +0000 (GMT) +Subject: Re: [HACKERS] insert performance for win32 +From: Simon Riggs +To: Bruce Momjian +Cc: David Fetter , Tom Lane , + Merlin Moncure , + pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org +In-Reply-To: <200511041821.jA4IL7117478@candle.pha.pa.us> +References: <200511041821.jA4IL7117478@candle.pha.pa.us> +Content-Type: text/plain +Organization: 2nd Quadrant +Date: Sun, 06 Nov 2005 09:00:05 +0000 +Message-Id: <1131267605.8300.2055.camel@localhost.localdomain> +Mime-Version: 1.0 +X-Mailer: Evolution 2.0.2 (2.0.2-3) +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.01 required=5 tests=[AWL=0.010] +X-Spam-Score: 0.01 +X-Spam-Level: +X-Archive-Number: 200511/96 +X-Sequence-Number: 15353 + +On Fri, 2005-11-04 at 13:21 -0500, Bruce Momjian wrote: +> David Fetter wrote: +> > On Fri, Nov 04, 2005 at 01:01:20PM -0500, Tom Lane wrote: +> > > I'm inclined to treat this as an outright bug, not just a minor +> > > performance issue, because it implies that a sufficiently long psql +> > > script would probably crash a Windows machine. +> > +> > Ouch. In light of this, are we *sure* what we've got a is a candidate +> > for release? +> +> Good point. It is something we would fix in a minor release, so it +> doesn't seem worth doing another RC just for that. + +Will this be documented in the release notes? If we put unimplemented +features in TODO, where do we list things we regard as bugs? + +Best Regards, Simon Riggs + + +From pgsql-performance-owner@postgresql.org Sun Nov 6 07:06:59 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 800BEDA7CE + for ; + Sun, 6 Nov 2005 07:06:57 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 55107-05 + for ; + Sun, 6 Nov 2005 11:06:54 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id ADA25DA54A + for ; + Sun, 6 Nov 2005 07:06:55 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id C254131059; Sun, 6 Nov 2005 12:06:55 +0100 (MET) +From: "PostgreSQL" +X-Newsgroups: pgsql.performance +Subject: 8.1 iss +Date: Sun, 6 Nov 2005 03:55:18 -0600 +Organization: Hub.Org Networking Services +Lines: 43 +Message-ID: +X-Complaints-To: usenet@news.hub.org +X-Priority: 3 +X-MSMail-Priority: Normal +X-Newsreader: Microsoft Outlook Express 6.00.2900.2670 +X-RFC2646: Format=Flowed; Original +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2670 +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/97 +X-Sequence-Number: 15354 + +SELECT v_barcode, count(v_barcode) FROM lead GROUP BY v_barcode HAVING +count(*) > 1; + +This is a pretty good example of the place where 8.1 seems to be quite +broken. I understand that this query will want to do a full table scan +(even through v_barcode is indexed). And the table is largish, at 34 +million rows. In the 8.0 world, this took around 4 minutes. With 8.1beta3, +this has run for 30 minutes (as I began to write this) and is still going +strong. + +And it behaves differently than I'd expect. Top shows the postmaster +process running the query as using up 99.9 percent of one CPU, while the i/o +wait time never gets above 3%. vmstat shows the "block out" (bo) number +quite high, 15 to 20 thousand, which also surprises me. "block in" is from +0 to about 2500. iostat shows 15,000 to 20,000 blocks written every 5 +seconds, while it shows 0 blocks read. There is no other significant +process running on the box. (Apache is running but is not being used here a +3:00a.m. on Sunday). This is a dual Opteron box with 16 Gb memory and a +3ware SATA raid runing 64bit SUSE. Something seems badly wrong. + +As I post this, the query is approaching an hour of run time. I've listed +an explain of the query and my non-default conf parameters below. Please +advise on anything I should change or try, or on any information I can +provide that could help diagnose this. + + +GroupAggregate (cost=9899282.83..10285434.26 rows=223858 width=15) + Filter: (count(*) > 1) + -> Sort (cost=9899282.83..9994841.31 rows=38223392 width=15) + Sort Key: v_barcode + -> Seq Scan on lead (cost=0.00..1950947.92 rows=38223392 width=15) + +shared_buffers = 50000 +work_mem = 16384 +maintenance_work_mem = 16384 +max_fsm_pages = 100000 +max_fsm_relations = 5000 +wal_buffers = 32 +checkpoint_segments = 32 +effective_cache_size = 50000 +default_statistics_target = 50 + + + +From pgsql-performance-owner@postgresql.org Sun Nov 6 09:31:06 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 782CAD6876 + for ; + Sun, 6 Nov 2005 09:31:05 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 05349-05 + for ; + Sun, 6 Nov 2005 13:30:59 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from obelix.askesis.nl (laudanum.demon.nl [82.161.125.16]) + by svr1.postgresql.org (Postfix) with ESMTP id E9B34D6862 + for ; + Sun, 6 Nov 2005 09:30:59 -0400 (AST) +Received: obelix.askesis.nl 172.31.0.1 from 172.31.1.8 172.31.1.8 via HTTP + with MS-WebStorage 6.0.6249 +Received: from Panoramix by obelix.askesis.nl; 06 Nov 2005 14:31:02 +0100 +Subject: Performance PG 8.0 on dual opteron / 4GB / 3ware Raid5 / Debian?? +From: Joost Kraaijeveld +To: Pgsql-Performance +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Sun, 06 Nov 2005 14:30:54 +0100 +Message-Id: <1131283854.15471.4.camel@Panoramix> +Mime-Version: 1.0 +X-Mailer: Evolution 2.0.4 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.06 required=5 tests=[AWL=0.059, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.06 +X-Spam-Level: +X-Archive-Number: 200511/98 +X-Sequence-Number: 15355 + +Hi, + +I am experiencing very long update queries and I want to know if it +reasonable to expect them to perform better. + +The query below is running for more than 1.5 hours (5500 seconds) now, +while the rest of the system does nothing (I don't even type or move a +mouse...). + +- Is that to be expected? +- Is 180-200 tps with ~ 9000 KB (see output iostat below) not low, given +the fact that fsync is off? (Note: with bonnie++ I get write +performance > 50 MB/sec and read performace > 70 MB/sec with > 2000 +read/write ops /sec? +- Does anyone else have any experience with the 3Ware RAID controller +(which is my suspect)? +- Any good idea how to determine the real botleneck if this is not the +performance I can expect? + +My hard- and software: + +- PostgreSQL 8.0.3 +- Debian 3.1 (Sarge) AMD64 +- Dual Opteron +- 4GB RAM +- 3ware Raid5 with 5 disks + +Pieces of my postgresql.conf (All other is default): +shared_buffers = 7500 +work_mem = 260096 +fsync=false +effective_cache_size = 32768 + + + +The query with explain (amount and orderbedrag_valuta are float8, +ordernummer and ordernumber int4): + +explain update prototype.orders set amount = +odbc.orders.orderbedrag_valuta from odbc.orders where ordernumber = +odbc.orders.ordernummer; + QUERY PLAN +----------------------------------------------------------------------------- +Hash Join (cost=50994.74..230038.17 rows=1104379 width=466) + Hash Cond: ("outer".ordernumber = "inner".ordernummer) + -> Seq Scan on orders (cost=0.00..105360.68 rows=3991868 width=455) + -> Hash (cost=48233.79..48233.79 rows=1104379 width=15) + -> Seq Scan on orders (cost=0.00..48233.79 rows=1104379 +width=15) + + +Sample output from iostat during query (about avarage): +Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn +hdc 0.00 0.00 0.00 0 0 +sda 0.00 0.00 0.00 0 0 +sdb 187.13 23.76 8764.36 24 8852 + + +-- +Groeten, + +Joost Kraaijeveld +Askesis B.V. +Molukkenstraat 14 +6524NB Nijmegen +tel: 024-3888063 / 06-51855277 +fax: 024-3608416 +e-mail: J.Kraaijeveld@Askesis.nl +web: www.askesis.nl + + + +From pgsql-performance-owner@postgresql.org Sun Nov 6 12:31:23 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id EAFF4D8ED6 + for ; + Sun, 6 Nov 2005 12:31:21 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 65729-10 + for ; + Sun, 6 Nov 2005 16:31:20 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 454B6D79D9 + for ; + Sun, 6 Nov 2005 12:31:19 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA6GVI2Q025137; + Sun, 6 Nov 2005 11:31:18 -0500 (EST) +To: "PostgreSQL" +Cc: pgsql-performance@postgresql.org +Subject: Re: 8.1 iss +In-reply-to: +References: +Comments: In-reply-to "PostgreSQL" + message dated "Sun, 06 Nov 2005 03:55:18 -0600" +Date: Sun, 06 Nov 2005 11:31:18 -0500 +Message-ID: <25136.1131294678@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/99 +X-Sequence-Number: 15356 + +"PostgreSQL" writes: +> This is a pretty good example of the place where 8.1 seems to be quite +> broken. + +That's a bit of a large claim on the basis of one data point. +Did you remember to re-ANALYZE after loading the table into the +new database? + + regards, tom lane + +From pgsql-hackers-owner@postgresql.org Sun Nov 6 13:10:32 2005 +X-Original-To: pgsql-hackers-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 3CB4DDACFE; + Sun, 6 Nov 2005 13:10:27 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 86733-05; Sun, 6 Nov 2005 17:10:25 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from trolak.mydnsbox2.com (ns1.mydnsbox2.com [207.44.142.118]) + by svr1.postgresql.org (Postfix) with ESMTP id 0BECADACE5; + Sun, 6 Nov 2005 13:10:24 -0400 (AST) +Received: from [192.168.1.103] (cpe-024-211-165-134.nc.res.rr.com + [24.211.165.134]) (authenticated (0 bits)) + by trolak.mydnsbox2.com (8.11.6/8.11.6) with ESMTP id jA6GQHE02487; + Sun, 6 Nov 2005 10:26:18 -0600 +Message-ID: <436E38EE.2000708@dunslane.net> +Date: Sun, 06 Nov 2005 12:10:06 -0500 +From: Andrew Dunstan +User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; + rv:1.7.12) Gecko/20050922 Fedora/1.7.12-1.3.1 +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Simon Riggs +Cc: Bruce Momjian , + David Fetter , Tom Lane , + Merlin Moncure , + pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org +Subject: Re: [PERFORM] insert performance for win32 +References: <200511041821.jA4IL7117478@candle.pha.pa.us> + <1131267605.8300.2055.camel@localhost.localdomain> +In-Reply-To: <1131267605.8300.2055.camel@localhost.localdomain> +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.034 required=5 tests=[AWL=0.034] +X-Spam-Score: 0.034 +X-Spam-Level: +X-Archive-Number: 200511/236 +X-Sequence-Number: 75518 + + + +Simon Riggs wrote: + +>On Fri, 2005-11-04 at 13:21 -0500, Bruce Momjian wrote: +> +> +>>David Fetter wrote: +>> +>> +>>>On Fri, Nov 04, 2005 at 01:01:20PM -0500, Tom Lane wrote: +>>> +>>> +>>>>I'm inclined to treat this as an outright bug, not just a minor +>>>>performance issue, because it implies that a sufficiently long psql +>>>>script would probably crash a Windows machine. +>>>> +>>>> +>>>Ouch. In light of this, are we *sure* what we've got a is a candidate +>>>for release? +>>> +>>> +>>Good point. It is something we would fix in a minor release, so it +>>doesn't seem worth doing another RC just for that. +>> +>> +> +>Will this be documented in the release notes? If we put unimplemented +>features in TODO, where do we list things we regard as bugs? +> +> +> +> + +No need, I think. It was patched 2 days ago. + +cheers + +andrew + +From pgsql-performance-owner@postgresql.org Sun Nov 6 13:17:27 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 07467DAB28 + for ; + Sun, 6 Nov 2005 13:17:26 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 87808-07 + for ; + Sun, 6 Nov 2005 17:17:24 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 80F9BDAB21 + for ; + Sun, 6 Nov 2005 13:17:24 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA6HHK9L025426; + Sun, 6 Nov 2005 12:17:22 -0500 (EST) +To: Joost Kraaijeveld +Cc: Pgsql-Performance +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware Raid5 / Debian?? +In-reply-to: <1131283854.15471.4.camel@Panoramix> +References: <1131283854.15471.4.camel@Panoramix> +Comments: In-reply-to Joost Kraaijeveld + message dated "Sun, 06 Nov 2005 14:30:54 +0100" +Date: Sun, 06 Nov 2005 12:17:20 -0500 +Message-ID: <25425.1131297440@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/100 +X-Sequence-Number: 15357 + +Joost Kraaijeveld writes: +> I am experiencing very long update queries and I want to know if it +> reasonable to expect them to perform better. + +Does that table have any triggers that would fire on the update? + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Sun Nov 6 14:09:11 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id BA613DAA7B + for ; + Sun, 6 Nov 2005 14:09:09 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 10794-06 + for ; + Sun, 6 Nov 2005 18:09:07 +0000 (GMT) +X-Greylist: delayed 00:06:40.116157 by SQLgrey- +Received: from pop7-1.us4.outblaze.com (pop7-1.us4.outblaze.com + [208.36.123.44]) + by svr1.postgresql.org (Postfix) with SMTP id D8F3ED6862 + for ; + Sun, 6 Nov 2005 14:09:06 -0400 (AST) +Received: (qmail 7209 invoked from network); 6 Nov 2005 18:02:26 -0000 +Received: from unknown (HELO ?217.122.95.222?) + (iddekingej@lycos.com@217.122.95.222) + by pop7-1.us4.outblaze.com with SMTP; 6 Nov 2005 18:02:25 -0000 +Message-ID: <436E453F.3060606@lycos.com> +Date: Sun, 06 Nov 2005 19:02:39 +0100 +From: Jeroen van Iddekinge +User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc4 (X11/20050929) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Performance problem with pg8.0 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=2.319 required=5 tests=[DNS_FROM_RFC_POST=1.44, + DNS_FROM_RFC_WHOIS=0.879] +X-Spam-Score: 2.319 +X-Spam-Level: ** +X-Archive-Number: 200511/101 +X-Sequence-Number: 15358 + +Hello, + +I have some strange performance problems with quering a table.It has +5282864, rows and contains the following columns : id +,no,id_words,position,senpos and sentence all are integer non null. + +Index on : + * no + * no,id_words + * id_words + * senpos, sentence, "no") + * d=primary key + +"select count(1) from words_in_text" takes 9 seconds to compleet. +The query 'select * from words_in_text' takes a verry long time to +return the first record (more that 2 minutes) why? + +Also the following query behaves strange. +select * from words_in_text where no <100 order by no; + +explain shows that pg is using sequence scan. When i turn of sequence +scan, index scan is used and is faster. I have a 'Explain verbose +analyze' of this query is at the end of the mail. +The number of estimated rows is wrong, so I did 'set statistics 1000' on +column no. After this the estimated number of rows was ok, but pg still +was using seq scan. + +Can anyone explain why pg is using sequence and not index scan? + + +The computer is a dell desktop with 768Mb ram. Database on the same +machine. I have analyze and vacuum all tables. +Database is 8.0. + +Thanks +Jeroen + + + + +With enable_seqscan=true + + {SORT + :startup_cost 138632.19 + :total_cost 139441.07 + :plan_rows 323552 + :plan_width 24 + :targetlist ( + {TARGETENTRY + :resdom + {RESDOM + :resno 1 + :restype 23 + :restypmod -1 + :resname id + :ressortgroupref 0 + :resorigtbl 1677903 + :resorigcol 1 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 1 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 1 + } + } + {TARGETENTRY + :resdom + {RESDOM + :resno 2 + :restype 23 + :restypmod -1 + :resname no + :ressortgroupref 1 + :resorigtbl 1677903 + :resorigcol 2 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 2 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 2 + } + } + {TARGETENTRY + :resdom + {RESDOM + :resno 3 + :restype 23 + :restypmod -1 + :resname id_words + :ressortgroupref 0 + :resorigtbl 1677903 + :resorigcol 3 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 3 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 3 + } + } + {TARGETENTRY + :resdom + {RESDOM + :resno 4 + :restype 23 + :restypmod -1 + :resname position + :ressortgroupref 0 + :resorigtbl 1677903 + :resorigcol 4 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 4 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 4 + } + } + {TARGETENTRY + :resdom + {RESDOM + :resno 5 + :restype 23 + :restypmod -1 + :resname senpos + :ressortgroupref 0 + :resorigtbl 1677903 + :resorigcol 5 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 5 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 5 + } + } + {TARGETENTRY + :resdom + {RESDOM + :resno 6 + :restype 23 + :restypmod -1 + :resname sentence + :ressortgroupref 0 + :resorigtbl 1677903 + :resorigcol 6 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 6 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 6 + } + } + ) + :qual <> + :lefttree + {SEQSCAN + :startup_cost 0.00 + :total_cost 104880.80 + :plan_rows 323552 + :plan_width 24 + :targetlist ( + {TARGETENTRY + :resdom + {RESDOM + :resno 1 + :restype 23 + :restypmod -1 + :resname id + :ressortgroupref 0 + :resorigtbl 1677903 + :resorigcol 1 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 1 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 1 + } + } + {TARGETENTRY + :resdom + {RESDOM + :resno 2 + :restype 23 + :restypmod -1 + :resname no + :ressortgroupref 1 + :resorigtbl 1677903 + :resorigcol 2 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 2 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 2 + } + } + {TARGETENTRY + :resdom + {RESDOM + :resno 3 + :restype 23 + :restypmod -1 + :resname id_words + :ressortgroupref 0 + :resorigtbl 1677903 + :resorigcol 3 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 3 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 3 + } + } + {TARGETENTRY + :resdom + {RESDOM + :resno 4 + :restype 23 + :restypmod -1 + :resname position + :ressortgroupref 0 + :resorigtbl 1677903 + :resorigcol 4 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 4 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 4 + } + } + {TARGETENTRY + :resdom + {RESDOM + :resno 5 + :restype 23 + :restypmod -1 + :resname senpos + :ressortgroupref 0 + :resorigtbl 1677903 + :resorigcol 5 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 5 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 5 + } + } + {TARGETENTRY + :resdom + {RESDOM + :resno 6 + :restype 23 + :restypmod -1 + :resname sentence + :ressortgroupref 0 + :resorigtbl 1677903 + :resorigcol 6 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 6 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 6 + } + } + ) + :qual ( + {OPEXPR + :opno 97 + :opfuncid 66 + :opresulttype 16 + :opretset false + :args ( + {VAR + :varno 1 + :varattno 2 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 2 + } + {CONST + :consttype 23 + :constlen 4 + :constbyval true + :constisnull false + :constvalue 4 [ 100 0 0 0 ] + } + ) + } + ) + :lefttree <> + :righttree <> + :initPlan <> + :extParam (b) + :allParam (b) + :nParamExec 0 + :scanrelid 1 + } + :righttree <> + :initPlan <> + :extParam (b) + :allParam (b) + :nParamExec 0 + :numCols 1 + :sortColIdx 2 + :sortOperators 97 + } + + Sort (cost=138632.19..139441.07 rows=323552 width=24) (actual +time=7677.614..8479.980 rows=194141 loops=1) + Sort Key: "no" + -> Seq Scan on words_in_text (cost=0.00..104880.80 rows=323552 +width=24) (actual time=187.118..5761.991 rows=194141 lo +ops=1) + Filter: ("no" < 100) + Total runtime: 9225.382 ms + + +With enable_seqscan=false + + {INDEXSCAN + :startup_cost 0.00 + :total_cost 606313.33 + :plan_rows 323552 + :plan_width 24 + :targetlist ( + {TARGETENTRY + :resdom + {RESDOM + :resno 1 + :restype 23 + :restypmod -1 + :resname id + :ressortgroupref 0 + :resorigtbl 1677903 + :resorigcol 1 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 1 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 1 + } + } + {TARGETENTRY + :resdom + {RESDOM + :resno 2 + :restype 23 + :restypmod -1 + :resname no + :ressortgroupref 1 + :resorigtbl 1677903 + :resorigcol 2 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 2 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 2 + } + } + {TARGETENTRY + :resdom + {RESDOM + :resno 3 + :restype 23 + :restypmod -1 + :resname id_words + :ressortgroupref 0 + :resorigtbl 1677903 + :resorigcol 3 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 3 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 3 + } + } + {TARGETENTRY + :resdom + {RESDOM + :resno 4 + :restype 23 + :restypmod -1 + :resname position + :ressortgroupref 0 + :resorigtbl 1677903 + :resorigcol 4 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 4 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 4 + } + } + {TARGETENTRY + :resdom + {RESDOM + :resno 5 + :restype 23 + :restypmod -1 + :resname senpos + :ressortgroupref 0 + :resorigtbl 1677903 + :resorigcol 5 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 5 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 5 + } + } + {TARGETENTRY + :resdom + {RESDOM + :resno 6 + :restype 23 + :restypmod -1 + :resname sentence + :ressortgroupref 0 + :resorigtbl 1677903 + :resorigcol 6 + :resjunk false + } + :expr + {VAR + :varno 1 + :varattno 6 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 6 + } + } + ) + :qual <> + :lefttree <> + :righttree <> + :initPlan <> + :extParam (b) + :allParam (b) + :nParamExec 0 + :scanrelid 1 + :indxid (o 1677911) + :indxqual (( + {OPEXPR + :opno 97 + :opfuncid 66 + :opresulttype 16 + :opretset false + :args ( + {VAR + :varno 1 + :varattno 1 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 2 + } + {CONST + :consttype 23 + :constlen 4 + :constbyval true + :constisnull false + :constvalue 4 [ 100 0 0 0 ] + } + ) + } + )) + :indxqualorig (( + {OPEXPR + :opno 97 + :opfuncid 66 + :opresulttype 16 + :opretset false + :args ( + {VAR + :varno 1 + :varattno 2 + :vartype 23 + :vartypmod -1 + :varlevelsup 0 + :varnoold 1 + :varoattno 2 + } + {CONST + :consttype 23 + :constlen 4 + :constbyval true + :constisnull false + :constvalue 4 [ 100 0 0 0 ] + } + ) + } + )) + :indxstrategy ((i 1)) + :indxsubtype ((o 0)) + :indxlossy ((i 0)) + :indxorderdir 1 + } + + Index Scan using ind_words_in_text_1 on words_in_text +(cost=0.00..606313.33 rows=323552 width=24) (actual time=0.208..100 +0.085 rows=194141 loops=1) + Index Cond: ("no" < 100) + Total runtime: 1733.601 ms + + + + +From pgsql-performance-owner@postgresql.org Sun Nov 6 15:24:08 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CD624D79D9 + for ; + Sun, 6 Nov 2005 15:24:06 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 30240-08 + for ; + Sun, 6 Nov 2005 19:24:04 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 8B573D6862 + for ; + Sun, 6 Nov 2005 15:24:05 -0400 (AST) +Received: from stark.xeocode.com (stark.xeocode.com [216.58.44.227]) + by svr2.postgresql.org (Postfix) with ESMTP id E0997F0B7D + for ; + Sun, 6 Nov 2005 19:24:05 +0000 (GMT) +Received: from localhost ([127.0.0.1] helo=stark.xeocode.com) + by stark.xeocode.com with smtp (Exim 3.36 #1 (Debian)) + id 1EYq7U-0003HY-00; Sun, 06 Nov 2005 14:24:00 -0500 +To: "PostgreSQL" +Cc: pgsql-performance@postgresql.org +Subject: Re: 8.1 iss +References: +In-Reply-To: +From: Greg Stark +Organization: The Emacs Conspiracy; member since 1992 +Date: 06 Nov 2005 14:24:00 -0500 +Message-ID: <87pspdfulr.fsf@stark.xeocode.com> +Lines: 36 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.01 required=5 tests=[AWL=0.010] +X-Spam-Score: 0.01 +X-Spam-Level: +X-Archive-Number: 200511/102 +X-Sequence-Number: 15359 + + +"PostgreSQL" writes: + +... +> As I post this, the query is approaching an hour of run time. I've listed +> an explain of the query and my non-default conf parameters below. Please +> advise on anything I should change or try, or on any information I can +> provide that could help diagnose this. +> +> +> GroupAggregate (cost=9899282.83..10285434.26 rows=223858 width=15) +> Filter: (count(*) > 1) +> -> Sort (cost=9899282.83..9994841.31 rows=38223392 width=15) +> Sort Key: v_barcode +> -> Seq Scan on lead (cost=0.00..1950947.92 rows=38223392 width=15) +> +> shared_buffers = 50000 +> work_mem = 16384 +... + +It sounds to me like it's doing a large on-disk sort. Increasing work_mem +should improve the efficiency. If you increase it enough it might even be able +to do it in memory, but probably not. + +The shared_buffers is excessive but if you're using the default 8kB block +sizes then it 400MB of shared pages on a 16GB machine ought not cause +problems. It might still be worth trying lowering this to 10,000 or so. + +Is this a custom build from postgresql.org sources? RPM build? Or is it a BSD +ports or Gentoo build with unusual options? + +Perhaps posting actual vmstat and iostat output might help if someone catches +something you didn't see? + +-- +greg + + +From pgsql-performance-owner@postgresql.org Sun Nov 6 15:33:57 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id EE00DDAE3B + for ; + Sun, 6 Nov 2005 15:33:56 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 32601-08 + for ; + Sun, 6 Nov 2005 19:33:54 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from obelix.askesis.nl (laudanum.demon.nl [82.161.125.16]) + by svr1.postgresql.org (Postfix) with ESMTP id E5DBEDADB1 + for ; + Sun, 6 Nov 2005 15:33:53 -0400 (AST) +Received: obelix.askesis.nl 172.31.0.1 from 172.31.1.8 172.31.1.8 via HTTP + with MS-WebStorage 6.0.6249 +Received: from Panoramix by obelix.askesis.nl; 06 Nov 2005 20:33:53 +0100 +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +From: Joost Kraaijeveld +To: Tom Lane +Cc: Pgsql-Performance +In-Reply-To: <25425.1131297440@sss.pgh.pa.us> +References: <1131283854.15471.4.camel@Panoramix> + <25425.1131297440@sss.pgh.pa.us> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Sun, 06 Nov 2005 20:33:53 +0100 +Message-Id: <1131305633.5882.17.camel@Panoramix> +Mime-Version: 1.0 +X-Mailer: Evolution 2.0.4 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.058 required=5 tests=[AWL=0.057, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.058 +X-Spam-Level: +X-Archive-Number: 200511/103 +X-Sequence-Number: 15360 + +On Sun, 2005-11-06 at 12:17 -0500, Tom Lane wrote: +> Does that table have any triggers that would fire on the update? +Alas, no trigger, constrainst, foreign keys, indixes (have I forgotten +something?) + +All queries are slow. E.g (after vacuum): + +select objectid from prototype.orders + +Explain analyse (with PgAdmin): + +Seq Scan on orders (cost=0.00..58211.79 rows=1104379 width=40) (actual +time=441.971..3252.698 rows=1104379 loops=1) +Total runtime: 5049.467 ms + +Actual execution time: 82163 MS (without getting the data) + + +Groeten, + +Joost Kraaijeveld +Askesis B.V. +Molukkenstraat 14 +6524NB Nijmegen +tel: 024-3888063 / 06-51855277 +fax: 024-3608416 +e-mail: J.Kraaijeveld@Askesis.nl +web: www.askesis.nl + + + +From pgsql-performance-owner@postgresql.org Sun Nov 6 19:25:07 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id AB6F6D941B + for ; + Sun, 6 Nov 2005 19:25:05 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 48631-03 + for ; + Sun, 6 Nov 2005 23:25:02 +0000 (GMT) +X-Greylist: delayed 03:03:45.429703 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 2D130D91EB + for ; + Sun, 6 Nov 2005 19:25:03 -0400 (AST) +Received: from mail.Mi8.com (d01gw01.mi8.com [63.240.6.47]) + by svr2.postgresql.org (Postfix) with ESMTP id 0B935F0B38 + for ; + Sun, 6 Nov 2005 20:21:17 +0000 (GMT) +Received: from 172.16.1.110 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D1)); Sun, 06 Nov 2005 15:19:04 -0500 +X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Sun, 6 Nov 2005 + 15:19:03 -0500 +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Subject: Re: 8.1 iss +Date: Sun, 6 Nov 2005 15:19:02 -0500 +Message-ID: <3E37B936B592014B978C4415F90D662DE11D27@MI8NYCMAIL06.Mi8.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] 8.1 iss +Thread-Index: AcXjCFbdANN2flAsRBmN15Nr+kOPJAABvzyG +From: "Luke Lonergan" +To: gsstark@mit.edu, martin@portant.com +Cc: pgsql-performance@postgresql.org +X-OriginalArrivalTime: 06 Nov 2005 20:19:03.0379 (UTC) + FILETIME=[54A12A30:01C5E30F] +X-WSS-ID: 6F70BAB821G4192815-07-01 +Content-Type: text/plain; + charset=utf-8 +Content-Transfer-Encoding: base64 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/105 +X-Sequence-Number: 15362 + +R3JlZywNCg0KSW5jcmVhc2luZyBtZW1vcnkgYWN0dWFsbHkgc2xvd3MgZG93biB0aGUgY3VycmVu +dCBzb3J0IHBlcmZvcm1hbmNlLg0KDQpXZSdyZSB3b3JraW5nIG9uIGEgZml4IGZvciB0aGlzIG5v +dyBpbiBiaXpncmVzLg0KDQpMdWtlDQotLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLQ0KU2VudCBm +cm9tIG15IEJsYWNrQmVycnkgV2lyZWxlc3MgRGV2aWNlDQoNCg0KLS0tLS1PcmlnaW5hbCBNZXNz +YWdlLS0tLS0NCkZyb206IHBnc3FsLXBlcmZvcm1hbmNlLW93bmVyQHBvc3RncmVzcWwub3JnIDxw +Z3NxbC1wZXJmb3JtYW5jZS1vd25lckBwb3N0Z3Jlc3FsLm9yZz4NClRvOiBQb3N0Z3JlU1FMIDxt +YXJ0aW5AcG9ydGFudC5jb20+DQpDQzogcGdzcWwtcGVyZm9ybWFuY2VAcG9zdGdyZXNxbC5vcmcg +PHBnc3FsLXBlcmZvcm1hbmNlQHBvc3RncmVzcWwub3JnPg0KU2VudDogU3VuIE5vdiAwNiAxNDoy +NDowMCAyMDA1DQpTdWJqZWN0OiBSZTogW1BFUkZPUk1dIDguMSBpc3MNCg0KDQoiUG9zdGdyZVNR +TCIgPG1hcnRpbkBwb3J0YW50LmNvbT4gd3JpdGVzOg0KDQouLi4NCj4gQXMgSSBwb3N0IHRoaXMs +IHRoZSBxdWVyeSBpcyBhcHByb2FjaGluZyBhbiBob3VyIG9mIHJ1biB0aW1lLiAgSSd2ZSBsaXN0 +ZWQgDQo+IGFuIGV4cGxhaW4gb2YgdGhlIHF1ZXJ5IGFuZCBteSBub24tZGVmYXVsdCBjb25mIHBh +cmFtZXRlcnMgYmVsb3cuICBQbGVhc2UgDQo+IGFkdmlzZSBvbiBhbnl0aGluZyBJIHNob3VsZCBj +aGFuZ2Ugb3IgdHJ5LCBvciBvbiBhbnkgaW5mb3JtYXRpb24gSSBjYW4gDQo+IHByb3ZpZGUgdGhh +dCBjb3VsZCBoZWxwIGRpYWdub3NlIHRoaXMuDQo+IA0KPiANCj4gR3JvdXBBZ2dyZWdhdGUgIChj +b3N0PTk4OTkyODIuODMuLjEwMjg1NDM0LjI2IHJvd3M9MjIzODU4IHdpZHRoPTE1KQ0KPiAgIEZp +bHRlcjogKGNvdW50KCopID4gMSkNCj4gICAtPiAgU29ydCAgKGNvc3Q9OTg5OTI4Mi44My4uOTk5 +NDg0MS4zMSByb3dzPTM4MjIzMzkyIHdpZHRoPTE1KQ0KPiAgICAgICAgIFNvcnQgS2V5OiB2X2Jh +cmNvZGUNCj4gICAgICAgICAtPiAgU2VxIFNjYW4gb24gbGVhZCAgKGNvc3Q9MC4wMC4uMTk1MDk0 +Ny45MiByb3dzPTM4MjIzMzkyIHdpZHRoPTE1KQ0KPiANCj4gc2hhcmVkX2J1ZmZlcnMgPSA1MDAw +MA0KPiB3b3JrX21lbSA9IDE2Mzg0DQouLi4NCg0KSXQgc291bmRzIHRvIG1lIGxpa2UgaXQncyBk +b2luZyBhIGxhcmdlIG9uLWRpc2sgc29ydC4gSW5jcmVhc2luZyB3b3JrX21lbQ0Kc2hvdWxkIGlt +cHJvdmUgdGhlIGVmZmljaWVuY3kuIElmIHlvdSBpbmNyZWFzZSBpdCBlbm91Z2ggaXQgbWlnaHQg +ZXZlbiBiZSBhYmxlDQp0byBkbyBpdCBpbiBtZW1vcnksIGJ1dCBwcm9iYWJseSBub3QuDQoNClRo +ZSBzaGFyZWRfYnVmZmVycyBpcyBleGNlc3NpdmUgYnV0IGlmIHlvdSdyZSB1c2luZyB0aGUgZGVm +YXVsdCA4a0IgYmxvY2sNCnNpemVzIHRoZW4gaXQgNDAwTUIgb2Ygc2hhcmVkIHBhZ2VzIG9uIGEg +MTZHQiBtYWNoaW5lIG91Z2h0IG5vdCBjYXVzZQ0KcHJvYmxlbXMuIEl0IG1pZ2h0IHN0aWxsIGJl +IHdvcnRoIHRyeWluZyBsb3dlcmluZyB0aGlzIHRvIDEwLDAwMCBvciBzby4NCg0KSXMgdGhpcyBh +IGN1c3RvbSBidWlsZCBmcm9tIHBvc3RncmVzcWwub3JnIHNvdXJjZXM/IFJQTSBidWlsZD8gT3Ig +aXMgaXQgYSBCU0QNCnBvcnRzIG9yIEdlbnRvbyBidWlsZCB3aXRoIHVudXN1YWwgb3B0aW9ucz8N +Cg0KUGVyaGFwcyBwb3N0aW5nIGFjdHVhbCB2bXN0YXQgYW5kIGlvc3RhdCBvdXRwdXQgbWlnaHQg +aGVscCBpZiBzb21lb25lIGNhdGNoZXMNCnNvbWV0aGluZyB5b3UgZGlkbid0IHNlZT8NCg0KLS0g +DQpncmVnDQoNCg0KLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tKGVuZCBvZiBicm9hZGNhc3Qp +LS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tDQpUSVAgMjogRG9uJ3QgJ2tpbGwgLTknIHRoZSBw +b3N0bWFzdGVyDQoNCg== + + +From pgsql-performance-owner@postgresql.org Sun Nov 6 16:26:20 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A736EDAE1D + for ; + Sun, 6 Nov 2005 16:26:16 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 64127-06 + for ; + Sun, 6 Nov 2005 20:26:13 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 7ECC7DAD6D + for ; + Sun, 6 Nov 2005 16:26:13 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA6KQDt2002504; + Sun, 6 Nov 2005 15:26:13 -0500 (EST) +To: Joost Kraaijeveld +Cc: Pgsql-Performance +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +In-reply-to: <1131305633.5882.17.camel@Panoramix> +References: <1131283854.15471.4.camel@Panoramix> + <25425.1131297440@sss.pgh.pa.us> + <1131305633.5882.17.camel@Panoramix> +Comments: In-reply-to Joost Kraaijeveld + message dated "Sun, 06 Nov 2005 20:33:53 +0100" +Date: Sun, 06 Nov 2005 15:26:13 -0500 +Message-ID: <2503.1131308773@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/104 +X-Sequence-Number: 15361 + +Joost Kraaijeveld writes: +> Explain analyse (with PgAdmin): +> ... +> Total runtime: 5049.467 ms +> Actual execution time: 82163 MS (without getting the data) + +I'm confused --- where's the 82sec figure coming from, exactly? + +We've heard reports of performance issues in PgAdmin with large +result sets ... if you do the same query in psql, what happens? + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Mon Nov 7 00:26:14 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id EC8D3D926C + for ; + Mon, 7 Nov 2005 00:26:13 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 67763-04 + for ; + Mon, 7 Nov 2005 04:26:12 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from obelix.askesis.nl (laudanum.demon.nl [82.161.125.16]) + by svr1.postgresql.org (Postfix) with ESMTP id ACF71D79D9 + for ; + Mon, 7 Nov 2005 00:26:10 -0400 (AST) +Received: obelix.askesis.nl 172.31.0.1 from 172.31.1.8 172.31.1.8 via HTTP + with MS-WebStorage 6.0.6249 +Received: from Panoramix by obelix.askesis.nl; 07 Nov 2005 05:26:07 +0100 +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +From: Joost Kraaijeveld +To: Tom Lane +Cc: Pgsql-Performance +In-Reply-To: <2503.1131308773@sss.pgh.pa.us> +References: <1131283854.15471.4.camel@Panoramix> + <25425.1131297440@sss.pgh.pa.us> <1131305633.5882.17.camel@Panoramix> + <2503.1131308773@sss.pgh.pa.us> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Mon, 07 Nov 2005 05:25:59 +0100 +Message-Id: <1131337559.5877.7.camel@Panoramix> +Mime-Version: 1.0 +X-Mailer: Evolution 2.0.4 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.058 required=5 tests=[AWL=0.057, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.058 +X-Spam-Level: +X-Archive-Number: 200511/106 +X-Sequence-Number: 15363 + +Hi Tom, + +On Sun, 2005-11-06 at 15:26 -0500, Tom Lane wrote: +> I'm confused --- where's the 82sec figure coming from, exactly? +>From actually executing the query. + +>From PgAdmin: + +-- Executing query: +select objectid from prototype.orders + +Total query runtime: 78918 ms. +Data retrieval runtime: 188822 ms. +1104379 rows retrieved. + + +> We've heard reports of performance issues in PgAdmin with large +> result sets ... if you do the same query in psql, what happens? +jkr@Panoramix:~/postgresql$ time psql muntdev -c "select objectid from +prototype.orders" > output.txt + +real 0m5.554s +user 0m1.121s +sys 0m0.470s + + +Now *I* am confused. What does PgAdmin do more than giving the query to +the database? + +(BTW: I have repeated both measurements and the numbers above were all +from the last measurement I did and are about average) + +-- +Groeten, + +Joost Kraaijeveld +Askesis B.V. +Molukkenstraat 14 +6524NB Nijmegen +tel: 024-3888063 / 06-51855277 +fax: 024-3608416 +e-mail: J.Kraaijeveld@Askesis.nl +web: www.askesis.nl + + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 00:37:41 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id C4F38D9DC1 + for ; + Mon, 7 Nov 2005 00:37:40 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 72149-07 + for ; + Mon, 7 Nov 2005 04:37:39 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id A79DAD9D6D + for ; + Mon, 7 Nov 2005 00:37:39 -0400 (AST) +Received: from houston.familyhealth.com.au (houston.au.fhnetwork.com + [203.22.197.21]) + by svr2.postgresql.org (Postfix) with ESMTP id B6E43F0D32 + for ; + Mon, 7 Nov 2005 04:37:38 +0000 (GMT) +Received: from houston.familyhealth.com.au (localhost [127.0.0.1]) + by houston.familyhealth.com.au (Postfix) with ESMTP id A78B425087; + Mon, 7 Nov 2005 12:37:32 +0800 (WST) +Received: from [127.0.0.1] (work-40.internal [192.168.0.40]) + by houston.familyhealth.com.au (Postfix) with ESMTP id 0A4E924FFA; + Mon, 7 Nov 2005 12:37:26 +0800 (WST) +Message-ID: <436EDA0B.8030604@familyhealth.com.au> +Date: Mon, 07 Nov 2005 12:37:31 +0800 +From: Christopher Kings-Lynne +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Joost Kraaijeveld +Cc: Tom Lane , + Pgsql-Performance +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +References: <1131283854.15471.4.camel@Panoramix> + <25425.1131297440@sss.pgh.pa.us> + <1131305633.5882.17.camel@Panoramix> + <2503.1131308773@sss.pgh.pa.us> <1131337559.5877.7.camel@Panoramix> +In-Reply-To: <1131337559.5877.7.camel@Panoramix> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-familyhealth-MailScanner-Information: Please contact the ISP for more + information +X-familyhealth-MailScanner: Found to be clean +X-familyhealth-MailScanner-From: chriskl@familyhealth.com.au +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.035 required=5 tests=[AWL=0.035] +X-Spam-Score: 0.035 +X-Spam-Level: +X-Archive-Number: 200511/107 +X-Sequence-Number: 15364 + +> Now *I* am confused. What does PgAdmin do more than giving the query to +> the database? + +It builds it into the data grid GUI object. + +Chris + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 01:05:10 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8A12AD9BE9 + for ; + Mon, 7 Nov 2005 01:05:05 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 84906-01 + for ; + Mon, 7 Nov 2005 05:05:03 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from obelix.askesis.nl (laudanum.demon.nl [82.161.125.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 6EA9BD8A87 + for ; + Mon, 7 Nov 2005 01:05:03 -0400 (AST) +Received: obelix.askesis.nl 172.31.0.1 from 172.31.1.8 172.31.1.8 via HTTP + with MS-WebStorage 6.0.6249 +Received: from Panoramix by obelix.askesis.nl; 07 Nov 2005 06:05:02 +0100 +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +From: Joost Kraaijeveld +To: Christopher Kings-Lynne +Cc: Tom Lane , + Pgsql-Performance +In-Reply-To: <436EDA0B.8030604@familyhealth.com.au> +References: <1131283854.15471.4.camel@Panoramix> + <25425.1131297440@sss.pgh.pa.us> <1131305633.5882.17.camel@Panoramix> + <2503.1131308773@sss.pgh.pa.us> <1131337559.5877.7.camel@Panoramix> + <436EDA0B.8030604@familyhealth.com.au> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Mon, 07 Nov 2005 06:04:57 +0100 +Message-Id: <1131339897.5877.12.camel@Panoramix> +Mime-Version: 1.0 +X-Mailer: Evolution 2.0.4 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.057 required=5 tests=[AWL=0.056, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.057 +X-Spam-Level: +X-Archive-Number: 200511/108 +X-Sequence-Number: 15365 + +On Mon, 2005-11-07 at 12:37 +0800, Christopher Kings-Lynne wrote: +> > Now *I* am confused. What does PgAdmin do more than giving the query to +> > the database? +> +> It builds it into the data grid GUI object. + +Is that not the difference between the total query runtime and the data +retrieval runtime (see below)? + +-- Executing query: +select objectid from prototype.orders + +Total query runtime: 78918 ms. +Data retrieval runtime: 188822 ms. +1104379 rows retrieved. +-- +Groeten, + +Joost Kraaijeveld +Askesis B.V. +Molukkenstraat 14 +6524NB Nijmegen +tel: 024-3888063 / 06-51855277 +fax: 024-3608416 +e-mail: J.Kraaijeveld@Askesis.nl +web: www.askesis.nl + + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 02:05:26 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5DE91D9D35 + for ; + Mon, 7 Nov 2005 02:05:25 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 00654-08 + for ; + Mon, 7 Nov 2005 06:05:23 +0000 (GMT) +X-Greylist: delayed 00:20:55.775201 by SQLgrey- +Received: from zigo.dhs.org (ua-83-227-204-174.cust.bredbandsbolaget.se + [83.227.204.174]) + by svr1.postgresql.org (Postfix) with ESMTP id 5DC4AD9C94 + for ; + Mon, 7 Nov 2005 02:05:22 -0400 (AST) +Received: from zigo.zigo.dhs.org (zigo.zigo.dhs.org [192.168.0.1]) + by zigo.dhs.org (Postfix) with ESMTP + id 34D588467; Mon, 7 Nov 2005 06:44:23 +0100 (CET) +Date: Mon, 7 Nov 2005 06:44:23 +0100 (CET) +From: Dennis Bjorklund +To: PostgreSQL +Cc: pgsql-performance@postgresql.org +Subject: Re: 8.1 iss +In-Reply-To: +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=ISO-8859-1 +Content-Transfer-Encoding: 8BIT +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.352 required=5 tests=[AWL=-0.127, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.352 +X-Spam-Level: +X-Archive-Number: 200511/111 +X-Sequence-Number: 15368 + +On Sun, 6 Nov 2005, PostgreSQL wrote: + +> SELECT v_barcode, count(v_barcode) FROM lead GROUP BY v_barcode HAVING +> count(*) > 1; +> +> This is a dual Opteron box with 16 Gb memory and a 3ware SATA raid +> runing 64bit SUSE. Something seems badly wrong. +> +> GroupAggregate (cost=9899282.83..10285434.26 rows=223858 width=15) +> Filter: (count(*) > 1) +> -> Sort (cost=9899282.83..9994841.31 rows=38223392 width=15) +> Sort Key: v_barcode +> -> Seq Scan on lead (cost=0.00..1950947.92 rows=38223392 width=15) + +What do the plan look like in 8.0? Since it's so much faster I assume you +get a different plan. + +> shared_buffers = 50000 +> work_mem = 16384 +> maintenance_work_mem = 16384 +> max_fsm_pages = 100000 +> max_fsm_relations = 5000 +> wal_buffers = 32 +> checkpoint_segments = 32 +> effective_cache_size = 50000 +> default_statistics_target = 50 + +The effective_cache_size is way too low, only 390M and you have a machine +with 16G. Try bumping it to 1000000 (which means almost 8G, how nice it +would be to be able to write 8G instead...). It could be set even higher +but it's hard for me to know what else your memory is used for. + +I don't know if this setting will affect this very query, but it should +have a positive effect on a lot of queries. + +work_mem also seems low, but it's hard to suggest a good value on it +without knowing more about how your database is used. + +-- +/Dennis Bj�rklund + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 01:47:07 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id BC1CFD7028 + for ; + Mon, 7 Nov 2005 01:47:06 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 95138-07 + for ; + Mon, 7 Nov 2005 05:47:02 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from obelix.askesis.nl (laudanum.demon.nl [82.161.125.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 6C86CD682C + for ; + Mon, 7 Nov 2005 01:47:01 -0400 (AST) +Received: obelix.askesis.nl 172.31.0.1 from 172.31.1.8 172.31.1.8 via HTTP + with MS-WebStorage 6.0.6249 +Received: from Panoramix by obelix.askesis.nl; 07 Nov 2005 06:47:00 +0100 +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +From: Joost Kraaijeveld +To: Christopher Kings-Lynne +Cc: Tom Lane , + Pgsql-Performance +In-Reply-To: <436EDA0B.8030604@familyhealth.com.au> +References: <1131283854.15471.4.camel@Panoramix> + <25425.1131297440@sss.pgh.pa.us> <1131305633.5882.17.camel@Panoramix> + <2503.1131308773@sss.pgh.pa.us> <1131337559.5877.7.camel@Panoramix> + <436EDA0B.8030604@familyhealth.com.au> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Mon, 07 Nov 2005 06:46:41 +0100 +Message-Id: <1131342401.5877.27.camel@Panoramix> +Mime-Version: 1.0 +X-Mailer: Evolution 2.0.4 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.056 required=5 tests=[AWL=0.055, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.056 +X-Spam-Level: +X-Archive-Number: 200511/109 +X-Sequence-Number: 15366 + +Hi Christopher, + +On Mon, 2005-11-07 at 12:37 +0800, Christopher Kings-Lynne wrote: +> > Now *I* am confused. What does PgAdmin do more than giving the query to +> > the database? +> +> It builds it into the data grid GUI object. +But my initial question was about a query that does not produce data at +all (well, a response from the server saying it is finished). I broke +that query off after several hours. + +I am now running the query from my initial question with psql (now for +>1 hour, in a transaction, fsyn off). + +Some statistics : + +uptime: +06:35:55 up 9:47, 6 users, load average: 7.08, 7.21, 6.08 + +iostat -x -k 1 (this output appears to be representative): + +avg-cpu: %user %nice %sys %iowait %idle + 1.00 0.00 0.50 98.51 0.00 + +Device: sda sdb + +rrqm/s 0.00 0.00 +wrqm/s 14.00 611.00 +r/s 0.00 1.00 +w/s 3.00 201.00 +rsec/s 0.00 32.00 +wsec/s 136.00 6680.00 +rkB/s 0.00 16.00 +wkB/s 68.00 3340.00 +avgrq-sz 45.33 33.23 +avgqu-sz 0.00 145.67 +await 0.67 767.19 +svctm 0.67 4.97 +%util 0.20 100.30 + + +-- +Groeten, + +Joost Kraaijeveld +Askesis B.V. +Molukkenstraat 14 +6524NB Nijmegen +tel: 024-3888063 / 06-51855277 +fax: 024-3608416 +e-mail: J.Kraaijeveld@Askesis.nl +web: www.askesis.nl + + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 04:51:14 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 67D43D8ED6 + for ; + Mon, 7 Nov 2005 04:51:12 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 54321-08 + for ; + Mon, 7 Nov 2005 08:51:10 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from anchor-post-35.mail.demon.net (anchor-post-35.mail.demon.net + [194.217.242.85]) + by svr1.postgresql.org (Postfix) with ESMTP id D6F6AD7C7F + for ; + Mon, 7 Nov 2005 04:51:10 -0400 (AST) +Received: from mailgate.vale-housing.co.uk ([194.217.48.34] + helo=vale-housing.co.uk) + by anchor-post-35.mail.demon.net with esmtp (Exim 4.42) + id 1EZ2cU-000IrS-HE + for pgsql-performance@postgresql.org; Mon, 07 Nov 2005 08:44:50 +0000 +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="US-ASCII" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +Date: Mon, 7 Nov 2005 08:51:10 -0000 +Message-ID: + +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Performance PG 8.0 on dual opteron / 4GB / 3ware +Thread-Index: AcXjU63KSoWzPk+/T8C0seRcqq5kuAAJDwKw +From: "Dave Page" +To: "Joost Kraaijeveld" , + "Tom Lane" +Cc: "Pgsql-Performance" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.074 required=5 tests=[AWL=0.074] +X-Spam-Score: 0.074 +X-Spam-Level: +X-Archive-Number: 200511/114 +X-Sequence-Number: 15371 + +=20 + +> -----Original Message----- +> From: pgsql-performance-owner@postgresql.org=20 +> [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of=20 +> Joost Kraaijeveld +> Sent: 07 November 2005 04:26 +> To: Tom Lane +> Cc: Pgsql-Performance +> Subject: Re: [PERFORM] Performance PG 8.0 on dual opteron /=20 +> 4GB / 3ware +>=20 +> Hi Tom, +>=20 +> On Sun, 2005-11-06 at 15:26 -0500, Tom Lane wrote: +> > I'm confused --- where's the 82sec figure coming from, exactly? +> >From actually executing the query. +>=20 +> >From PgAdmin: +>=20 +> -- Executing query: +> select objectid from prototype.orders +>=20 +> Total query runtime: 78918 ms. +> Data retrieval runtime: 188822 ms. +> 1104379 rows retrieved. +>=20 +>=20 +> > We've heard reports of performance issues in PgAdmin with large +> > result sets ... if you do the same query in psql, what happens? +> jkr@Panoramix:~/postgresql$ time psql muntdev -c "select objectid from +> prototype.orders" > output.txt +>=20 +> real 0m5.554s +> user 0m1.121s +> sys 0m0.470s +>=20 +>=20 +> Now *I* am confused. What does PgAdmin do more than giving=20 +> the query to +> the database? + +Nothing - it just uses libpq's pqexec function. The speed issue in +pgAdmin is rendering the results in the grid which can be slow on some +OS's due to inefficiencies in some grid controls with large data sets. +That's why we give 2 times - the first is the query runtime on the +server, the second is data retrieval and rendering (iirc, it's been a +while). + +Regards, Dave + +From pgsql-performance-owner@postgresql.org Mon Nov 7 05:03:24 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id BFFDCD7C81 + for ; + Mon, 7 Nov 2005 05:03:21 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 55849-08 + for ; + Mon, 7 Nov 2005 09:03:18 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from obelix.askesis.nl (laudanum.demon.nl [82.161.125.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 054ECDA4B0 + for ; + Mon, 7 Nov 2005 05:03:18 -0400 (AST) +Received: obelix.askesis.nl 172.31.0.1 from 172.31.1.8 172.31.1.8 via HTTP + with MS-WebStorage 6.0.6249 +Received: from Panoramix by obelix.askesis.nl; 07 Nov 2005 10:03:18 +0100 +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +From: Joost Kraaijeveld +To: Dave Page +Cc: Tom Lane , + Pgsql-Performance +In-Reply-To: + +References: + +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Mon, 07 Nov 2005 10:02:59 +0100 +Message-Id: <1131354179.5877.59.camel@Panoramix> +Mime-Version: 1.0 +X-Mailer: Evolution 2.0.4 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.056 required=5 tests=[AWL=0.055, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.056 +X-Spam-Level: +X-Archive-Number: 200511/115 +X-Sequence-Number: 15372 + +Hi Dave, + +On Mon, 2005-11-07 at 08:51 +0000, Dave Page wrote: +> > On Sun, 2005-11-06 at 15:26 -0500, Tom Lane wrote: +> > > I'm confused --- where's the 82sec figure coming from, exactly? +> > >From actually executing the query. +> > +> > >From PgAdmin: +> > +> > -- Executing query: +> > select objectid from prototype.orders +> > +> > Total query runtime: 78918 ms. +> > Data retrieval runtime: 188822 ms. +> > 1104379 rows retrieved. +> > +> > +> > > We've heard reports of performance issues in PgAdmin with large +> > > result sets ... if you do the same query in psql, what happens? +> > jkr@Panoramix:~/postgresql$ time psql muntdev -c "select objectid from +> > prototype.orders" > output.txt +> > +> > real 0m5.554s +> > user 0m1.121s +> > sys 0m0.470s +> > +> > +> > Now *I* am confused. What does PgAdmin do more than giving +> > the query to +> > the database? +> +> Nothing - it just uses libpq's pqexec function. The speed issue in +> pgAdmin is rendering the results in the grid which can be slow on some +> OS's due to inefficiencies in some grid controls with large data sets. +> That's why we give 2 times - the first is the query runtime on the +> server, the second is data retrieval and rendering (iirc, it's been a +> while). +That is what I thought, but what could explain the difference in query +runtime (78 seconds versus 5 seconds) ? + +-- +Groeten, + +Joost Kraaijeveld +Askesis B.V. +Molukkenstraat 14 +6524NB Nijmegen +tel: 024-3888063 / 06-51855277 +fax: 024-3608416 +e-mail: J.Kraaijeveld@Askesis.nl +web: www.askesis.nl + + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 05:17:16 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B410DD9B27 + for ; + Mon, 7 Nov 2005 05:17:15 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 66095-05 + for ; + Mon, 7 Nov 2005 09:17:13 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from anchor-post-36.mail.demon.net (anchor-post-36.mail.demon.net + [194.217.242.86]) + by svr1.postgresql.org (Postfix) with ESMTP id 37795D9A01 + for ; + Mon, 7 Nov 2005 05:17:14 -0400 (AST) +Received: from mailgate.vale-housing.co.uk ([194.217.48.34] + helo=vale-housing.co.uk) + by anchor-post-36.mail.demon.net with esmtp (Exim 4.42) + id 1EZ37r-0008Ve-LP + for pgsql-performance@postgresql.org; Mon, 07 Nov 2005 09:17:15 +0000 +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="US-ASCII" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +Date: Mon, 7 Nov 2005 09:17:12 -0000 +Message-ID: + +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Performance PG 8.0 on dual opteron / 4GB / 3ware +Thread-Index: AcXjehnAFphKqwXeTvu+v+9HlnLCIwAAF7jA +From: "Dave Page" +To: "Joost Kraaijeveld" +Cc: "Tom Lane" , + "Pgsql-Performance" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.074 required=5 tests=[AWL=0.074] +X-Spam-Score: 0.074 +X-Spam-Level: +X-Archive-Number: 200511/116 +X-Sequence-Number: 15373 + +=20 + +> -----Original Message----- +> From: Joost Kraaijeveld [mailto:J.Kraaijeveld@Askesis.nl]=20 +> Sent: 07 November 2005 09:03 +> To: Dave Page +> Cc: Tom Lane; Pgsql-Performance +> Subject: RE: [PERFORM] Performance PG 8.0 on dual opteron /=20 +> 4GB / 3ware +>=20 +> > Nothing - it just uses libpq's pqexec function. The speed issue in +> > pgAdmin is rendering the results in the grid which can be=20 +> slow on some +> > OS's due to inefficiencies in some grid controls with large=20 +> data sets. +> > That's why we give 2 times - the first is the query runtime on the +> > server, the second is data retrieval and rendering (iirc,=20 +> it's been a +> > while). +> That is what I thought, but what could explain the difference in query +> runtime (78 seconds versus 5 seconds) ? + +Not in terms of our code - we obviously do a little more than just run +the query, but I can't spot anything in there that should be +non-constant time. + +Don't suppose it's anything as simple as you vacuuming in between is it? + +Regards, Dave + +From pgsql-performance-owner@postgresql.org Mon Nov 7 05:51:35 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6772AD7811 + for ; + Mon, 7 Nov 2005 05:51:34 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 72554-08 + for ; + Mon, 7 Nov 2005 09:51:31 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.metronet.co.uk (mail.metronet.co.uk [213.162.97.75]) + by svr1.postgresql.org (Postfix) with ESMTP id 5AE7AD680C + for ; + Mon, 7 Nov 2005 05:51:31 -0400 (AST) +Received: from mainbox.archonet.com + (84-51-143-99.archon037.adsl.metronet.co.uk [84.51.143.99]) + by smtp.metronet.co.uk (MetroNet Mail) with ESMTP + id E55A7418423; Mon, 7 Nov 2005 09:51:24 +0000 (GMT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by mainbox.archonet.com (Postfix) with ESMTP id 69D5515EDA; + Mon, 7 Nov 2005 09:46:44 +0000 (GMT) +Received: from mainbox.archonet.com ([127.0.0.1]) + by localhost (mainbox [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id 22981-03; Mon, 7 Nov 2005 09:46:39 +0000 (GMT) +Received: from [192.168.1.17] (client17.office.archonet.com [192.168.1.17]) + by mainbox.archonet.com (Postfix) with ESMTP id 0545415ED9; + Mon, 7 Nov 2005 09:46:39 +0000 (GMT) +Message-ID: <436F227E.3060805@archonet.com> +Date: Mon, 07 Nov 2005 09:46:38 +0000 +From: Richard Huxton +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20051013) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Jeroen van Iddekinge +Cc: pgsql-performance@postgresql.org +Subject: Re: Performance problem with pg8.0 +References: <436E453F.3060606@lycos.com> +In-Reply-To: <436E453F.3060606@lycos.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.033 required=5 tests=[AWL=0.033] +X-Spam-Score: 0.033 +X-Spam-Level: +X-Archive-Number: 200511/117 +X-Sequence-Number: 15374 + +Jeroen van Iddekinge wrote: +> Hello, +> +> I have some strange performance problems with quering a table.It has +> 5282864, rows and contains the following columns : id +> ,no,id_words,position,senpos and sentence all are integer non null. +> +> Index on : +> * no +> * no,id_words +> * id_words +> * senpos, sentence, "no") +> * d=primary key +> +> "select count(1) from words_in_text" takes 9 seconds to compleet. + +Because it's reading through the whole table. See mailing list archives +for discussion of why it doesn't just use an index. + +> The query 'select * from words_in_text' takes a verry long time to +> return the first record (more that 2 minutes) why? + +A long time for the first row, hardly any time for the others. That's +because it assembles all the rows and returns them at the same time. If +you don't want all the rows at once use a cursor. + +> Also the following query behaves strange. +> select * from words_in_text where no <100 order by no; +> explain shows that pg is using sequence scan. When i turn of sequence +> scan, index scan is used and is faster. I have a 'Explain verbose +> analyze' of this query is at the end of the mail. + +It's just the "explain analyze" that's needed - the "verbose" gives far +more detail than you'll want at this stage. + +> The number of estimated rows is wrong, so I did 'set statistics 1000' on +> column no. After this the estimated number of rows was ok, but pg still +> was using seq scan. + +I don't see the correct row estimate - it looks like it's getting it +wrong again to me. + +> Can anyone explain why pg is using sequence and not index scan? + +There's one of two reasons: +1. It thinks it's going to fetch more rows than it does. +2. It has the relative costs of a seq-scan vs index accesses wrong. + +Can you try an "EXPLAIN ANALYZE" of + select * from words_in_text where no < 100 AND no >= 0 order by no; +Substitute whatever lower bound is sensible for "no". Let's see if that +gives the system a clue. + +Then, we'll need to look at your other tuning settings. Have you made +any changes to your postgresql.conf settings, in particular those +mentioned here: + http://www.powerpostgresql.com/PerfList + +-- + Richard Huxton + Archonet Ltd + +From pgsql-performance-owner@postgresql.org Mon Nov 7 07:07:24 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B3EAED6807 + for ; + Mon, 7 Nov 2005 07:07:22 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 02662-08 + for ; + Mon, 7 Nov 2005 11:07:19 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mx2.surnet.cl (mx2.surnet.cl [216.155.73.181]) + by svr1.postgresql.org (Postfix) with ESMTP id 6F176D7C81 + for ; + Mon, 7 Nov 2005 07:07:19 -0400 (AST) +Received: from unknown (HELO cluster.surnet.cl) ([216.155.73.165]) + by mx2.surnet.cl with ESMTP; 07 Nov 2005 08:06:30 -0300 +X-IronPort-AV: i="3.97,299,1125892800"; + d="scan'208"; a="23875065:sNHT57897578" +Received: from alvh.no-ip.org (216.155.78.23) by cluster.surnet.cl (7.0.043) + (authenticated as alvherre@surnet.cl) + id 43501597002D8D7D; Mon, 7 Nov 2005 08:07:17 -0300 +Received: by alvh.no-ip.org (Postfix, from userid 1000) + id 174F5C2D450; Mon, 7 Nov 2005 08:07:20 -0300 (CLST) +Date: Mon, 7 Nov 2005 08:07:20 -0300 +From: Alvaro Herrera +To: "Christian Paul B. Cosinas" +Cc: pgsql-performance@postgresql.org +Subject: Re: Temporary Table +Message-ID: <20051107110719.GA7012@surnet.cl> +Mail-Followup-To: "Christian Paul B. Cosinas" , + pgsql-performance@postgresql.org +References: <004101c5e3b0$ee534130$1e21100a@ghwk02002147> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <004101c5e3b0$ee534130$1e21100a@ghwk02002147> +User-Agent: Mutt/1.5.10i +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=2.006 required=5 tests=[AWL=-0.240, + DNS_FROM_RFC_ABUSE=0.479, DNS_FROM_RFC_POST=1.44, + RCVD_IN_NJABL_PROXY=0.327] +X-Spam-Score: 2.006 +X-Spam-Level: ** +X-Archive-Number: 200511/118 +X-Sequence-Number: 15375 + +Christian Paul B. Cosinas wrote: +> Does Creating Temporary table in a function and NOT dropping them affects +> the performance of the database? + +The system will drop it automatically, so it shouldn't affect. + +What _could_ be affecting you if you execute that function a lot, is +accumulated bloat in pg_class, pg_attribute, or other system catalogs. +You may want to make sure these are vacuumed often. + +-- +Alvaro Herrera http://www.CommandPrompt.com/ +PostgreSQL Replication, Consulting, Custom Development, 24x7 support + +From pgsql-performance-owner@postgresql.org Mon Nov 7 10:47:52 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A49AADA65B + for ; + Mon, 7 Nov 2005 10:47:50 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 08742-08 + for ; + Mon, 7 Nov 2005 14:47:46 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.198]) + by svr1.postgresql.org (Postfix) with ESMTP id 4A306DA54F + for ; + Mon, 7 Nov 2005 10:47:48 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id 57so316225wri + for ; + Mon, 07 Nov 2005 06:47:53 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=RHSjVWE6Hhmfs5ZNrAL+7gBAbThugSbQXnGiQ+sdLOugeLSz50n13l9JKF++PYco41bPfVTJcocjgnqjqbwpQgRq//2TwHc+BxwY5Jt1B+ckTIYyyb21QmG1bhJljeGPS09NcCNOB1AnIlsleQ80Zye1U0tHrDd7wZe/R6A6Y3g= +Received: by 10.54.117.1 with SMTP id p1mr2002458wrc; + Mon, 07 Nov 2005 06:47:53 -0800 (PST) +Received: by 10.54.83.19 with HTTP; Mon, 7 Nov 2005 06:47:53 -0800 (PST) +Message-ID: <33c6269f0511070647tc648d09p32f9368e8e775e6c@mail.gmail.com> +Date: Mon, 7 Nov 2005 09:47:53 -0500 +From: Alex Turner +To: Joost Kraaijeveld +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware Raid5 / Debian?? +Cc: Pgsql-Performance +In-Reply-To: <1131283854.15471.4.camel@Panoramix> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <1131283854.15471.4.camel@Panoramix> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.092 required=5 tests=[AWL=0.092] +X-Spam-Score: 0.092 +X-Spam-Level: +X-Archive-Number: 200511/119 +X-Sequence-Number: 15376 + +Where are the pg_xlog and data directories with respect to each other? + From this IOStat it looks like they might be on the same partition, +which is not ideal, and actualy surprising that throughput is this +good. You need to seperate pg_xlog and data directories to get any +kind of reasonable performance. Also don't use RAID 5 - RAID 5 bites, +no really - it bites. Use multiple RAID 1s, or RAID 10s, you will get +better performance. 50MB/70MB is about the same as you get from a +single disk or a RAID 1. + +We use 2x9506S8MI controlers, and have maintained excellent +performance with 2xRAID 10 and 2xRAID 1. Make sure you get the +firmware update if you have these controllers though. + +Alex Turner +NetEconomist + +On 11/6/05, Joost Kraaijeveld wrote: +> Hi, +> +> I am experiencing very long update queries and I want to know if it +> reasonable to expect them to perform better. +> +> The query below is running for more than 1.5 hours (5500 seconds) now, +> while the rest of the system does nothing (I don't even type or move a +> mouse...). +> +> - Is that to be expected? +> - Is 180-200 tps with ~ 9000 KB (see output iostat below) not low, given +> the fact that fsync is off? (Note: with bonnie++ I get write +> performance > 50 MB/sec and read performace > 70 MB/sec with > 2000 +> read/write ops /sec? +> - Does anyone else have any experience with the 3Ware RAID controller +> (which is my suspect)? +> - Any good idea how to determine the real botleneck if this is not the +> performance I can expect? +> +> My hard- and software: +> +> - PostgreSQL 8.0.3 +> - Debian 3.1 (Sarge) AMD64 +> - Dual Opteron +> - 4GB RAM +> - 3ware Raid5 with 5 disks +> +> Pieces of my postgresql.conf (All other is default): +> shared_buffers =3D 7500 +> work_mem =3D 260096 +> fsync=3Dfalse +> effective_cache_size =3D 32768 +> +> +> +> The query with explain (amount and orderbedrag_valuta are float8, +> ordernummer and ordernumber int4): +> +> explain update prototype.orders set amount =3D +> odbc.orders.orderbedrag_valuta from odbc.orders where ordernumber =3D +> odbc.orders.ordernummer; +> QUERY PLAN +> -------------------------------------------------------------------------= +---- +> Hash Join (cost=3D50994.74..230038.17 rows=3D1104379 width=3D466) +> Hash Cond: ("outer".ordernumber =3D "inner".ordernummer) +> -> Seq Scan on orders (cost=3D0.00..105360.68 rows=3D3991868 width= +=3D455) +> -> Hash (cost=3D48233.79..48233.79 rows=3D1104379 width=3D15) +> -> Seq Scan on orders (cost=3D0.00..48233.79 rows=3D1104379 +> width=3D15) +> +> +> Sample output from iostat during query (about avarage): +> Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn +> hdc 0.00 0.00 0.00 0 0 +> sda 0.00 0.00 0.00 0 0 +> sdb 187.13 23.76 8764.36 24 8852 +> +> +> -- +> Groeten, +> +> Joost Kraaijeveld +> Askesis B.V. +> Molukkenstraat 14 +> 6524NB Nijmegen +> tel: 024-3888063 / 06-51855277 +> fax: 024-3608416 +> e-mail: J.Kraaijeveld@Askesis.nl +> web: www.askesis.nl +> +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 1: if posting/reading through Usenet, please send an appropriate +> subscribe-nomail command to majordomo@postgresql.org so that your +> message can get through to the mailing list cleanly +> + +From pgsql-performance-owner@postgresql.org Mon Nov 7 03:31:12 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id DED92D682F + for ; + Mon, 7 Nov 2005 03:31:10 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 32618-01 + for ; + Mon, 7 Nov 2005 07:31:07 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mailer.eglobalreach.net (mail.heliustech.net [202.124.128.22]) + by svr1.postgresql.org (Postfix) with ESMTP id 2FDE0D680C + for ; + Mon, 7 Nov 2005 03:31:06 -0400 (AST) +Received: from ghwk02002147 (localhost [127.0.0.1] (may be forged)) + by mailer.eglobalreach.net (8.11.6p2/) with ESMTP id jA77UN304246 + for ; Mon, 7 Nov 2005 15:30:23 +0800 +From: "Christian Paul B. Cosinas" +To: +Subject: FW: Used Memory +Date: Mon, 7 Nov 2005 15:34:41 -0000 +Message-ID: <004001c5e3b0$c5f368a0$1e21100a@ghwk02002147> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +X-Mailer: Microsoft Office Outlook 11 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1506 +Thread-Index: AcXYSRQEEzZVhwc+RZSn0P4xxglPcQAA3w8wAtkKxYA= +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.717 required=5 tests=[AWL=-0.875, + DATE_IN_FUTURE_06_12=1.498, URIBL_SBL=1.094] +X-Spam-Score: 1.717 +X-Spam-Level: * +X-Archive-Number: 200511/112 +X-Sequence-Number: 15369 + +Here are the configuration of our database server: + port = 5432 + max_connections = 300 + superuser_reserved_connections = 10 + authentication_timeout = 60 + shared_buffers = 48000 + sort_mem = 32168 + sync = false + +Do you think this is enough? Or can you recommend a better configuration for +my server? + +The server is also running PHP and Apache but wer'e not using it +extensively. For development purpose only. + +The database slow down is occurring most of the time (when the memory free +is low) I don't think it has something to do with vacuum. We only have a +full server vacuum once a day. + + +-----Original Message----- +From: Mark Kirkwood [mailto:markir@paradise.net.nz] +Sent: Monday, October 24, 2005 3:14 AM +To: Christian Paul B. Cosinas +Cc: pgsql-performance@postgresql.org +Subject: Re: [PERFORM] Used Memory +> +> +> I just noticed that as long as the free memory in the first row (which +> is 55036 as of now) became low, the slower is the response of the +> database server. +> + +Also, how about posting your postgresql.conf (or just the non-default +parameters) to this list? + + + +Some other stuff that could be relevant: + +- Is the machine just a database server, or does it run (say) Apache + Php? +- When the slowdown is noticed, does this coincide with certain activities - +e.g, backup , daily maintenance, data load(!) etc. + + +regards + +Mark + +> +> I choose Polesoft Lockspam to fight spam, and you? +> http://www.polesoft.com/refer.html + +Nope, not me either. + + +I choose Polesoft Lockspam to fight spam, and you? +http://www.polesoft.com/refer.html + + + +I choose Polesoft Lockspam to fight spam, and you? +http://www.polesoft.com/refer.html + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 03:31:35 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id C7995D7AF6 + for ; + Mon, 7 Nov 2005 03:31:32 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 22918-08 + for ; + Mon, 7 Nov 2005 07:31:30 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mailer.eglobalreach.net (mail.heliustech.net [202.124.128.22]) + by svr1.postgresql.org (Postfix) with ESMTP id B9E61D7028 + for ; + Mon, 7 Nov 2005 03:31:30 -0400 (AST) +Received: from ghwk02002147 (localhost [127.0.0.1] (may be forged)) + by mailer.eglobalreach.net (8.11.6p2/) with ESMTP id jA77VUm20602 + for ; Mon, 7 Nov 2005 15:31:30 +0800 +From: "Christian Paul B. Cosinas" +To: +Subject: Temporary Table +Date: Mon, 7 Nov 2005 15:35:49 -0000 +Message-ID: <004101c5e3b0$ee534130$1e21100a@ghwk02002147> +MIME-Version: 1.0 +Content-Type: multipart/alternative; + boundary="----=_NextPart_000_0042_01C5E3B0.EE534130" +X-Mailer: Microsoft Office Outlook 11 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1506 +Thread-Index: AcXWVwx9TKFORE3pS6yM9N43/8G7SwB5T9QAAAEl7OAC3AFREA== +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.748 required=5 tests=[AWL=-0.845, + DATE_IN_FUTURE_06_12=1.498, HTML_MESSAGE=0.001, URIBL_SBL=1.094] +X-Spam-Score: 1.748 +X-Spam-Level: * +X-Archive-Number: 200511/113 +X-Sequence-Number: 15370 + +This is a multi-part message in MIME format. + +------=_NextPart_000_0042_01C5E3B0.EE534130 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit + +Does Creating Temporary table in a function and NOT dropping them affects +the performance of the database? + + + + + +I choose Polesoft Lockspam to fight spam, and you? +http://www.polesoft.com/refer.html + + + +I choose Polesoft Lockspam to fight spam, and you? +http://www.polesoft.com/refer.html + +------=_NextPart_000_0042_01C5E3B0.EE534130 +Content-Type: text/html; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable + + + + + + + + + + + + +
+ +

Does Creating = +Temporary +table in a function and NOT dropping them affects the performance of the +database?

+ +

 

+ +


+
+I choose Polesoft Lockspam to fight spam, and you?
+http://www.polesoft.com/refer.html

+ +
+ +
+
+I choose Polesoft Lockspam to fight spam, and you?
+http://www.polesoft.com/refer.html + + + +------=_NextPart_000_0042_01C5E3B0.EE534130-- + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 13:22:30 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 11C72D6805 + for ; + Mon, 7 Nov 2005 13:22:29 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 71792-09 + for ; + Mon, 7 Nov 2005 17:22:27 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (floppy.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id F2C76DA481 + for ; + Mon, 7 Nov 2005 13:22:26 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id DC32731059; Mon, 7 Nov 2005 18:22:24 +0100 (MET) +From: "PostgreSQL" +X-Newsgroups: pgsql.performance +Subject: Re: 8.1 iss +Date: Mon, 7 Nov 2005 11:22:16 -0600 +Organization: Hub.Org Networking Services +Lines: 36 +Message-ID: +References: +X-Complaints-To: usenet@news.hub.org +X-Priority: 3 +X-MSMail-Priority: Normal +X-Newsreader: Microsoft Outlook Express 6.00.2900.2670 +X-RFC2646: Format=Flowed; Response +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2670 +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/120 +X-Sequence-Number: 15377 + +My most humble apologies to the pg development team (pg_lets?). + +I took Greg Stark's advice and set: + +shared_buffers = 10000 # was 50000 +work_mem = 1048576 # 1Gb - was 16384 + +Also, I noticed that the EXPLAIN ANALYZE consistently thought reads would +take longer than they actually did, so I decreased random_page_cost down to +1 (the server has a SATA Raid at level 10). + +Queries that previously seemed to stall out are still a little slow but +nothing like before. And I'm seeing a more normal balance of CPU and disk +i/o while a query is running instead of the high-cpu-low-disk-read situation +I was seeing before. Concurrency is way up. + +I tried a couple of interim sizes for work_mem and so far, the larger the +better (the server has 16Gb). I'll test a little larger size this evening +and see what it does. Yes, I've read the warning that this is per process. + +Kudos to you Greg, thanks Luke for your comment (though it seems to disagree +with my experience). Also to Dennis, there were not drastic changes in the +plan between 8.0 and 8.1, it was just the actual execution times. + +Martin + +"PostgreSQL" wrote in message +news:dkko49$1v06$1@news.hub.org... +> SELECT v_barcode, count(v_barcode) FROM lead GROUP BY v_barcode HAVING +> count(*) > 1; +> +> This is a pretty good example of the place where 8.1 seems to be quite +> broken. +... + + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 13:48:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 4A39CD78C4 + for ; + Mon, 7 Nov 2005 13:45:40 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 83267-10 + for ; + Mon, 7 Nov 2005 17:45:38 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from moutng.kundenserver.de (moutng.kundenserver.de + [212.227.126.171]) + by svr1.postgresql.org (Postfix) with ESMTP id 9BCA6D72B6 + for ; + Mon, 7 Nov 2005 13:45:37 -0400 (AST) +Received: from p548F3CD6.dip0.t-ipconnect.de [84.143.60.214] + (helo=pse.dyndns.org) + by mrelayeu.kundenserver.de (node=mrelayeu2) with ESMTP (Nemesis), + id 0MKwtQ-1EZB3l2Ckn-0007fY; Mon, 07 Nov 2005 18:45:33 +0100 +Received: from pse1 ([192.168.0.3]) by pse.dyndns.org with esmtp (Exim 4.44) + id 1EZB3j-0002Uf-MT; Mon, 07 Nov 2005 18:45:31 +0100 +Message-ID: <436F92BB.7040807@pse-consulting.de> +Date: Mon, 07 Nov 2005 17:45:31 +0000 +From: Andreas Pflug +User-Agent: Mozilla Thunderbird 1.0 (X11/20041206) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Dave Page +Cc: Joost Kraaijeveld , + Tom Lane , + Pgsql-Performance +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +References: + +In-Reply-To: + +X-Enigmail-Version: 0.89.5.0 +X-Enigmail-Supports: pgp-inline, pgp-mime +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Provags-ID: kundenserver.de abuse@kundenserver.de + login:0ce7ee5c3478b8d72edd8e05ccd40b70 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.125 required=5 tests=[AWL=0.125] +X-Spam-Score: 0.125 +X-Spam-Level: +X-Archive-Number: 200511/121 +X-Sequence-Number: 15378 + +Dave Page wrote: + +>> +>> +>>Now *I* am confused. What does PgAdmin do more than giving +>>the query to +>>the database? +> +> +> Nothing - it just uses libpq's pqexec function. The speed issue in +> pgAdmin is rendering the results in the grid which can be slow on some +> OS's due to inefficiencies in some grid controls with large data sets. +> That's why we give 2 times - the first is the query runtime on the +> server, the second is data retrieval and rendering (iirc, it's been a +> while). + +yrnc. +Query runtime includes data transfer to the client, i.e. until libpq +returns the set, second time is retrieving data from libpq and rendering. + +Regards, + +From pgsql-performance-owner@postgresql.org Mon Nov 7 14:11:09 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5FF85D8E25 + for ; + Mon, 7 Nov 2005 14:07:46 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 94515-01 + for ; + Mon, 7 Nov 2005 18:07:41 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from metux.de (seven.metux.de [193.16.1.1]) + by svr1.postgresql.org (Postfix) with ESMTP id 66A8DD8316 + for ; + Mon, 7 Nov 2005 14:07:40 -0400 (AST) +Received: (from weigelt@localhost) + by metux.de (8.12.10/8.12.10) id jA7I7ck7026690 + for pgsql-performance@postgresql.org; Mon, 7 Nov 2005 19:07:38 +0100 +Date: Mon, 7 Nov 2005 19:07:38 +0100 +From: Enrico Weigelt +To: pgsql-performance@postgresql.org +Subject: Index + mismatching datatypes [WAS: index on custom function; + explain] +Message-ID: <20051107180738.GC15990@nibiru.local> +Reply-To: weigelt@metux.de +Mail-Followup-To: pgsql-performance@postgresql.org +References: <1128352451.312090.37640@g44g2000cwa.googlegroups.com> + <20051006081919.GA17081@zoom.spline.inf.fu-berlin.de> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <20051006081919.GA17081@zoom.spline.inf.fu-berlin.de> +User-Agent: Mutt/1.4.1i +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.004 required=5 tests=[AWL=0.004] +X-Spam-Score: 0.004 +X-Spam-Level: +X-Archive-Number: 200511/122 +X-Sequence-Number: 15379 + +* Yann Michel wrote: + +> TIP 9: In versions below 8.0, the planner will ignore your desire to +> choose an index scan if your joining column's datatypes do not +> match + +I've got a similar problem: I have to match different datatypes, +ie. bigint vs. integer vs. oid. + +Of course I tried to use casted index (aka ON (foo::oid)), but +it didn't work. + +What am I doing wrong ? + + +cu +-- +--------------------------------------------------------------------- + Enrico Weigelt == metux IT service + phone: +49 36207 519931 www: http://www.metux.de/ + fax: +49 36207 519932 email: contact@metux.de +--------------------------------------------------------------------- + Realtime Forex/Stock Exchange trading powered by postgreSQL :)) + http://www.fxignal.net/ +--------------------------------------------------------------------- + +From pgsql-performance-owner@postgresql.org Mon Nov 7 16:42:03 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 7B824D8316 + for ; + Mon, 7 Nov 2005 16:42:02 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 51481-02 + for ; + Mon, 7 Nov 2005 20:42:00 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mailbox.samurai.com (mailbox.samurai.com [205.207.28.82]) + by svr1.postgresql.org (Postfix) with ESMTP id 0168BD6805 + for ; + Mon, 7 Nov 2005 16:42:00 -0400 (AST) +Received: from localhost (mailbox.samurai.com [205.207.28.82]) + by mailbox.samurai.com (Postfix) with ESMTP id 81154239607; + Mon, 7 Nov 2005 15:42:02 -0500 (EST) +Received: from mailbox.samurai.com ([205.207.28.82]) + by localhost (mailbox.samurai.com [205.207.28.82]) (amavisd-new, + port 10024) + with LMTP id 42225-01-9; Mon, 7 Nov 2005 15:42:01 -0500 (EST) +Received: from [192.168.1.104] (d226-86-55.home.cgocable.net [24.226.86.55]) + by mailbox.samurai.com (Postfix) with ESMTP id 12ED2239461; + Mon, 7 Nov 2005 15:42:01 -0500 (EST) +Subject: Re: Index + mismatching datatypes [WAS: index on custom +From: Neil Conway +To: weigelt@metux.de +Cc: pgsql-performance@postgresql.org +In-Reply-To: <20051107180738.GC15990@nibiru.local> +References: <1128352451.312090.37640@g44g2000cwa.googlegroups.com> + <20051006081919.GA17081@zoom.spline.inf.fu-berlin.de> + <20051107180738.GC15990@nibiru.local> +Content-Type: text/plain +Date: Mon, 07 Nov 2005 15:45:57 -0500 +Message-Id: <1131396357.6884.110.camel@localhost.localdomain> +Mime-Version: 1.0 +X-Mailer: Evolution 2.4.1 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at mailbox.samurai.com +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/123 +X-Sequence-Number: 15380 + +On Mon, 2005-07-11 at 19:07 +0100, Enrico Weigelt wrote: +> I've got a similar problem: I have to match different datatypes, +> ie. bigint vs. integer vs. oid. +> +> Of course I tried to use casted index (aka ON (foo::oid)), but +> it didn't work. + +Don't include the cast in the index definition, include it in the query +itself: + + SELECT ... FROM foo WHERE int8col = 5::int8 + +for example. Alternatively, upgrade to 8.0 or better, which doesn't +require this workaround. + +-Neil + + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 17:35:22 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id EE71FDAF2C + for ; + Mon, 7 Nov 2005 17:35:21 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 66450-06 + for ; + Mon, 7 Nov 2005 21:35:19 +0000 (GMT) +X-Greylist: delayed 00:05:02.594679 by SQLgrey- +Received: from nz.telogis.com (unknown [203.98.10.169]) + by svr1.postgresql.org (Postfix) with ESMTP id 47E84DAD86 + for ; + Mon, 7 Nov 2005 17:35:20 -0400 (AST) +Received: from [192.168.3.1] ([192.168.3.1]) + by nz.telogis.com with esmtp; Tue, 08 Nov 2005 10:30:16 +1300 + id 006BD844.436FC769.00003B46 +Message-ID: <436FC767.1010702@telogis.com> +Date: Tue, 08 Nov 2005 10:30:15 +1300 +From: Ralph Mason +User-Agent: Thunderbird 1.4 (Windows/20050908) +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Figuring out which command failed +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/124 +X-Sequence-Number: 15381 + +Hi, + +I have a transaction that has multiple separate command in it (nothing +unusual there). + +However sometimes one of the sql statements will fail and so the whole +transaction fails. + +In some cases I could fix the failing statement if only I knew which one +it was. Can anyone think of any way to get which statement actually +failed from the error message? If the error message gave me the line of +the failure it would be excellent, but it doesn't. Perhaps it would be +easy for me to patch my version of Postgres to do that? + +I realize I could do this with 2 phase commit, but that isn't ready yet! + +Any thoughts or ideas are much appreciated + +Thanks +Ralph + +From pgsql-performance-owner@postgresql.org Mon Nov 7 17:40:15 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id C8AC2D6892 + for ; + Mon, 7 Nov 2005 17:40:14 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 69119-05 + for ; + Mon, 7 Nov 2005 21:40:12 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from nz.telogis.com (unknown [203.98.10.169]) + by svr1.postgresql.org (Postfix) with ESMTP id 770E5D6834 + for ; + Mon, 7 Nov 2005 17:40:13 -0400 (AST) +Received: from [192.168.3.1] ([192.168.3.1]) + by nz.telogis.com with esmtp; Tue, 08 Nov 2005 10:40:08 +1300 + id 006116D6.436FC9BD.00003B66 +Message-ID: <436FC9B1.4000906@telogis.com> +Date: Tue, 08 Nov 2005 10:40:01 +1300 +From: Ralph Mason +User-Agent: Thunderbird 1.4 (Windows/20050908) +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: Temporary Table +References: <004101c5e3b0$ee534130$1e21100a@ghwk02002147> + <20051107110719.GA7012@surnet.cl> +In-Reply-To: <20051107110719.GA7012@surnet.cl> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/125 +X-Sequence-Number: 15382 + +Alvaro Herrera wrote: +> Christian Paul B. Cosinas wrote: +> +>> Does Creating Temporary table in a function and NOT dropping them affects +>> the performance of the database? +>> +> +> The system will drop it automatically, so it shouldn't affect. +> +> What _could_ be affecting you if you execute that function a lot, is +> accumulated bloat in pg_class, pg_attribute, or other system catalogs. +> You may want to make sure these are vacuumed often. +> +> +The answer in my experience is a very loud YES YES YES + +If you use lots of temporary tables you will grow and dirty your system +catalogs, so you need to be vacuuming them regularly also (pg_call, +pg_attribute) Otherwise your db will slow to a crawl after a while. + +Ralph + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 23:01:13 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5F7C2D8055 + for ; + Mon, 7 Nov 2005 23:01:11 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 84192-09 + for ; + Tue, 8 Nov 2005 03:01:04 +0000 (GMT) +X-Greylist: delayed 01:00:45.562753 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id B1811D7C60 + for ; + Mon, 7 Nov 2005 23:01:05 -0400 (AST) +Received: from moonunit2.moonview.localnet (wsip-68-15-5-150.sd.sd.cox.net + [68.15.5.150]) + by svr2.postgresql.org (Postfix) with ESMTP id 02D08F0D2C + for ; + Tue, 8 Nov 2005 02:00:23 +0000 (GMT) +Received: from [192.168.0.3] (moonunit3.moonview.localnet [192.168.0.3]) + by moonunit2.moonview.localnet (8.13.1/8.13.1) with ESMTP id + jA827ZxT023899 + for ; Mon, 7 Nov 2005 18:07:36 -0800 +Message-ID: <4370062B.4050202@modgraph-usa.com> +Date: Mon, 07 Nov 2005 17:58:03 -0800 +From: "Craig A. James" +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20050716) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Expensive function and the optimizer +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.025 required=5 tests=[AWL=0.025] +X-Spam-Score: 0.025 +X-Spam-Level: +X-Archive-Number: 200511/134 +X-Sequence-Number: 15391 + +I have a function, call it "myfunc()", that is REALLY expensive computationally. Think of it like, "If you call this function, it's going to telephone the Microsoft Help line and wait in their support queue to get the answer." Ok, it's not that bad, but it's so bad that the optimizer should ALWAYS consider it last, no matter what. (Realistically, the function takes 1-2 msec average, so applying it to 40K rows takes 40-80 seconds. It's a graph-theory algorithm, known to be NP-complete.) + +Is there some way to explain this cost to the optimizer in a permanent way, like when the function is installed? Here's what I get with one critical query (somewhat paraphrased for simplicity): + + explain analyze + select A.ID + from A join B ON (A.ID = B.ID) + where A.row_num >= 0 and A.row_num <= 43477 + and B.ID = 52 + and myfunc(A.FOO, 'FooBar') order by row_num; + + QUERY PLAN + ---------------------------------------------------------------------------------- + Nested Loop (cost=0.00..72590.13 rows=122 width=8) + -> Index Scan using i_a_row_num on a (cost=0.00..10691.35 rows=12222 width=8) + Index Cond: ((row_num >= 0) AND (row_num <= 43477)) + Filter: myfunc((foo)::text, 'FooBar'::text) + -> Index Scan using i_b_id on b (cost=0.00..5.05 rows=1 width=4) + Index Cond: ("outer".id = b.id) + Filter: (id = 52) + Total runtime: 62592.631 ms + (8 rows) + +Notice the "Filter: myfunc(...)" that comes in the first loop. This means it's applying myfunc() to 43477 rows in this example. The second index scan would cut this number down from 43477 rows to about 20 rows, making the query time drop from 62 seconds down to a fraction of a second. + +Is there any way to give Postgres this information? + +The only way I've thought of is something like this: + + select X.id from + (select A.id, A.foo, A.row_num + from A join B ON (A.id = B.id) + where A.row_num >= 0 and A.row_num <= 43477 + and B.id = 52) as X + where myfunc(X.foo, 'FooBar') order by X.row_num; + +I can do this, but it means carefully hand-crafting each query rather than writing a more natural query. + +Thanks, +Craig + +From pgsql-performance-owner@postgresql.org Mon Nov 7 22:10:43 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id EF067DAD68 + for ; + Mon, 7 Nov 2005 22:10:42 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 68577-09 + for ; + Tue, 8 Nov 2005 02:10:39 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from hosting.commandprompt.com (128.commandprompt.com + [207.173.200.128]) + by svr1.postgresql.org (Postfix) with ESMTP id 6DCF5DAA49 + for ; + Mon, 7 Nov 2005 22:10:41 -0400 (AST) +Received: from [192.168.1.105] (clbb-248.saw.net [64.146.135.248]) + (authenticated bits=0) + by hosting.commandprompt.com (8.13.4/8.13.4) with ESMTP id + jA82680h014921; Mon, 7 Nov 2005 18:06:13 -0800 +Message-ID: <4370091E.8060700@commandprompt.com> +Date: Mon, 07 Nov 2005 18:10:38 -0800 +From: "Joshua D. Drake" +Organization: Command Prompt, Inc. +User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: "Christian Paul B. Cosinas" +Cc: "'Alvaro Nunes Melo'" , + pgsql-performance@postgresql.org +Subject: Re: Temporary Table +References: <008301c5e44c$70eee900$1e21100a@ghwk02002147> +In-Reply-To: <008301c5e44c$70eee900$1e21100a@ghwk02002147> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Greylist: Sender succeded SMTP AUTH authentication, not delayed by + milter-greylist-1.6 (hosting.commandprompt.com [192.168.1.101]); + Mon, 07 Nov 2005 18:06:13 -0800 (PST) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.567 required=5 tests=[AWL=-0.527, URIBL_SBL=1.094] +X-Spam-Score: 0.567 +X-Spam-Level: +X-Archive-Number: 200511/128 +X-Sequence-Number: 15385 + +Christian Paul B. Cosinas wrote: +> I try to run this command in my linux server. +> VACUUM FULL pg_class; +> VACUUM FULL pg_attribute; +> VACUUM FULL pg_depend; +> +> But it give me the following error: +> -bash: VACUUM: command not found + +That needs to be run from psql ... + +> +> +> +> +> +> I choose Polesoft Lockspam to fight spam, and you? +> http://www.polesoft.com/refer.html +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 4: Have you searched our list archives? +> +> http://archives.postgresql.org + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 22:13:53 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 7074DD72B6 + for ; + Mon, 7 Nov 2005 22:13:52 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 71052-10 + for ; + Tue, 8 Nov 2005 02:13:49 +0000 (GMT) +X-Greylist: delayed 21:36:12.623567 by SQLgrey- +Received: from houston.familyhealth.com.au (houston.au.fhnetwork.com + [203.22.197.21]) + by svr1.postgresql.org (Postfix) with ESMTP id DC879D6E2C + for ; + Mon, 7 Nov 2005 22:13:50 -0400 (AST) +Received: from houston.familyhealth.com.au (localhost [127.0.0.1]) + by houston.familyhealth.com.au (Postfix) with ESMTP id 5F59525070; + Tue, 8 Nov 2005 10:13:52 +0800 (WST) +Received: from [127.0.0.1] (work-40.internal [192.168.0.40]) + by houston.familyhealth.com.au (Postfix) with ESMTP id 5E70824FFA; + Tue, 8 Nov 2005 10:13:51 +0800 (WST) +Message-ID: <43700A15.9000506@familyhealth.com.au> +Date: Tue, 08 Nov 2005 10:14:45 +0800 +From: Christopher Kings-Lynne +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: "Christian Paul B. Cosinas" +Cc: 'Alvaro Nunes Melo' , + pgsql-performance@postgresql.org +Subject: Re: Temporary Table +References: <008301c5e44c$70eee900$1e21100a@ghwk02002147> +In-Reply-To: <008301c5e44c$70eee900$1e21100a@ghwk02002147> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-familyhealth-MailScanner-Information: Please contact the ISP for more + information +X-familyhealth-MailScanner: Found to be clean +X-familyhealth-MailScanner-From: chriskl@familyhealth.com.au +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.581 required=5 tests=[AWL=-0.513, URIBL_SBL=1.094] +X-Spam-Score: 0.581 +X-Spam-Level: +X-Archive-Number: 200511/129 +X-Sequence-Number: 15386 + +Ummm...they're SQL commands. Run them in PostgreSQL, not on the unix +command line... + +Christian Paul B. Cosinas wrote: +> I try to run this command in my linux server. +> VACUUM FULL pg_class; +> VACUUM FULL pg_attribute; +> VACUUM FULL pg_depend; +> +> But it give me the following error: +> -bash: VACUUM: command not found +> +> +> +> +> +> I choose Polesoft Lockspam to fight spam, and you? +> http://www.polesoft.com/refer.html +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 4: Have you searched our list archives? +> +> http://archives.postgresql.org + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 22:14:16 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id BDCD0DACE8 + for ; + Mon, 7 Nov 2005 22:14:14 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 70702-07 + for ; + Tue, 8 Nov 2005 02:14:11 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from houston.familyhealth.com.au (houston.au.fhnetwork.com + [203.22.197.21]) + by svr1.postgresql.org (Postfix) with ESMTP id F0EB6D9A17 + for ; + Mon, 7 Nov 2005 22:14:12 -0400 (AST) +Received: from houston.familyhealth.com.au (localhost [127.0.0.1]) + by houston.familyhealth.com.au (Postfix) with ESMTP id 6344E25092; + Tue, 8 Nov 2005 10:14:16 +0800 (WST) +Received: from [127.0.0.1] (work-40.internal [192.168.0.40]) + by houston.familyhealth.com.au (Postfix) with ESMTP id 80DBB25091; + Tue, 8 Nov 2005 10:14:15 +0800 (WST) +Message-ID: <43700A2E.8060008@familyhealth.com.au> +Date: Tue, 08 Nov 2005 10:15:10 +0800 +From: Christopher Kings-Lynne +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: "Christian Paul B. Cosinas" +Cc: 'Alvaro Nunes Melo' , + pgsql-performance@postgresql.org +Subject: Re: Temporary Table +References: <008201c5e44b$c0cdf390$1e21100a@ghwk02002147> +In-Reply-To: <008201c5e44b$c0cdf390$1e21100a@ghwk02002147> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-familyhealth-MailScanner-Information: Please contact the ISP for more + information +X-familyhealth-MailScanner: Found to be clean +X-familyhealth-MailScanner-From: chriskl@familyhealth.com.au +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.035 required=5 tests=[AWL=0.035] +X-Spam-Score: 0.035 +X-Spam-Level: +X-Archive-Number: 200511/130 +X-Sequence-Number: 15387 + +> In what directory in my linux server will I find these 3 tables? + +Directory? They're tables in your database... + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 22:29:39 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 1F78ED9A17 + for ; + Mon, 7 Nov 2005 22:29:38 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 81356-02 + for ; + Tue, 8 Nov 2005 02:29:30 +0000 (GMT) +X-Greylist: delayed 00:06:38.782794 by SQLgrey- +Received: from smtp111.sbc.mail.mud.yahoo.com (smtp111.sbc.mail.mud.yahoo.com + [68.142.198.210]) + by svr1.postgresql.org (Postfix) with SMTP id 484D8D6892 + for ; + Mon, 7 Nov 2005 22:29:32 -0400 (AST) +Received: (qmail 99335 invoked from network); 8 Nov 2005 02:22:55 -0000 +Received: from unknown (HELO discord.dyndns.org) + (jeffroe996@sbcglobal.net@69.227.55.89 with plain) + by smtp111.sbc.mail.mud.yahoo.com with SMTP; 8 Nov 2005 02:22:55 -0000 +Received: from localhost (localhost.localdomain [127.0.0.1]) + by discord.dyndns.org (8.13.4/8.13.4) with ESMTP id jA82MsUC018935; + Mon, 7 Nov 2005 18:22:54 -0800 +Date: Mon, 7 Nov 2005 18:22:54 -0800 (PST) +From: Jeff Frost +X-X-Sender: jeff@discord.dyndns.org +To: "Christian Paul B. Cosinas" +Cc: "'Joshua D. Drake'" , + "'Alvaro Nunes Melo'" , + pgsql-performance@postgresql.org +Subject: Re: Temporary Table +In-Reply-To: <008401c5e44e$42600c20$1e21100a@ghwk02002147> +Message-ID: +References: <008401c5e44e$42600c20$1e21100a@ghwk02002147> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.572 required=5 tests=[AWL=-0.522, URIBL_SBL=1.094] +X-Spam-Score: 0.572 +X-Spam-Level: +X-Archive-Number: 200511/133 +X-Sequence-Number: 15390 + +You can use the vacuumdb external command. Here's an example: + +vacuumdb --full --analyze --table mytablename mydbname + + + +On Tue, 8 Nov 2005, Christian Paul B. Cosinas wrote: + +> But How Can I put this in the Cron of my Linux Server? +> I really don't have an idea :) +> What I want to do is to loop around all the databases in my server and +> execute the vacuum of these 3 tables in each tables. +> +> -----Original Message----- +> From: Joshua D. Drake [mailto:jd@commandprompt.com] +> Sent: Tuesday, November 08, 2005 2:11 AM +> To: Christian Paul B. Cosinas +> Cc: 'Alvaro Nunes Melo'; pgsql-performance@postgresql.org +> Subject: Re: [PERFORM] Temporary Table +> +> Christian Paul B. Cosinas wrote: +>> I try to run this command in my linux server. +>> VACUUM FULL pg_class; +>> VACUUM FULL pg_attribute; +>> VACUUM FULL pg_depend; +>> +>> But it give me the following error: +>> -bash: VACUUM: command not found +> +> That needs to be run from psql ... +> +>> +>> +>> +>> +>> +>> I choose Polesoft Lockspam to fight spam, and you? +>> http://www.polesoft.com/refer.html +>> +>> +>> ---------------------------(end of +>> broadcast)--------------------------- +>> TIP 4: Have you searched our list archives? +>> +>> http://archives.postgresql.org +> +> +> I choose Polesoft Lockspam to fight spam, and you? +> http://www.polesoft.com/refer.html +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 2: Don't 'kill -9' the postmaster +> + +-- +Jeff Frost, Owner +Frost Consulting, LLC http://www.frostconsultingllc.com/ +Phone: 650-780-7908 FAX: 650-649-1954 + +From pgsql-performance-owner@postgresql.org Mon Nov 7 22:23:28 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 72CF9D72B6 + for ; + Mon, 7 Nov 2005 22:23:27 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 78079-07 + for ; + Tue, 8 Nov 2005 02:23:23 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from houston.familyhealth.com.au (houston.au.fhnetwork.com + [203.22.197.21]) + by svr1.postgresql.org (Postfix) with ESMTP id AF2ECD6E2C + for ; + Mon, 7 Nov 2005 22:23:25 -0400 (AST) +Received: from houston.familyhealth.com.au (localhost [127.0.0.1]) + by houston.familyhealth.com.au (Postfix) with ESMTP id 8AADF25094; + Tue, 8 Nov 2005 10:23:29 +0800 (WST) +Received: from [127.0.0.1] (work-40.internal [192.168.0.40]) + by houston.familyhealth.com.au (Postfix) with ESMTP id DE48025087; + Tue, 8 Nov 2005 10:23:25 +0800 (WST) +Message-ID: <43700C54.2010701@familyhealth.com.au> +Date: Tue, 08 Nov 2005 10:24:20 +0800 +From: Christopher Kings-Lynne +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: "Christian Paul B. Cosinas" +Cc: "'Joshua D. Drake'" , + 'Alvaro Nunes Melo' , + pgsql-performance@postgresql.org +Subject: Re: Temporary Table +References: <008401c5e44e$42600c20$1e21100a@ghwk02002147> +In-Reply-To: <008401c5e44e$42600c20$1e21100a@ghwk02002147> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-familyhealth-MailScanner-Information: Please contact the ISP for more + information +X-familyhealth-MailScanner: Found to be clean +X-familyhealth-MailScanner-From: chriskl@familyhealth.com.au +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.583 required=5 tests=[AWL=-0.511, URIBL_SBL=1.094] +X-Spam-Score: 0.583 +X-Spam-Level: +X-Archive-Number: 200511/132 +X-Sequence-Number: 15389 + +Or you could just run the 'vacuumdb' utility... + +Put something like this in cron: + +# Vacuum full local pgsql database +30 * * * * postgres vacuumdb -a -q -z + +You really should read the manual. + +Chris + +Christian Paul B. Cosinas wrote: +> I see. +> +> But How Can I put this in the Cron of my Linux Server? +> I really don't have an idea :) +> What I want to do is to loop around all the databases in my server and +> execute the vacuum of these 3 tables in each tables. +> +> -----Original Message----- +> From: Joshua D. Drake [mailto:jd@commandprompt.com] +> Sent: Tuesday, November 08, 2005 2:11 AM +> To: Christian Paul B. Cosinas +> Cc: 'Alvaro Nunes Melo'; pgsql-performance@postgresql.org +> Subject: Re: [PERFORM] Temporary Table +> +> Christian Paul B. Cosinas wrote: +> +>>I try to run this command in my linux server. +>>VACUUM FULL pg_class; +>>VACUUM FULL pg_attribute; +>>VACUUM FULL pg_depend; +>> +>>But it give me the following error: +>> -bash: VACUUM: command not found +> +> +> That needs to be run from psql ... +> +> +>> +>> +>> +>> +>>I choose Polesoft Lockspam to fight spam, and you? +>>http://www.polesoft.com/refer.html +>> +>> +>>---------------------------(end of +>>broadcast)--------------------------- +>>TIP 4: Have you searched our list archives? +>> +>> http://archives.postgresql.org +> +> +> +> I choose Polesoft Lockspam to fight spam, and you? +> http://www.polesoft.com/refer.html +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 2: Don't 'kill -9' the postmaster + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 23:02:48 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 86F79DB127 + for ; + Mon, 7 Nov 2005 23:02:39 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 91812-07 + for ; + Tue, 8 Nov 2005 03:02:26 +0000 (GMT) +X-Greylist: delayed 00:26:46.548572 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id F24B6DB1D9 + for ; + Mon, 7 Nov 2005 23:01:55 -0400 (AST) +Received: from mail1.catalyst.net.nz (godel.catalyst.net.nz [202.78.240.40]) + by svr2.postgresql.org (Postfix) with ESMTP id 7B336F0DE4 + for ; + Tue, 8 Nov 2005 02:35:33 +0000 (GMT) +Received: from 218-101-8-114.xtreme.net.nz ([218.101.8.114] + helo=ubu.mcmillan.net.nz) by mail1.catalyst.net.nz with esmtpsa + (TLS-1.0:DHE_RSA_AES_256_CBC_SHA:32) (Exim 4.50) + id 1EZJKS-00037g-VN; Tue, 08 Nov 2005 15:35:21 +1300 +Received: by ubu.mcmillan.net.nz (Postfix, from userid 1000) + id 96B396F0A0A; Tue, 8 Nov 2005 15:35:20 +1300 (NZDT) +Subject: Re: Temporary Table +From: Andrew McMillan +To: "Christian Paul B. Cosinas" +Cc: "'Joshua D. Drake'" , + 'Alvaro Nunes Melo' , + pgsql-performance@postgresql.org +In-Reply-To: <008401c5e44e$42600c20$1e21100a@ghwk02002147> +References: <008401c5e44e$42600c20$1e21100a@ghwk02002147> +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; + boundary="=-bSOP61PawZ62D/NruzET" +Organization: Catalyst .Net Ltd +Date: Tue, 08 Nov 2005 15:35:20 +1300 +Message-Id: <1131417320.5555.10.camel@ubu.mcmillan.net.nz> +Mime-Version: 1.0 +X-Mailer: Evolution 2.5.1 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/135 +X-Sequence-Number: 15392 + + +--=-bSOP61PawZ62D/NruzET +Content-Type: text/plain +Content-Transfer-Encoding: quoted-printable + +On Tue, 2005-11-08 at 10:22 +0000, Christian Paul B. Cosinas wrote: +> I see. +>=20 +> But How Can I put this in the Cron of my Linux Server? +> I really don't have an idea :) +> What I want to do is to loop around all the databases in my server and +> execute the vacuum of these 3 tables in each tables. + +I usually write a small shell script something like: + +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D +#!/bin/sh + +psql somedatabase <; + Tue, 8 Nov 2005 00:12:12 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 10321-06 + for ; + Tue, 8 Nov 2005 04:12:10 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id EBC42D7123 + for ; + Tue, 8 Nov 2005 00:12:09 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA84C7jL001159; + Mon, 7 Nov 2005 23:12:07 -0500 (EST) +To: "Craig A. James" +Cc: pgsql-performance@postgresql.org +Subject: Re: Expensive function and the optimizer +In-reply-to: <4370062B.4050202@modgraph-usa.com> +References: <4370062B.4050202@modgraph-usa.com> +Comments: In-reply-to "Craig A. James" + message dated "Mon, 07 Nov 2005 17:58:03 -0800" +Date: Mon, 07 Nov 2005 23:12:07 -0500 +Message-ID: <1158.1131423127@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/136 +X-Sequence-Number: 15393 + +"Craig A. James" writes: +> Is there some way to explain this cost to the optimizer in a permanent +> way, + +Nope, sorry. One thing you could do in the particular case at hand is +to rejigger the WHERE clause involving the function so that it requires +values from both tables and therefore can't be applied till after the +join is made. (If nothing else, give the function an extra dummy +argument that can be passed as a variable from the other table.) +This is an ugly and non-general solution of course. + +> The only way I've thought of is something like this: + +> select X.id from +> (select A.id, A.foo, A.row_num +> from A join B ON (A.id = B.id) +> where A.row_num >= 0 and A.row_num <= 43477 +> and B.id = 52) as X +> where myfunc(X.foo, 'FooBar') order by X.row_num; + +As written, that won't work because the planner will happily flatten the +query to the same thing you had before. You can put an OFFSET 0 into +the sub-select to prevent that from happening, but realize that this +creates a pretty impervious optimization fence ... the side-effects +might be undesirable when you come to look at real queries instead +of toy cases. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Tue Nov 8 05:01:28 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 588B5DA769 + for ; + Tue, 8 Nov 2005 05:01:20 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 09630-06 + for ; + Tue, 8 Nov 2005 09:01:15 +0000 (GMT) +X-Greylist: delayed 01:55:54.723731 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 1BF97D9D64 + for ; + Tue, 8 Nov 2005 05:01:07 -0400 (AST) +Received: from smtpauth04.mail.atl.earthlink.net + (smtpauth04.mail.atl.earthlink.net [209.86.89.64]) + by svr2.postgresql.org (Postfix) with ESMTP id 70CA2F0B9B + for ; + Tue, 8 Nov 2005 07:05:13 +0000 (GMT) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; + d=interserv.com; + b=lKPYg1AFam6B658W3zgSiBJnFHEW5ju4BQrr0Aerc3Be0n+4YYZXulMbL/VaciNS; + h=Received:Message-ID:Date:From:User-Agent:MIME-Version:To:Subject:Content-Type:Content-Transfer-Encoding:X-ELNK-Trace:X-Originating-IP; +Received: from c-67-172-134-193.hsd1.co.comcast.net ([67.172.134.193] + helo=[127.0.0.1]) + by smtpauth04.mail.atl.earthlink.net with asmtp (Exim 4.34) + id 1EZNXY-0005Hd-3d + for pgsql-performance@postgresql.org; Tue, 08 Nov 2005 02:05:08 -0500 +Message-ID: <43704E1D.80708@interserv.com> +Date: Tue, 08 Nov 2005 00:05:01 -0700 +From: Charlie Savage +User-Agent: Thunderbird 1.5 (Windows/20051025) +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Sort performance on large tables +Content-Type: text/plain; charset=UTF-8; format=flowed +Content-Transfer-Encoding: 7bit +X-ELNK-Trace: + e034cf2bd229a6001a54e280ff29e56240c5d2d4e9129c5a1d857c7956ec51dcc893167dfb778fe6350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c +X-Originating-IP: 67.172.134.193 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/137 +X-Sequence-Number: 15394 + +Hi everyone, + +I have a question about the performance of sort. + +Setup: Dell Dimension 3000, Suse 10, 1GB ram, PostgreSQL 8.1 RC 1 with +PostGIS, 1 built-in 80 GB IDE drive, 1 SATA Seagate 400GB drive. The +IDE drive has the OS and the WAL files, the SATA drive the database. + From hdparm the max IO for the IDE drive is about 50Mb/s and the SATA +drive is about 65Mb/s. Thus a very low-end machine - but it used just +for development (i.e., it is not a production machine) and the only +thing it does is run a PostgresSQL database. + +I have a staging table called completechain that holds US tiger data +(i.e., streets and addresses for the US). The table is approximately +18GB. Its big because there is a lot of data, but also because the +table is not normalized (it comes that way). + +I want to extract data out of the file, with the most important values +being stored in a column called tlid. The tlid field is an integer, and +the values are 98% unique. There is a second column called ogc_fid +which is unique (it is a serial field). I need to extract out unique +TLID's (doesn't matter which duplicate I get rid of). To do this I am +running this query: + +SELECT tlid, min(ogc_fid) +FROM completechain +GROUP BY tlid; + +The results from explain analyze are: + +"GroupAggregate (cost=10400373.80..11361807.88 rows=48071704 width=8) +(actual time=7311682.715..8315746.835 rows=47599910 loops=1)" +" -> Sort (cost=10400373.80..10520553.06 rows=48071704 width=8) +(actual time=7311682.682..7972304.777 rows=48199165 loops=1)" +" Sort Key: tlid" +" -> Seq Scan on completechain (cost=0.00..2228584.04 +rows=48071704 width=8) (actual time=27.514..773245.046 rows=48199165 +loops=1)" +"Total runtime: 8486057.185 ms" + +Doing a similar query produces the same results: + +SELECT DISTINCT ON (tlid), tlid, ogc_fid +FROM completechain; + +Note it takes over 10 times longer to do the sort than the full +sequential scan. + +Should I expect results like this? I realize that the computer is quite +low-end and is very IO bound for this query, but I'm still surprised +that the sort operation takes so long. + +Out of curiosity, I setup an Oracle database on the same machine with +the same data and ran the same query. Oracle was over an order of +magnitude faster. Looking at its query plan, it avoided the sort by +using "HASH GROUP BY." Does such a construct exist in PostgreSQL (I see +only hash joins)? + +Also as an experiment I forced oracle to do a sort by running this query: + +SELECT tlid, min(ogc_fid) +FROM completechain +GROUP BY tlid +ORDER BY tlid; + +Even with this, it was more than a magnitude faster than Postgresql. +Which makes me think I have somehow misconfigured postgresql (see the +relevant parts of postgresql.conf below). + +Any idea/help appreciated. + +Thanks, + +Charlie + + +------------------------------- + +#--------------------------------------------------------------------------- +# RESOURCE USAGE (except WAL) +#--------------------------------------------------------------------------- + +shared_buffers = 40000 # 40000 buffers * 8192 +bytes/buffer = 327,680,000 bytes +#shared_buffers = 1000 # min 16 or max_connections*2, 8KB each + +temp_buffers = 5000 +#temp_buffers = 1000 # min 100, 8KB each +#max_prepared_transactions = 5 # can be 0 or more +# note: increasing max_prepared_transactions costs ~600 bytes of shared +memory +# per transaction slot, plus lock space (see max_locks_per_transaction). + +work_mem = 16384 # in Kb +#work_mem = 1024 # min 64, size in KB + +maintenance_work_mem = 262144 # in kb +#maintenance_work_mem = 16384 # min 1024, size in KB +#max_stack_depth = 2048 # min 100, size in KB + +# - Free Space Map - + +max_fsm_pages = 60000 +#max_fsm_pages = 20000 # min max_fsm_relations*16, 6 bytes each + +#max_fsm_relations = 1000 # min 100, ~70 bytes each + +# - Kernel Resource Usage - + +#max_files_per_process = 1000 # min 25 +#preload_libraries = '' + +# - Cost-Based Vacuum Delay - + +#vacuum_cost_delay = 0 # 0-1000 milliseconds +#vacuum_cost_page_hit = 1 # 0-10000 credits +#vacuum_cost_page_miss = 10 # 0-10000 credits +#vacuum_cost_page_dirty = 20 # 0-10000 credits +#vacuum_cost_limit = 200 # 0-10000 credits + +# - Background writer - + +#bgwriter_delay = 200 # 10-10000 milliseconds between rounds +#bgwriter_lru_percent = 1.0 # 0-100% of LRU buffers scanned/round +#bgwriter_lru_maxpages = 5 # 0-1000 buffers max written/round +#bgwriter_all_percent = 0.333 # 0-100% of all buffers scanned/round +#bgwriter_all_maxpages = 5 # 0-1000 buffers max written/round + + +#--------------------------------------------------------------------------- +# WRITE AHEAD LOG +#--------------------------------------------------------------------------- + +# - Settings - + +fsync = on # turns forced synchronization on or off +#wal_sync_method = fsync # the default is the first option + # supported by the operating system: + # open_datasync + # fdatasync + # fsync + # fsync_writethrough + # open_sync +#full_page_writes = on # recover from partial page writes + +wal_buffers = 128 +#wal_buffers = 8 # min 4, 8KB each + +#commit_delay = 0 # range 0-100000, in microseconds +#commit_siblings = 5 # range 1-1000 + +# - Checkpoints - + +checkpoint_segments = 256 # 256 * 16Mb = 4,294,967,296 bytes +checkpoint_timeout = 1200 # 1200 seconds (20 minutes) +checkpoint_warning = 30 # in seconds, 0 is off + +#checkpoint_segments = 3 # in logfile segments, min 1, 16MB each +#checkpoint_timeout = 300 # range 30-3600, in seconds +#checkpoint_warning = 30 # in seconds, 0 is off + +# - Archiving - + +#archive_command = '' # command to use to archive a logfile + # segment + + +#--------------------------------------------------------------------------- +# QUERY TUNING +#--------------------------------------------------------------------------- + +# - Planner Method Configuration - + +#enable_bitmapscan = on +#enable_hashagg = on +#enable_hashjoin = on +#enable_indexscan = on +#enable_mergejoin = on +#enable_nestloop = on +#enable_seqscan = on +#enable_sort = on +#enable_tidscan = on + +# - Planner Cost Constants - + +effective_cache_size = 80000 # 80000 * 8192 = 655,360,000 bytes +#effective_cache_size = 1000 # typically 8KB each + +random_page_cost = 2.5 # units are one sequential page fetch +#random_page_cost = 4 # units are one sequential page fetch + # cost +#cpu_tuple_cost = 0.01 # (same) +#cpu_index_tuple_cost = 0.001 # (same) +#cpu_operator_cost = 0.0025 # (same) + +# - Genetic Query Optimizer - + +#geqo = on +#geqo_threshold = 12 +#geqo_effort = 5 # range 1-10 +#geqo_pool_size = 0 # selects default based on effort +#geqo_generations = 0 # selects default based on effort +#geqo_selection_bias = 2.0 # range 1.5-2.0 + +# - Other Planner Options - + +default_statistics_target = 100 # range 1-1000 +#default_statistics_target = 10 # range 1-1000 +#constraint_exclusion = off +#from_collapse_limit = 8 +#join_collapse_limit = 8 # 1 disables collapsing of explicit + # JOINs + + +#--------------------------------------------------------------------------- +#--------------------------------------------------------------------------- +# RUNTIME STATISTICS +#--------------------------------------------------------------------------- + +# - Statistics Monitoring - + +#log_parser_stats = off +#log_planner_stats = off +#log_executor_stats = off +#log_statement_stats = off + +# - Query/Index Statistics Collector - + +stats_start_collector = on +stats_command_string = on +stats_block_level = on +stats_row_level = on + +#stats_start_collector = on +#stats_command_string = off +#stats_block_level = off +#stats_row_level = off +#stats_reset_on_server_start = off + + +#--------------------------------------------------------------------------- +# AUTOVACUUM PARAMETERS +#--------------------------------------------------------------------------- + +autovacuum = true +autovacuum_naptime = 600 + +#autovacuum = false # enable autovacuum subprocess? +#autovacuum_naptime = 60 # time between autovacuum runs, in secs +#autovacuum_vacuum_threshold = 1000 # min # of tuple updates before + # vacuum +#autovacuum_analyze_threshold = 500 # min # of tuple updates before + # analyze +#autovacuum_vacuum_scale_factor = 0.4 # fraction of rel size before + # vacuum +#autovacuum_analyze_scale_factor = 0.2 # fraction of rel size before + # analyze +#autovacuum_vacuum_cost_delay = -1 # default vacuum cost delay for + # autovac, -1 means use + # vacuum_cost_delay +#autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for + # autovac, -1 means use + # vacuum_cost_ + + +---------------------- + +CREATE TABLE tiger.completechain +( + ogc_fid int4 NOT NULL DEFAULT +nextval('completechain_ogc_fid_seq'::regclass), + module varchar(8) NOT NULL, + tlid int4 NOT NULL, + side1 int4, + source varchar(1) NOT NULL, + fedirp varchar(2), + fename varchar(30), + fetype varchar(4), + fedirs varchar(2), + cfcc varchar(3) NOT NULL, + fraddl varchar(11), + toaddl varchar(11), + fraddr varchar(11), + toaddr varchar(11), + friaddl varchar(1), + toiaddl varchar(1), + friaddr varchar(1), + toiaddr varchar(1), + zipl int4, + zipr int4, + aianhhfpl int4, + aianhhfpr int4, + aihhtlil varchar(1), + aihhtlir varchar(1), + census1 varchar(1), + census2 varchar(1), + statel int4, + stater int4, + countyl int4, + countyr int4, + cousubl int4, + cousubr int4, + submcdl int4, + submcdr int4, + placel int4, + placer int4, + tractl int4, + tractr int4, + blockl int4, + blockr int4, + wkb_geometry public.geometry NOT NULL, + CONSTRAINT enforce_dims_wkb_geometry CHECK (ndims(wkb_geometry) = 2), + CONSTRAINT enforce_geotype_wkb_geometry CHECK +(geometrytype(wkb_geometry) = 'LINESTRING'::text OR wkb_geometry IS NULL), + CONSTRAINT enforce_srid_wkb_geometry CHECK (srid(wkb_geometry) = 4269) +) +WITHOUT OIDS; +ALTER TABLE tiger.completechain OWNER TO postgres; + + + + + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 22:00:08 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id E1394DA7EB + for ; + Mon, 7 Nov 2005 21:59:52 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 72938-01 + for ; + Tue, 8 Nov 2005 01:59:49 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mailer.eglobalreach.net (mail.heliustech.net [202.124.128.22]) + by svr1.postgresql.org (Postfix) with ESMTP id 0CB97D9E41 + for ; + Mon, 7 Nov 2005 21:59:49 -0400 (AST) +Received: from ghwk02002147 (localhost [127.0.0.1] (may be forged)) + by mailer.eglobalreach.net (8.11.6p2/) with ESMTP id jA81xjt17399; + Tue, 8 Nov 2005 09:59:47 +0800 +From: "Christian Paul B. Cosinas" +To: "'Alvaro Nunes Melo'" , + +Subject: Re: Temporary Table +Date: Tue, 8 Nov 2005 10:04:01 -0000 +Message-ID: <008201c5e44b$c0cdf390$1e21100a@ghwk02002147> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +X-Mailer: Microsoft Office Outlook 11 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1506 +Thread-Index: AcXaGuESJlWsZB6mToaTb7utC7xN7gKMJJlQ +In-Reply-To: <435F5F1C.1010703@atua.com.br> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.83 required=5 tests=[AWL=-0.762, + DATE_IN_FUTURE_06_12=1.498, URIBL_SBL=1.094] +X-Spam-Score: 1.83 +X-Spam-Level: * +X-Archive-Number: 200511/126 +X-Sequence-Number: 15383 + + +In what directory in my linux server will I find these 3 tables? + +-----Original Message----- +From: Alvaro Nunes Melo [mailto:al_nunes@atua.com.br] +Sent: Wednesday, October 26, 2005 10:49 AM +To: Christian Paul B. Cosinas +Subject: Re: [PERFORM] Temporary Table + +Christian Paul B. Cosinas wrote: + +>I am creating a temporary table in every function that I execute. +>Which I think is bout 100,000 temporary tables a day. +> +> +I think that a lot. ;) + +>What is the command for vacuuming these 3 tables? +> +> +VACUUM FULL pg_class; +VACUUM FULL pg_attribute; +VACUUM FULL pg_depend; + +I'm using this ones. Before using them, take a look in the size that this +tables are using in your HD, and compare to what you get after running this +commands. + + + +I choose Polesoft Lockspam to fight spam, and you? +http://www.polesoft.com/refer.html + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 22:04:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 1F33ED9AFA + for ; + Mon, 7 Nov 2005 22:04:46 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 72156-07 + for ; + Tue, 8 Nov 2005 02:04:42 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mailer.eglobalreach.net (mail.heliustech.net [202.124.128.22]) + by svr1.postgresql.org (Postfix) with ESMTP id 45B2CD8055 + for ; + Mon, 7 Nov 2005 22:04:43 -0400 (AST) +Received: from ghwk02002147 (localhost [127.0.0.1] (may be forged)) + by mailer.eglobalreach.net (8.11.6p2/) with ESMTP id jA824g417794; + Tue, 8 Nov 2005 10:04:43 +0800 +From: "Christian Paul B. Cosinas" +To: "'Alvaro Nunes Melo'" , + +Subject: Re: Temporary Table +Date: Tue, 8 Nov 2005 10:09:00 -0000 +Message-ID: <008301c5e44c$70eee900$1e21100a@ghwk02002147> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +X-Mailer: Microsoft Office Outlook 11 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1506 +Thread-Index: AcXaGuESJlWsZB6mToaTb7utC7xN7gKMUdQw +In-Reply-To: <435F5F1C.1010703@atua.com.br> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.853 required=5 tests=[AWL=-0.739, + DATE_IN_FUTURE_06_12=1.498, URIBL_SBL=1.094] +X-Spam-Score: 1.853 +X-Spam-Level: * +X-Archive-Number: 200511/127 +X-Sequence-Number: 15384 + +I try to run this command in my linux server. +VACUUM FULL pg_class; +VACUUM FULL pg_attribute; +VACUUM FULL pg_depend; + +But it give me the following error: + -bash: VACUUM: command not found + + + + + +I choose Polesoft Lockspam to fight spam, and you? +http://www.polesoft.com/refer.html + + +From pgsql-performance-owner@postgresql.org Mon Nov 7 22:17:51 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A6782DAA49 + for ; + Mon, 7 Nov 2005 22:17:49 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 76871-04 + for ; + Tue, 8 Nov 2005 02:17:46 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mailer.eglobalreach.net (mail.heliustech.net [202.124.128.22]) + by svr1.postgresql.org (Postfix) with ESMTP id 969E4DA48F + for ; + Mon, 7 Nov 2005 22:17:47 -0400 (AST) +Received: from ghwk02002147 (localhost [127.0.0.1] (may be forged)) + by mailer.eglobalreach.net (8.11.6p2/) with ESMTP id jA82Hi927629; + Tue, 8 Nov 2005 10:17:44 +0800 +From: "Christian Paul B. Cosinas" +To: "'Joshua D. Drake'" +Cc: "'Alvaro Nunes Melo'" , + +Subject: Re: Temporary Table +Date: Tue, 8 Nov 2005 10:22:01 -0000 +Message-ID: <008401c5e44e$42600c20$1e21100a@ghwk02002147> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +X-Mailer: Microsoft Office Outlook 11 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1506 +Thread-Index: AcXkCZ/+hrHRUvOURJiU8IRxQspFigARG0Sw +In-Reply-To: <4370091E.8060700@commandprompt.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.917 required=5 tests=[AWL=-0.675, + DATE_IN_FUTURE_06_12=1.498, URIBL_SBL=1.094] +X-Spam-Score: 1.917 +X-Spam-Level: * +X-Archive-Number: 200511/131 +X-Sequence-Number: 15388 + +I see. + +But How Can I put this in the Cron of my Linux Server? +I really don't have an idea :) +What I want to do is to loop around all the databases in my server and +execute the vacuum of these 3 tables in each tables. + +-----Original Message----- +From: Joshua D. Drake [mailto:jd@commandprompt.com] +Sent: Tuesday, November 08, 2005 2:11 AM +To: Christian Paul B. Cosinas +Cc: 'Alvaro Nunes Melo'; pgsql-performance@postgresql.org +Subject: Re: [PERFORM] Temporary Table + +Christian Paul B. Cosinas wrote: +> I try to run this command in my linux server. +> VACUUM FULL pg_class; +> VACUUM FULL pg_attribute; +> VACUUM FULL pg_depend; +> +> But it give me the following error: +> -bash: VACUUM: command not found + +That needs to be run from psql ... + +> +> +> +> +> +> I choose Polesoft Lockspam to fight spam, and you? +> http://www.polesoft.com/refer.html +> +> +> ---------------------------(end of +> broadcast)--------------------------- +> TIP 4: Have you searched our list archives? +> +> http://archives.postgresql.org + + +I choose Polesoft Lockspam to fight spam, and you? +http://www.polesoft.com/refer.html + + +From pgsql-performance-owner@postgresql.org Tue Nov 8 09:45:20 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id DEBCAD8E2A + for ; + Tue, 8 Nov 2005 09:45:18 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 92820-02 + for ; + Tue, 8 Nov 2005 13:45:13 +0000 (GMT) +X-Greylist: delayed 03:10:43.862651 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id D39BAD893A + for ; + Tue, 8 Nov 2005 09:45:11 -0400 (AST) +Received: from relay.icomedias.com (office.icomedias.com [62.99.232.80]) + by svr2.postgresql.org (Postfix) with ESMTP id A4AD3F0D67 + for ; + Tue, 8 Nov 2005 10:34:27 +0000 (GMT) +Received: from loki.icomedias.com ([10.192.17.128]) + by relay.icomedias.com (8.13.4/8.13.4) with ESMTP id jA8AYGDS031660; + Tue, 8 Nov 2005 11:34:16 +0100 +From: Mario Weilguni +To: pgsql-performance@postgresql.org +Subject: Re: 8.1 iss +Date: Tue, 8 Nov 2005 11:34:19 +0100 +User-Agent: KMail/1.8.92 +Cc: "PostgreSQL" +References: +In-Reply-To: +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200511081134.19495.mweilguni@sime.com> +X-Scanned-By: MIMEDefang 2.43 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.269 required=5 tests=[AWL=0.269] +X-Spam-Score: 0.269 +X-Spam-Level: +X-Archive-Number: 200511/139 +X-Sequence-Number: 15396 + +Am Montag, 7. November 2005 18:22 schrieb PostgreSQL: +> My most humble apologies to the pg development team (pg_lets?). +> +> I took Greg Stark's advice and set: +> +> shared_buffers = 10000 # was 50000 +> work_mem = 1048576 # 1Gb - was 16384 +> +> Also, I noticed that the EXPLAIN ANALYZE consistently thought reads would +> take longer than they actually did, so I decreased random_page_cost down to +> 1 (the server has a SATA Raid at level 10). + +Don't do that, use 1.5 or 2, setting it to 1 will only work well if you have +small databases fitting completly in memory. + + +From pgsql-performance-owner@postgresql.org Tue Nov 8 07:15:28 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 40CA0D7FCB + for ; + Tue, 8 Nov 2005 07:15:27 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 44321-03 + for ; + Tue, 8 Nov 2005 11:15:24 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.metronet.co.uk (mail.metronet.co.uk [213.162.97.75]) + by svr1.postgresql.org (Postfix) with ESMTP id 830D2D7FC7 + for ; + Tue, 8 Nov 2005 07:15:24 -0400 (AST) +Received: from mainbox.archonet.com + (84-51-143-99.archon037.adsl.metronet.co.uk [84.51.143.99]) + by smtp.metronet.co.uk (MetroNet Mail) with ESMTP + id 5BE90418966; Tue, 8 Nov 2005 11:15:20 +0000 (GMT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by mainbox.archonet.com (Postfix) with ESMTP id 87F0515EDA; + Tue, 8 Nov 2005 11:14:44 +0000 (GMT) +Received: from mainbox.archonet.com ([127.0.0.1]) + by localhost (mainbox [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id 24004-05; Tue, 8 Nov 2005 11:14:42 +0000 (GMT) +Received: from [192.168.1.17] (client17.office.archonet.com [192.168.1.17]) + by mainbox.archonet.com (Postfix) with ESMTP id CF29315ED9; + Tue, 8 Nov 2005 11:14:41 +0000 (GMT) +Message-ID: <437088A1.8090304@archonet.com> +Date: Tue, 08 Nov 2005 11:14:41 +0000 +From: Richard Huxton +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20051013) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Charlie Savage +Cc: pgsql-performance@postgresql.org +Subject: Re: Sort performance on large tables +References: <43704E1D.80708@interserv.com> +In-Reply-To: <43704E1D.80708@interserv.com> +Content-Type: text/plain; charset=UTF-8; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.033 required=5 tests=[AWL=0.033] +X-Spam-Score: 0.033 +X-Spam-Level: +X-Archive-Number: 200511/138 +X-Sequence-Number: 15395 + +Charlie Savage wrote: +> Hi everyone, +> +> I have a question about the performance of sort. + +> Note it takes over 10 times longer to do the sort than the full +> sequential scan. +> +> Should I expect results like this? I realize that the computer is quite +> low-end and is very IO bound for this query, but I'm still surprised +> that the sort operation takes so long. + +The sort will be spilling to disk, which will grind your I/O to a halt. + +> work_mem = 16384 # in Kb + +Try upping this. You should be able to issue "set work_mem = 100000" +before running your query IIRC. That should let PG do its sorting in +larger chunks. + +Also, if your most common access pattern is ordered via tlid look into +clustering the table on that. +-- + Richard Huxton + Archonet Ltd + +From pgsql-performance-owner@postgresql.org Tue Nov 8 12:32:10 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 90772D6836 + for ; + Tue, 8 Nov 2005 12:32:04 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 41596-07 + for ; + Tue, 8 Nov 2005 16:31:56 +0000 (GMT) +X-Greylist: delayed 03:11:33.466839 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id A9B1ED7B39 + for ; + Tue, 8 Nov 2005 12:31:52 -0400 (AST) +Received: from mailserver.sandvine.com (sandvine.com [199.243.201.138]) + by svr2.postgresql.org (Postfix) with ESMTP id D0E76F105E + for ; + Tue, 8 Nov 2005 13:20:24 +0000 (GMT) +X-MimeOLE: Produced By Microsoft Exchange V6.0.6603.0 +content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Sort performance on large tables +Date: Tue, 8 Nov 2005 08:19:44 -0500 +Message-ID: <2BCEB9A37A4D354AA276774EE13FB8C263B0BF@mailserver.sandvine.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Sort performance on large tables +Thread-Index: AcXkQ4HduZ54PzCmQ7a8YaRl+VD55AAI1WcA +From: "Marc Morin" +To: "Charlie Savage" , +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[AWL=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/141 +X-Sequence-Number: 15398 + +I have run into this type of query problem as well. I solved it in my +application by the following type of query. + +SELECT tlid +FROM completechain AS o +WHERE not exists (=20 + SELECT 1 + FROM completechain + WHERE tlid=3Do.tlid and ogc_fid!=3Do.ogc_fid +); + +Assumes of course that you have an index on tlid. + +> -----Original Message----- +> From: pgsql-performance-owner@postgresql.org=20 +> [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of=20 +> Charlie Savage +> Sent: Tuesday, November 08, 2005 2:05 AM +> To: pgsql-performance@postgresql.org +> Subject: [PERFORM] Sort performance on large tables +>=20 +> Hi everyone, +>=20 +> I have a question about the performance of sort. +>=20 +> Setup: Dell Dimension 3000, Suse 10, 1GB ram, PostgreSQL 8.1=20 +> RC 1 with PostGIS, 1 built-in 80 GB IDE drive, 1 SATA Seagate=20 +> 400GB drive. The IDE drive has the OS and the WAL files, the=20 +> SATA drive the database.=20 +> From hdparm the max IO for the IDE drive is about 50Mb/s and=20 +> the SATA drive is about 65Mb/s. Thus a very low-end machine=20 +> - but it used just for development (i.e., it is not a=20 +> production machine) and the only thing it does is run a=20 +> PostgresSQL database. +>=20 +> I have a staging table called completechain that holds US=20 +> tiger data (i.e., streets and addresses for the US). The=20 +> table is approximately 18GB. Its big because there is a lot=20 +> of data, but also because the table is not normalized (it=20 +> comes that way). +>=20 +> I want to extract data out of the file, with the most=20 +> important values being stored in a column called tlid. The=20 +> tlid field is an integer, and the values are 98% unique. =20 +> There is a second column called ogc_fid which is unique (it=20 +> is a serial field). I need to extract out unique TLID's=20 +> (doesn't matter which duplicate I get rid of). To do this I=20 +> am running this query: +>=20 +> SELECT tlid, min(ogc_fid) +> FROM completechain +> GROUP BY tlid; +>=20 +> The results from explain analyze are: +>=20 +> "GroupAggregate (cost=3D10400373.80..11361807.88 rows=3D48071704=20 +> width=3D8) (actual time=3D7311682.715..8315746.835 rows=3D47599910 = +loops=3D1)" +> " -> Sort (cost=3D10400373.80..10520553.06 rows=3D48071704=20 +> width=3D8) (actual time=3D7311682.682..7972304.777 rows=3D48199165 = +loops=3D1)" +> " Sort Key: tlid" +> " -> Seq Scan on completechain (cost=3D0.00..2228584.04=20 +> rows=3D48071704 width=3D8) (actual time=3D27.514..773245.046=20 +> rows=3D48199165 loops=3D1)" +> "Total runtime: 8486057.185 ms" +> =09 +> Doing a similar query produces the same results: +>=20 +> SELECT DISTINCT ON (tlid), tlid, ogc_fid FROM completechain; +>=20 +> Note it takes over 10 times longer to do the sort than the=20 +> full sequential scan. +>=20 +> Should I expect results like this? I realize that the=20 +> computer is quite low-end and is very IO bound for this=20 +> query, but I'm still surprised that the sort operation takes so long. +>=20 +> Out of curiosity, I setup an Oracle database on the same=20 +> machine with the same data and ran the same query. Oracle=20 +> was over an order of magnitude faster. Looking at its query=20 +> plan, it avoided the sort by using "HASH GROUP BY." Does=20 +> such a construct exist in PostgreSQL (I see only hash joins)? +>=20 +> Also as an experiment I forced oracle to do a sort by running=20 +> this query: +>=20 +> SELECT tlid, min(ogc_fid) +> FROM completechain +> GROUP BY tlid +> ORDER BY tlid; +>=20 +> Even with this, it was more than a magnitude faster than Postgresql.=20 +> Which makes me think I have somehow misconfigured postgresql=20 +> (see the relevant parts of postgresql.conf below). +>=20 +> Any idea/help appreciated. +>=20 +> Thanks, +>=20 +> Charlie +>=20 +>=20 +> ------------------------------- +>=20 +> #------------------------------------------------------------- +> -------------- +> # RESOURCE USAGE (except WAL) +> #------------------------------------------------------------- +> -------------- +>=20 +> shared_buffers =3D 40000 # 40000 buffers * 8192=20 +> bytes/buffer =3D 327,680,000 bytes +> #shared_buffers =3D 1000 # min 16 or=20 +> max_connections*2, 8KB each +>=20 +> temp_buffers =3D 5000 +> #temp_buffers =3D 1000 # min 100, 8KB each +> #max_prepared_transactions =3D 5 # can be 0 or more +> # note: increasing max_prepared_transactions costs ~600 bytes=20 +> of shared memory # per transaction slot, plus lock space (see=20 +> max_locks_per_transaction). +>=20 +> work_mem =3D 16384 # in Kb +> #work_mem =3D 1024 # min 64, size in KB +>=20 +> maintenance_work_mem =3D 262144 # in kb +> #maintenance_work_mem =3D 16384 # min 1024, size in KB +> #max_stack_depth =3D 2048 # min 100, size in KB +>=20 +> # - Free Space Map - +>=20 +> max_fsm_pages =3D 60000=09 +> #max_fsm_pages =3D 20000 # min=20 +> max_fsm_relations*16, 6 bytes each +>=20 +> #max_fsm_relations =3D 1000 # min 100, ~70 bytes each +>=20 +> # - Kernel Resource Usage - +>=20 +> #max_files_per_process =3D 1000 # min 25 +> #preload_libraries =3D '' +>=20 +> # - Cost-Based Vacuum Delay - +>=20 +> #vacuum_cost_delay =3D 0 # 0-1000 milliseconds +> #vacuum_cost_page_hit =3D 1 # 0-10000 credits +> #vacuum_cost_page_miss =3D 10 # 0-10000 credits +> #vacuum_cost_page_dirty =3D 20 # 0-10000 credits +> #vacuum_cost_limit =3D 200 # 0-10000 credits +>=20 +> # - Background writer - +>=20 +> #bgwriter_delay =3D 200 # 10-10000 milliseconds=20 +> between rounds +> #bgwriter_lru_percent =3D 1.0 # 0-100% of LRU buffers=20 +> scanned/round +> #bgwriter_lru_maxpages =3D 5 # 0-1000 buffers max=20 +> written/round +> #bgwriter_all_percent =3D 0.333 # 0-100% of all buffers=20 +> scanned/round +> #bgwriter_all_maxpages =3D 5 # 0-1000 buffers max=20 +> written/round +>=20 +>=20 +> #------------------------------------------------------------- +> -------------- +> # WRITE AHEAD LOG +> #------------------------------------------------------------- +> -------------- +>=20 +> # - Settings - +>=20 +> fsync =3D on # turns forced=20 +> synchronization on or off +> #wal_sync_method =3D fsync # the default is the=20 +> first option +> # supported by the=20 +> operating system: +> # open_datasync +> # fdatasync +> # fsync +> # fsync_writethrough +> # open_sync +> #full_page_writes =3D on # recover from=20 +> partial page writes +>=20 +> wal_buffers =3D 128 +> #wal_buffers =3D 8 # min 4, 8KB each +>=20 +> #commit_delay =3D 0 # range 0-100000, in=20 +> microseconds +> #commit_siblings =3D 5 # range 1-1000 +>=20 +> # - Checkpoints - +>=20 +> checkpoint_segments =3D 256 # 256 * 16Mb =3D=20 +> 4,294,967,296 bytes +> checkpoint_timeout =3D 1200 # 1200 seconds (20 minutes) +> checkpoint_warning =3D 30 # in seconds, 0 is off +>=20 +> #checkpoint_segments =3D 3 # in logfile segments,=20 +> min 1, 16MB each +> #checkpoint_timeout =3D 300 # range 30-3600, in seconds +> #checkpoint_warning =3D 30 # in seconds, 0 is off +>=20 +> # - Archiving - +>=20 +> #archive_command =3D '' # command to use to=20 +> archive a logfile +> # segment +>=20 +>=20 +> #------------------------------------------------------------- +> -------------- +> # QUERY TUNING +> #------------------------------------------------------------- +> -------------- +>=20 +> # - Planner Method Configuration - +>=20 +> #enable_bitmapscan =3D on +> #enable_hashagg =3D on +> #enable_hashjoin =3D on +> #enable_indexscan =3D on +> #enable_mergejoin =3D on +> #enable_nestloop =3D on +> #enable_seqscan =3D on +> #enable_sort =3D on +> #enable_tidscan =3D on +>=20 +> # - Planner Cost Constants - +>=20 +> effective_cache_size =3D 80000 # 80000 * 8192 =3D=20 +> 655,360,000 bytes +> #effective_cache_size =3D 1000 # typically 8KB each +>=20 +> random_page_cost =3D 2.5 # units are one=20 +> sequential page fetch +> #random_page_cost =3D 4 # units are one=20 +> sequential page fetch +> # cost +> #cpu_tuple_cost =3D 0.01 # (same) +> #cpu_index_tuple_cost =3D 0.001 # (same) +> #cpu_operator_cost =3D 0.0025 # (same) +>=20 +> # - Genetic Query Optimizer - +>=20 +> #geqo =3D on +> #geqo_threshold =3D 12 +> #geqo_effort =3D 5 # range 1-10 +> #geqo_pool_size =3D 0 # selects default based=20 +> on effort +> #geqo_generations =3D 0 # selects default based=20 +> on effort +> #geqo_selection_bias =3D 2.0 # range 1.5-2.0 +>=20 +> # - Other Planner Options - +>=20 +> default_statistics_target =3D 100 # range 1-1000 +> #default_statistics_target =3D 10 # range 1-1000 +> #constraint_exclusion =3D off +> #from_collapse_limit =3D 8 +> #join_collapse_limit =3D 8 # 1 disables collapsing=20 +> of explicit +> # JOINs +>=20 +>=20 +> #------------------------------------------------------------- +> -------------- +> #------------------------------------------------------------- +> -------------- +> # RUNTIME STATISTICS +> #------------------------------------------------------------- +> -------------- +>=20 +> # - Statistics Monitoring - +>=20 +> #log_parser_stats =3D off +> #log_planner_stats =3D off +> #log_executor_stats =3D off +> #log_statement_stats =3D off +>=20 +> # - Query/Index Statistics Collector - +>=20 +> stats_start_collector =3D on +> stats_command_string =3D on +> stats_block_level =3D on +> stats_row_level =3D on +>=20 +> #stats_start_collector =3D on +> #stats_command_string =3D off +> #stats_block_level =3D off +> #stats_row_level =3D off +> #stats_reset_on_server_start =3D off +>=20 +>=20 +> #------------------------------------------------------------- +> -------------- +> # AUTOVACUUM PARAMETERS +> #------------------------------------------------------------- +> -------------- +>=20 +> autovacuum =3D true +> autovacuum_naptime =3D 600 +>=20 +> #autovacuum =3D false # enable autovacuum subprocess? +> #autovacuum_naptime =3D 60 # time between=20 +> autovacuum runs, in secs +> #autovacuum_vacuum_threshold =3D 1000 # min # of tuple updates before +> # vacuum +> #autovacuum_analyze_threshold =3D 500 # min # of tuple updates before +> # analyze +> #autovacuum_vacuum_scale_factor =3D 0.4 # fraction of rel size before +> # vacuum +> #autovacuum_analyze_scale_factor =3D 0.2 # fraction of=20 +> rel size before +> # analyze +> #autovacuum_vacuum_cost_delay =3D -1 # default vacuum cost delay for +> # autovac, -1 means use +> # vacuum_cost_delay +> #autovacuum_vacuum_cost_limit =3D -1 # default vacuum cost limit for +> # autovac, -1 means use +> # vacuum_cost_ +>=20 +>=20 +> ---------------------- +>=20 +> CREATE TABLE tiger.completechain +> ( +> ogc_fid int4 NOT NULL DEFAULT +> nextval('completechain_ogc_fid_seq'::regclass), +> module varchar(8) NOT NULL, +> tlid int4 NOT NULL, +> side1 int4, +> source varchar(1) NOT NULL, +> fedirp varchar(2), +> fename varchar(30), +> fetype varchar(4), +> fedirs varchar(2), +> cfcc varchar(3) NOT NULL, +> fraddl varchar(11), +> toaddl varchar(11), +> fraddr varchar(11), +> toaddr varchar(11), +> friaddl varchar(1), +> toiaddl varchar(1), +> friaddr varchar(1), +> toiaddr varchar(1), +> zipl int4, +> zipr int4, +> aianhhfpl int4, +> aianhhfpr int4, +> aihhtlil varchar(1), +> aihhtlir varchar(1), +> census1 varchar(1), +> census2 varchar(1), +> statel int4, +> stater int4, +> countyl int4, +> countyr int4, +> cousubl int4, +> cousubr int4, +> submcdl int4, +> submcdr int4, +> placel int4, +> placer int4, +> tractl int4, +> tractr int4, +> blockl int4, +> blockr int4, +> wkb_geometry public.geometry NOT NULL, +> CONSTRAINT enforce_dims_wkb_geometry CHECK=20 +> (ndims(wkb_geometry) =3D 2), +> CONSTRAINT enforce_geotype_wkb_geometry CHECK +> (geometrytype(wkb_geometry) =3D 'LINESTRING'::text OR=20 +> wkb_geometry IS NULL), +> CONSTRAINT enforce_srid_wkb_geometry CHECK=20 +> (srid(wkb_geometry) =3D 4269) +> ) +> WITHOUT OIDS; +> ALTER TABLE tiger.completechain OWNER TO postgres; +>=20 +>=20 +>=20 +>=20 +>=20 +>=20 +> ---------------------------(end of=20 +> broadcast)--------------------------- +> TIP 5: don't forget to increase your free space map settings +>=20 +>=20 + +From pgsql-performance-owner@postgresql.org Tue Nov 8 12:25:08 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 76961D7AEE + for ; + Tue, 8 Nov 2005 12:25:07 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 40867-07 + for ; + Tue, 8 Nov 2005 16:25:05 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id CD7D6D7AE4 + for ; + Tue, 8 Nov 2005 12:25:05 -0400 (AST) +Received: from mail.mi8.com (d01gw02.mi8.com [63.240.6.46]) + by svr2.postgresql.org (Postfix) with ESMTP id E0662F1012 + for ; + Tue, 8 Nov 2005 16:25:04 +0000 (GMT) +Received: from 172.16.1.110 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D2)); Tue, 08 Nov 2005 11:24:58 -0500 +X-Server-Uuid: 7829E76E-BB9E-4995-8473-3C0929DF7DD1 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Tue, 8 Nov 2005 + 11:24:05 -0500 +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Subject: Re: Sort performance on large tables +Date: Tue, 8 Nov 2005 11:21:39 -0500 +Message-ID: <3E37B936B592014B978C4415F90D662D0193B9F0@MI8NYCMAIL06.Mi8.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Sort performance on large tables +Thread-Index: AcXkQ7vIMS+Ti1G7TxaOjDuOZh5zCQAO+Ixg +From: "Luke Lonergan" +To: "Charlie Savage" , + pgsql-performance@postgresql.org +X-OriginalArrivalTime: 08 Nov 2005 16:24:05.0378 (UTC) + FILETIME=[D6646E20:01C5E480] +X-WSS-ID: 6F6E0ED02RS1149045-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: quoted-printable +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/140 +X-Sequence-Number: 15397 + +Charlie,=20 + +> Should I expect results like this? I realize that the=20 +> computer is quite low-end and is very IO bound for this=20 +> query, but I'm still surprised that the sort operation takes so long. + +It's the sort performance of Postgres that's your problem. +=20 +> Out of curiosity, I setup an Oracle database on the same=20 +> machine with the same data and ran the same query. Oracle=20 +> was over an order of magnitude faster. Looking at its query=20 +> plan, it avoided the sort by using "HASH GROUP BY." Does=20 +> such a construct exist in PostgreSQL (I see only hash joins)? + +Yes, hashaggregate does a similar thing. You can force the planner to +do it, don't remember off the top of my head but someone else on-list +will. +=20 +> Also as an experiment I forced oracle to do a sort by running=20 +> this query: +>=20 +> SELECT tlid, min(ogc_fid) +> FROM completechain +> GROUP BY tlid +> ORDER BY tlid; +>=20 +> Even with this, it was more than a magnitude faster than Postgresql.=20 +> Which makes me think I have somehow misconfigured postgresql=20 +> (see the relevant parts of postgresql.conf below). + +Just as we find with a similar comparison (with a "popular commercial, +proprietary database" :-) Though some might suggest you increase +work_mem or other tuning suggestions to speed sorting, none work. In +fact, we find that increasing work_mem actually slows sorting slightly. + +We are commissioning an improved sorting routine for bizgres +(www.bizgres.org) which will be contributed to the postgres main, but +won't come out at least until 8.2 comes out, possibly 12 mos. In the +meantime, you will be able to use the new routine in the bizgres version +of postgres, possibly in the next couple of months. + +Also - we (Greenplum) are about to announce the public beta of the +bizgres MPP database, which will use all of your CPUs, and those of +other nodes in a cluster, for sorting. We see a linear scaling of sort +performance, so you could add CPUs and/or hosts and scale out of the +problem. + +Cheers, + +- Luke + + +From pgsql-performance-owner@postgresql.org Tue Nov 8 13:56:02 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id F11CDD8EE1 + for ; + Tue, 8 Nov 2005 13:55:59 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 67786-02 + for ; + Tue, 8 Nov 2005 17:55:57 +0000 (GMT) +X-Greylist: delayed 00:17:34.809212 by SQLgrey- +Received: from megazone.bigpanda.com (megazone.bigpanda.com [64.147.171.210]) + by svr1.postgresql.org (Postfix) with ESMTP id 55698D8EB7 + for ; + Tue, 8 Nov 2005 13:55:57 -0400 (AST) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id D4B5E35512; Tue, 8 Nov 2005 09:38:21 -0800 (PST) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id D30C6354F1; Tue, 8 Nov 2005 09:38:21 -0800 (PST) +Date: Tue, 8 Nov 2005 09:38:21 -0800 (PST) +From: Stephan Szabo +To: Luke Lonergan +Cc: Charlie Savage , + pgsql-performance@postgresql.org +Subject: Re: Sort performance on large tables +In-Reply-To: <3E37B936B592014B978C4415F90D662D0193B9F0@MI8NYCMAIL06.Mi8.com> +Message-ID: <20051108093500.N31541@megazone.bigpanda.com> +References: <3E37B936B592014B978C4415F90D662D0193B9F0@MI8NYCMAIL06.Mi8.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/142 +X-Sequence-Number: 15399 + +On Tue, 8 Nov 2005, Luke Lonergan wrote: + +> > SELECT tlid, min(ogc_fid) +> > FROM completechain +> > GROUP BY tlid +> > ORDER BY tlid; +> > +> > Even with this, it was more than a magnitude faster than Postgresql. +> > Which makes me think I have somehow misconfigured postgresql +> > (see the relevant parts of postgresql.conf below). +> +> Just as we find with a similar comparison (with a "popular commercial, +> proprietary database" :-) Though some might suggest you increase +> work_mem or other tuning suggestions to speed sorting, none work. In +> fact, we find that increasing work_mem actually slows sorting slightly. + +I wish you'd qualify your statements, because I can demonstrably show that +I can make sorts go faster on my machine at least by increasing work_mem +under some conditions. + +From pgsql-performance-owner@postgresql.org Tue Nov 8 15:10:56 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0A176D7CE2 + for ; + Tue, 8 Nov 2005 15:10:55 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 88771-03 + for ; + Tue, 8 Nov 2005 19:10:52 +0000 (GMT) +X-Greylist: delayed 02:45:48.137469 by SQLgrey- +Received: from mail.Mi8.com (d01gw03.mi8.com [63.240.6.42]) + by svr1.postgresql.org (Postfix) with ESMTP id 0E14AD7B14 + for ; + Tue, 8 Nov 2005 15:10:52 -0400 (AST) +Received: from 172.16.1.112 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D3)); Tue, 08 Nov 2005 14:10:43 -0500 +X-Server-Uuid: E847189C-FC88-4913-9CD4-DE66914F83C0 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Tue, 8 Nov 2005 + 14:09:09 -0500 +Received: from 67.103.45.218 ([67.103.45.218]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Tue, 8 Nov + 2005 14:09:08 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Tue, 08 Nov 2005 11:09:07 -0800 +Subject: Re: Sort performance on large tables +From: "Luke Lonergan" +To: "Stephan Szabo" , + "Simon Riggs" , + "Kurt Harriman" +Cc: pgsql-performance@postgresql.org +Message-ID: +Thread-Topic: [PERFORM] Sort performance on large tables +Thread-Index: AcXki0Y6Ii/3K6rFQ2e9hfcWTSaFmAADJ39f +In-Reply-To: <20051108093500.N31541@megazone.bigpanda.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 08 Nov 2005 19:09:09.0403 (UTC) + FILETIME=[E5A6B6B0:01C5E497] +X-WSS-ID: 6F6E27B92BW4092657-09-01 +Content-Type: multipart/alternative; + boundary=B_3214292948_8404042 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.408 required=5 tests=[AWL=0.154, + HTML_MESSAGE=0.001, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.408 +X-Spam-Level: * +X-Archive-Number: 200511/143 +X-Sequence-Number: 15400 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3214292948_8404042 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Stephan, + +On 11/8/05 9:38 AM, "Stephan Szabo" wrote: + +>> > +>> > Just as we find with a similar comparison (with a "popular commercial, +>> > proprietary database" :-) Though some might suggest you increase +>> > work_mem or other tuning suggestions to speed sorting, none work. In +>> > fact, we find that increasing work_mem actually slows sorting slightly= +. +>=20 +> I wish you'd qualify your statements, because I can demonstrably show tha= +t +> I can make sorts go faster on my machine at least by increasing work_mem +> under some conditions. +>=20 +Cool =AD can you provide your test case please? I=B9ll ask our folks to do the +same, but as I recall we did some pretty thorough testing and found that it +doesn=B9t help. Moreover, the conclusion was that the current algorithm isn=B9= +t +designed to use memory effectively. + +Recognize also that we=B9re looking for a factor of 10 or more improvement +here =AD this is not a small increase that=B9s needed. + +- Luke + + +--B_3214292948_8404042 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + + + +Re: [PERFORM] Sort performance on large tables + + +Steph= +an,
+
+On 11/8/05 9:38 AM, "Stephan Szabo" <sszabo@megazone.bigpanda.= +com> wrote:
+
+
>
+> Just as we find with a similar comparison (with a "popular commer= +cial,
+> proprietary database" :-) Though some might suggest you increase<= +BR> +> work_mem or other tuning suggestions to speed sorting, none work. &nbs= +p;In
+> fact, we find that increasing work_mem actually slows sorting slightly= +.
+
+I wish you'd qualify your statements, because I can demonstrably show that<= +BR> +I can make sorts go faster on my machine at least by increasing work_mem +under some conditions.
+
+
Cool – can you provide your test case please? &n= +bsp;I’ll ask our folks to do the same, but as I recall we did some pre= +tty thorough testing and found that it doesn’t help.  Moreover, t= +he conclusion was that the current algorithm isn’t designed to use mem= +ory effectively.
+
+Recognize also that we’re looking for a factor of 10 or more improvem= +ent here – this is not a small increase that’s needed.
+
+- Luke
+ + + + + +--B_3214292948_8404042-- + + +From pgsql-performance-owner@postgresql.org Tue Nov 8 16:48:47 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D8493D6815 + for ; + Tue, 8 Nov 2005 16:48:45 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 17309-02 + for ; + Tue, 8 Nov 2005 20:48:43 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from megazone.bigpanda.com (megazone.bigpanda.com [64.147.171.210]) + by svr1.postgresql.org (Postfix) with ESMTP id 7BF60D6805 + for ; + Tue, 8 Nov 2005 16:48:44 -0400 (AST) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id 09B8835630; Tue, 8 Nov 2005 12:48:45 -0800 (PST) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id C91743562E; Tue, 8 Nov 2005 12:48:45 -0800 (PST) +Date: Tue, 8 Nov 2005 12:48:45 -0800 (PST) +From: Stephan Szabo +To: Luke Lonergan +Cc: Simon Riggs , + Kurt Harriman , pgsql-performance@postgresql.org +Subject: Re: Sort performance on large tables +In-Reply-To: +Message-ID: <20051108124255.Y43056@megazone.bigpanda.com> +References: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=X-UNKNOWN +Content-Transfer-Encoding: QUOTED-PRINTABLE +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/144 +X-Sequence-Number: 15401 + + +On Tue, 8 Nov 2005, Luke Lonergan wrote: + +> Stephan, +> +> On 11/8/05 9:38 AM, "Stephan Szabo" wrote: +> +> >> > +> >> > Just as we find with a similar comparison (with a "popular commercia= +l, +> >> > proprietary database" :-) Though some might suggest you increase +> >> > work_mem or other tuning suggestions to speed sorting, none work. I= +n +> >> > fact, we find that increasing work_mem actually slows sorting slight= +ly. +> > +> > I wish you'd qualify your statements, because I can demonstrably show t= +hat +> > I can make sorts go faster on my machine at least by increasing work_me= +m +> > under some conditions. +> > +> Cool =AD can you provide your test case please? + +I probably should have added the wink smiley to make it obvious I was +talking about the simplest case, things that don't fit in work_mem at the +current level but for which it's easy to raise work_mem to cover. It's not +a big a gain as one might hope, but it does certainly drop again. + +> Recognize also that we=B9re looking for a factor of 10 or more improvemen= +t +> here =AD this is not a small increase that=B9s needed. + +I agree that we definately need help on that regard. I do see the effect +where raising work_mem lowers the performance up until that point. I just +think that it requires more care in the discussion than disregarding the +suggestions entirely especially since people are going to see this in the +archives. + +From pgsql-performance-owner@postgresql.org Tue Nov 8 18:06:11 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 19995D7AFA + for ; + Tue, 8 Nov 2005 18:06:10 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 35197-10 + for ; + Tue, 8 Nov 2005 22:06:07 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id E4F59D6873 + for ; + Tue, 8 Nov 2005 18:06:07 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id B6BFC31059; Tue, 8 Nov 2005 23:06:08 +0100 (MET) +From: Charlie Savage +X-Newsgroups: pgsql.performance +Subject: Re: Sort performance on large tables +Date: Tue, 08 Nov 2005 15:06:04 -0700 +Organization: Hub.Org Networking Services +Lines: 82 +Message-ID: +References: <43704E1D.80708@interserv.com> <437088A1.8090304@archonet.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=UTF-8; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +User-Agent: Thunderbird 1.5 (Windows/20051025) +In-Reply-To: <437088A1.8090304@archonet.com> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/145 +X-Sequence-Number: 15402 + +Thanks everyone for the feedback. + +I tried increasing work_mem: + +set work_mem to 300000; + +select tlid, min(ogc_fid) +from completechain +group by tld; + +The results are: + +"GroupAggregate (cost=9041602.80..10003036.88 rows=48071704 width=8) +(actual time=4371749.523..5106162.256 rows=47599910 loops=1)" +" -> Sort (cost=9041602.80..9161782.06 rows=48071704 width=8) (actual +time=4371690.894..4758660.433 rows=48199165 loops=1)" +" Sort Key: tlid" +" -> Seq Scan on completechain (cost=0.00..2228584.04 +rows=48071704 width=8) (actual time=49.518..805234.970 rows=48199165 +loops=1)" +"Total runtime: 5279988.127 ms" + +Thus the time decreased from 8486 seconds to 5279 seconds - which is a +nice improvement. However, that still leaves postgresql about 9 times +slower. + +I tried increasing work_mem up to 500000, but at that point the machine +started using its swap partition and performance degraded back to the +original values. + +Charlie + + +Richard Huxton wrote: + > Charlie Savage wrote: + >> Hi everyone, + >> + >> I have a question about the performance of sort. + > + >> Note it takes over 10 times longer to do the sort than the full + >> sequential scan. + >> + >> Should I expect results like this? I realize that the computer is + >> quite low-end and is very IO bound for this query, but I'm still + >> surprised that the sort operation takes so long. + > + > The sort will be spilling to disk, which will grind your I/O to a halt. + > + >> work_mem = 16384 # in Kb + > + > Try upping this. You should be able to issue "set work_mem = 100000" + > before running your query IIRC. That should let PG do its sorting in + > larger chunks. + > + > Also, if your most common access pattern is ordered via tlid look into + > clustering the table on that. + + + +Richard Huxton wrote: +> Charlie Savage wrote: +>> Hi everyone, +>> +>> I have a question about the performance of sort. +> +>> Note it takes over 10 times longer to do the sort than the full +>> sequential scan. +>> +>> Should I expect results like this? I realize that the computer is +>> quite low-end and is very IO bound for this query, but I'm still +>> surprised that the sort operation takes so long. +> +> The sort will be spilling to disk, which will grind your I/O to a halt. +> +>> work_mem = 16384 # in Kb +> +> Try upping this. You should be able to issue "set work_mem = 100000" +> before running your query IIRC. That should let PG do its sorting in +> larger chunks. +> +> Also, if your most common access pattern is ordered via tlid look into +> clustering the table on that. + +From pgsql-performance-owner@postgresql.org Tue Nov 8 18:26:23 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CED60D7AFA + for ; + Tue, 8 Nov 2005 18:26:22 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 42847-09 + for ; + Tue, 8 Nov 2005 22:26:19 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 64462D79A1 + for ; + Tue, 8 Nov 2005 18:26:20 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jA8MQL3u009450; + Tue, 8 Nov 2005 17:26:22 -0500 (EST) +To: Charlie Savage +Cc: pgsql-performance@postgresql.org +Subject: Re: Sort performance on large tables +In-reply-to: +References: <43704E1D.80708@interserv.com> <437088A1.8090304@archonet.com> + +Comments: In-reply-to Charlie Savage + message dated "Tue, 08 Nov 2005 15:06:04 -0700" +Date: Tue, 08 Nov 2005 17:26:21 -0500 +Message-ID: <9449.1131488781@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/146 +X-Sequence-Number: 15403 + +Charlie Savage writes: +> Thus the time decreased from 8486 seconds to 5279 seconds - which is a +> nice improvement. However, that still leaves postgresql about 9 times +> slower. + +BTW, what data type are you sorting, exactly? If it's a string type, +what is your LC_COLLATE setting? + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Tue Nov 8 22:31:48 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 2A77FD8A09 + for ; + Tue, 8 Nov 2005 22:31:47 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 13195-04 + for ; + Wed, 9 Nov 2005 02:31:40 +0000 (GMT) +X-Greylist: delayed 03:04:39.163601 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 8E165D86DA + for ; + Tue, 8 Nov 2005 22:31:42 -0400 (AST) +Received: from chilco.textdrive.com (chilco.textdrive.com [207.7.108.242]) + by svr2.postgresql.org (Postfix) with ESMTP id 5CC8BF0D05 + for ; + Tue, 8 Nov 2005 23:27:05 +0000 (GMT) +Received: from [192.168.15.103] + (pcp0012204803pcs.blairblvd.tn.nash.comcast.net [69.245.49.69]) + by chilco.textdrive.com (Postfix) with ESMTP id BBD8EDAC46; + Tue, 8 Nov 2005 23:27:07 +0000 (UTC) +In-Reply-To: <436FC767.1010702@telogis.com> +References: <436FC767.1010702@telogis.com> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: <80733A02-C543-4F12-93C3-9DE328522E21@sitening.com> +Cc: pgsql-performance@postgresql.org +Content-Transfer-Encoding: 7bit +From: "Thomas F. O'Connell" +Subject: Re: Figuring out which command failed +Date: Tue, 8 Nov 2005 17:26:28 -0600 +To: Ralph Mason +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.015 required=5 tests=[AWL=0.015] +X-Spam-Score: 0.015 +X-Spam-Level: +X-Archive-Number: 200511/150 +X-Sequence-Number: 15407 + + +On Nov 7, 2005, at 3:30 PM, Ralph Mason wrote: + +> Hi, +> +> I have a transaction that has multiple separate command in it +> (nothing unusual there). +> +> However sometimes one of the sql statements will fail and so the +> whole transaction fails. +> +> In some cases I could fix the failing statement if only I knew +> which one it was. Can anyone think of any way to get which +> statement actually failed from the error message? If the error +> message gave me the line of the failure it would be excellent, but +> it doesn't. Perhaps it would be easy for me to patch my version of +> Postgres to do that? +> +> I realize I could do this with 2 phase commit, but that isn't ready +> yet! +> +> Any thoughts or ideas are much appreciated +> +> Thanks +> Ralph + +2PC might not've been ready yesterday, but it's ready today! + +http://www.postgresql.org/docs/whatsnew + +-- +Thomas F. O'Connell +Database Architecture and Programming +Co-Founder +Sitening, LLC + +http://www.sitening.com/ +110 30th Avenue North, Suite 6 +Nashville, TN 37203-6320 +615-469-5150 +615-469-5151 (fax) + +From pgsql-performance-owner@postgresql.org Tue Nov 8 19:47:15 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6AAD5D7AFA + for ; + Tue, 8 Nov 2005 19:47:14 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 59607-10 + for ; + Tue, 8 Nov 2005 23:47:10 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id C2EC5D6805 + for ; + Tue, 8 Nov 2005 19:47:11 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id 358FD31059; Wed, 9 Nov 2005 00:47:13 +0100 (MET) +From: Charlie Savage +X-Newsgroups: pgsql.performance +Subject: Re: Sort performance on large tables +Date: Tue, 08 Nov 2005 16:47:10 -0700 +Organization: Hub.Org Networking Services +Lines: 18 +Message-ID: +References: <43704E1D.80708@interserv.com> <437088A1.8090304@archonet.com> + <9449.1131488781@sss.pgh.pa.us> +Mime-Version: 1.0 +Content-Type: text/plain; charset=UTF-8; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +User-Agent: Thunderbird 1.5 (Windows/20051025) +In-Reply-To: <9449.1131488781@sss.pgh.pa.us> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/147 +X-Sequence-Number: 15404 + +Its an int4. + +Charlie + +Tom Lane wrote: +> Charlie Savage writes: +>> Thus the time decreased from 8486 seconds to 5279 seconds - which is a +>> nice improvement. However, that still leaves postgresql about 9 times +>> slower. +> +> BTW, what data type are you sorting, exactly? If it's a string type, +> what is your LC_COLLATE setting? +> +> regards, tom lane +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 6: explain analyze is your friend +> + +From pgsql-performance-owner@postgresql.org Tue Nov 8 21:47:51 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id E9D10D8722 + for ; + Tue, 8 Nov 2005 21:47:50 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 97330-09 + for ; + Wed, 9 Nov 2005 01:47:47 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from houston.familyhealth.com.au (houston.au.fhnetwork.com + [203.22.197.21]) + by svr1.postgresql.org (Postfix) with ESMTP id B0C8DD86DA + for ; + Tue, 8 Nov 2005 21:47:48 -0400 (AST) +Received: from houston.familyhealth.com.au (localhost [127.0.0.1]) + by houston.familyhealth.com.au (Postfix) with ESMTP id 9F2412506B; + Wed, 9 Nov 2005 09:47:51 +0800 (WST) +Received: from [127.0.0.1] (work-40.internal [192.168.0.40]) + by houston.familyhealth.com.au (Postfix) with ESMTP id 5B8AC24FF7; + Wed, 9 Nov 2005 09:47:50 +0800 (WST) +Message-ID: <437155B3.3050507@familyhealth.com.au> +Date: Wed, 09 Nov 2005 09:49:39 +0800 +From: Christopher Kings-Lynne +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Charlie Savage +Cc: pgsql-performance@postgresql.org +Subject: Re: Sort performance on large tables +References: <43704E1D.80708@interserv.com> <437088A1.8090304@archonet.com> + +In-Reply-To: +Content-Type: text/plain; charset=UTF-8; format=flowed +Content-Transfer-Encoding: 7bit +X-familyhealth-MailScanner-Information: Please contact the ISP for more + information +X-familyhealth-MailScanner: Found to be clean +X-familyhealth-MailScanner-From: chriskl@familyhealth.com.au +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.037 required=5 tests=[AWL=0.037] +X-Spam-Score: 0.037 +X-Spam-Level: +X-Archive-Number: 200511/148 +X-Sequence-Number: 15405 + +I'd set up a trigger to maintain summary tables perhaps... + +Chris + + +Charlie Savage wrote: +> Thanks everyone for the feedback. +> +> I tried increasing work_mem: +> +> set work_mem to 300000; +> +> select tlid, min(ogc_fid) +> from completechain +> group by tld; +> +> The results are: +> +> "GroupAggregate (cost=9041602.80..10003036.88 rows=48071704 width=8) +> (actual time=4371749.523..5106162.256 rows=47599910 loops=1)" +> " -> Sort (cost=9041602.80..9161782.06 rows=48071704 width=8) (actual +> time=4371690.894..4758660.433 rows=48199165 loops=1)" +> " Sort Key: tlid" +> " -> Seq Scan on completechain (cost=0.00..2228584.04 +> rows=48071704 width=8) (actual time=49.518..805234.970 rows=48199165 +> loops=1)" +> "Total runtime: 5279988.127 ms" +> +> Thus the time decreased from 8486 seconds to 5279 seconds - which is a +> nice improvement. However, that still leaves postgresql about 9 times +> slower. +> +> I tried increasing work_mem up to 500000, but at that point the machine +> started using its swap partition and performance degraded back to the +> original values. +> +> Charlie +> +> +> Richard Huxton wrote: +> > Charlie Savage wrote: +> >> Hi everyone, +> >> +> >> I have a question about the performance of sort. +> > +> >> Note it takes over 10 times longer to do the sort than the full +> >> sequential scan. +> >> +> >> Should I expect results like this? I realize that the computer is +> >> quite low-end and is very IO bound for this query, but I'm still +> >> surprised that the sort operation takes so long. +> > +> > The sort will be spilling to disk, which will grind your I/O to a halt. +> > +> >> work_mem = 16384 # in Kb +> > +> > Try upping this. You should be able to issue "set work_mem = 100000" +> > before running your query IIRC. That should let PG do its sorting in +> > larger chunks. +> > +> > Also, if your most common access pattern is ordered via tlid look into +> > clustering the table on that. +> +> +> +> Richard Huxton wrote: +> +>> Charlie Savage wrote: +>> +>>> Hi everyone, +>>> +>>> I have a question about the performance of sort. +>> +>> +>>> Note it takes over 10 times longer to do the sort than the full +>>> sequential scan. +>>> +>>> Should I expect results like this? I realize that the computer is +>>> quite low-end and is very IO bound for this query, but I'm still +>>> surprised that the sort operation takes so long. +>> +>> +>> The sort will be spilling to disk, which will grind your I/O to a halt. +>> +>>> work_mem = 16384 # in Kb +>> +>> +>> Try upping this. You should be able to issue "set work_mem = 100000" +>> before running your query IIRC. That should let PG do its sorting in +>> larger chunks. +>> +>> Also, if your most common access pattern is ordered via tlid look into +>> clustering the table on that. +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 4: Have you searched our list archives? +> +> http://archives.postgresql.org + + +From pgsql-performance-owner@postgresql.org Tue Nov 8 22:23:53 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 411D2D6805 + for ; + Tue, 8 Nov 2005 22:23:51 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 10550-04 + for ; + Wed, 9 Nov 2005 02:23:47 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from zproxy.gmail.com (zproxy.gmail.com [64.233.162.201]) + by svr1.postgresql.org (Postfix) with ESMTP id B3877D6815 + for ; + Tue, 8 Nov 2005 22:23:49 -0400 (AST) +Received: by zproxy.gmail.com with SMTP id 14so55168nzn + for ; + Tue, 08 Nov 2005 18:23:54 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:mime-version:content-type; + b=UFRu4mL3QwpjxxqgJ4oKWvgDGd42DD/w0aWBjYe2KyYtkVRQXWMNvBlODcyMDpR0OQUmHZ1GQGN+CZ4EzKbcU2JxkVWLctSHaOt29eNV1IVV1odvvQK8bMRCkVIRbCC3lNV1Kfy5sCGjFgLLyVafiQCc5CwXlCF45rg+DgCFhIw= +Received: by 10.36.252.24 with SMTP id z24mr124565nzh; + Tue, 08 Nov 2005 18:23:54 -0800 (PST) +Received: by 10.36.252.36 with HTTP; Tue, 8 Nov 2005 18:23:54 -0800 (PST) +Message-ID: +Date: Wed, 9 Nov 2005 10:23:54 +0800 +From: William Lai +To: pgsql-performance@postgresql.org +Subject: +MIME-Version: 1.0 +Content-Type: multipart/alternative; + boundary="----=_Part_10573_10962096.1131503034224" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.975 required=5 tests=[HTML_MESSAGE=0.001, + HTML_SHORT_LENGTH=0.629, MISSING_SUBJECT=1.345] +X-Spam-Score: 1.975 +X-Spam-Level: * +X-Archive-Number: 200511/149 +X-Sequence-Number: 15406 + +------=_Part_10573_10962096.1131503034224 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline + +unsubscribe + +------=_Part_10573_10962096.1131503034224 +Content-Type: text/html; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline + +unsubscribe + +------=_Part_10573_10962096.1131503034224-- + +From pgsql-performance-owner@postgresql.org Wed Nov 9 01:49:56 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 3A8C7D8E00 + for ; + Wed, 9 Nov 2005 01:49:55 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 66145-08 + for ; + Wed, 9 Nov 2005 05:49:52 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (floppy.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id A904AD8B0C + for ; + Wed, 9 Nov 2005 01:49:51 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id 0733831058; Wed, 9 Nov 2005 06:49:51 +0100 (MET) +From: Charlie Savage +X-Newsgroups: pgsql.performance +Subject: Re: Sort performance on large tables +Date: Tue, 08 Nov 2005 22:49:43 -0700 +Organization: Hub.Org Networking Services +Lines: 412 +Message-ID: <43718DF7.6060609@interserv.com> +References: <2BCEB9A37A4D354AA276774EE13FB8C263B0BF@mailserver.sandvine.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +To: Marc Morin +User-Agent: Thunderbird 1.5 (Windows/20051025) +In-Reply-To: <2BCEB9A37A4D354AA276774EE13FB8C263B0BF@mailserver.sandvine.com> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/151 +X-Sequence-Number: 15408 + +Very interesting technique. It doesn't actually do quite what I want +since it returns all rows that do not have duplicates and not a complete +list of unique tlid values. But I could massage it to do what I want. + +Anyway, the timing: + + +"Seq Scan on completechain t1 (cost=0.00..218139733.60 rows=24099582 +width=4) (actual time=25.890..3404650.452 rows=47000655 loops=1)" +" Filter: (NOT (subplan))" +" SubPlan" +" -> Index Scan using idx_completechain_tlid on completechain t2 +(cost=0.00..4.48 rows=1 width=0) (actual time=0.059..0.059 rows=0 +loops=48199165)" +" Index Cond: ($0 = tlid)" +" Filter: ($1 <> ogc_fid)" +"Total runtime: 3551423.162 ms" +Marc Morin wrote: + +So a 60% reduction in time. Thanks again for the tip. + +Charlie + + +> I have run into this type of query problem as well. I solved it in my +> application by the following type of query. +> +> +> Assumes of course that you have an index on tlid. +> +>> -----Original Message----- +>> From: pgsql-performance-owner@postgresql.org +>> [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of +>> Charlie Savage +>> Sent: Tuesday, November 08, 2005 2:05 AM +>> To: pgsql-performance@postgresql.org +>> Subject: [PERFORM] Sort performance on large tables +>> +>> Hi everyone, +>> +>> I have a question about the performance of sort. +>> +>> Setup: Dell Dimension 3000, Suse 10, 1GB ram, PostgreSQL 8.1 +>> RC 1 with PostGIS, 1 built-in 80 GB IDE drive, 1 SATA Seagate +>> 400GB drive. The IDE drive has the OS and the WAL files, the +>> SATA drive the database. +>> From hdparm the max IO for the IDE drive is about 50Mb/s and +>> the SATA drive is about 65Mb/s. Thus a very low-end machine +>> - but it used just for development (i.e., it is not a +>> production machine) and the only thing it does is run a +>> PostgresSQL database. +>> +>> I have a staging table called completechain that holds US +>> tiger data (i.e., streets and addresses for the US). The +>> table is approximately 18GB. Its big because there is a lot +>> of data, but also because the table is not normalized (it +>> comes that way). +>> +>> I want to extract data out of the file, with the most +>> important values being stored in a column called tlid. The +>> tlid field is an integer, and the values are 98% unique. +>> There is a second column called ogc_fid which is unique (it +>> is a serial field). I need to extract out unique TLID's +>> (doesn't matter which duplicate I get rid of). To do this I +>> am running this query: +>> +>> SELECT tlid, min(ogc_fid) +>> FROM completechain +>> GROUP BY tlid; +>> +>> The results from explain analyze are: +>> +>> "GroupAggregate (cost=10400373.80..11361807.88 rows=48071704 +>> width=8) (actual time=7311682.715..8315746.835 rows=47599910 loops=1)" +>> " -> Sort (cost=10400373.80..10520553.06 rows=48071704 +>> width=8) (actual time=7311682.682..7972304.777 rows=48199165 loops=1)" +>> " Sort Key: tlid" +>> " -> Seq Scan on completechain (cost=0.00..2228584.04 +>> rows=48071704 width=8) (actual time=27.514..773245.046 +>> rows=48199165 loops=1)" +>> "Total runtime: 8486057.185 ms" +>> +>> Doing a similar query produces the same results: +>> +>> SELECT DISTINCT ON (tlid), tlid, ogc_fid FROM completechain; +>> +>> Note it takes over 10 times longer to do the sort than the +>> full sequential scan. +>> +>> Should I expect results like this? I realize that the +>> computer is quite low-end and is very IO bound for this +>> query, but I'm still surprised that the sort operation takes so long. +>> +>> Out of curiosity, I setup an Oracle database on the same +>> machine with the same data and ran the same query. Oracle +>> was over an order of magnitude faster. Looking at its query +>> plan, it avoided the sort by using "HASH GROUP BY." Does +>> such a construct exist in PostgreSQL (I see only hash joins)? +>> +>> Also as an experiment I forced oracle to do a sort by running +>> this query: +>> +>> SELECT tlid, min(ogc_fid) +>> FROM completechain +>> GROUP BY tlid +>> ORDER BY tlid; +>> +>> Even with this, it was more than a magnitude faster than Postgresql. +>> Which makes me think I have somehow misconfigured postgresql +>> (see the relevant parts of postgresql.conf below). +>> +>> Any idea/help appreciated. +>> +>> Thanks, +>> +>> Charlie +>> +>> +>> ------------------------------- +>> +>> #------------------------------------------------------------- +>> -------------- +>> # RESOURCE USAGE (except WAL) +>> #------------------------------------------------------------- +>> -------------- +>> +>> shared_buffers = 40000 # 40000 buffers * 8192 +>> bytes/buffer = 327,680,000 bytes +>> #shared_buffers = 1000 # min 16 or +>> max_connections*2, 8KB each +>> +>> temp_buffers = 5000 +>> #temp_buffers = 1000 # min 100, 8KB each +>> #max_prepared_transactions = 5 # can be 0 or more +>> # note: increasing max_prepared_transactions costs ~600 bytes +>> of shared memory # per transaction slot, plus lock space (see +>> max_locks_per_transaction). +>> +>> work_mem = 16384 # in Kb +>> #work_mem = 1024 # min 64, size in KB +>> +>> maintenance_work_mem = 262144 # in kb +>> #maintenance_work_mem = 16384 # min 1024, size in KB +>> #max_stack_depth = 2048 # min 100, size in KB +>> +>> # - Free Space Map - +>> +>> max_fsm_pages = 60000 +>> #max_fsm_pages = 20000 # min +>> max_fsm_relations*16, 6 bytes each +>> +>> #max_fsm_relations = 1000 # min 100, ~70 bytes each +>> +>> # - Kernel Resource Usage - +>> +>> #max_files_per_process = 1000 # min 25 +>> #preload_libraries = '' +>> +>> # - Cost-Based Vacuum Delay - +>> +>> #vacuum_cost_delay = 0 # 0-1000 milliseconds +>> #vacuum_cost_page_hit = 1 # 0-10000 credits +>> #vacuum_cost_page_miss = 10 # 0-10000 credits +>> #vacuum_cost_page_dirty = 20 # 0-10000 credits +>> #vacuum_cost_limit = 200 # 0-10000 credits +>> +>> # - Background writer - +>> +>> #bgwriter_delay = 200 # 10-10000 milliseconds +>> between rounds +>> #bgwriter_lru_percent = 1.0 # 0-100% of LRU buffers +>> scanned/round +>> #bgwriter_lru_maxpages = 5 # 0-1000 buffers max +>> written/round +>> #bgwriter_all_percent = 0.333 # 0-100% of all buffers +>> scanned/round +>> #bgwriter_all_maxpages = 5 # 0-1000 buffers max +>> written/round +>> +>> +>> #------------------------------------------------------------- +>> -------------- +>> # WRITE AHEAD LOG +>> #------------------------------------------------------------- +>> -------------- +>> +>> # - Settings - +>> +>> fsync = on # turns forced +>> synchronization on or off +>> #wal_sync_method = fsync # the default is the +>> first option +>> # supported by the +>> operating system: +>> # open_datasync +>> # fdatasync +>> # fsync +>> # fsync_writethrough +>> # open_sync +>> #full_page_writes = on # recover from +>> partial page writes +>> +>> wal_buffers = 128 +>> #wal_buffers = 8 # min 4, 8KB each +>> +>> #commit_delay = 0 # range 0-100000, in +>> microseconds +>> #commit_siblings = 5 # range 1-1000 +>> +>> # - Checkpoints - +>> +>> checkpoint_segments = 256 # 256 * 16Mb = +>> 4,294,967,296 bytes +>> checkpoint_timeout = 1200 # 1200 seconds (20 minutes) +>> checkpoint_warning = 30 # in seconds, 0 is off +>> +>> #checkpoint_segments = 3 # in logfile segments, +>> min 1, 16MB each +>> #checkpoint_timeout = 300 # range 30-3600, in seconds +>> #checkpoint_warning = 30 # in seconds, 0 is off +>> +>> # - Archiving - +>> +>> #archive_command = '' # command to use to +>> archive a logfile +>> # segment +>> +>> +>> #------------------------------------------------------------- +>> -------------- +>> # QUERY TUNING +>> #------------------------------------------------------------- +>> -------------- +>> +>> # - Planner Method Configuration - +>> +>> #enable_bitmapscan = on +>> #enable_hashagg = on +>> #enable_hashjoin = on +>> #enable_indexscan = on +>> #enable_mergejoin = on +>> #enable_nestloop = on +>> #enable_seqscan = on +>> #enable_sort = on +>> #enable_tidscan = on +>> +>> # - Planner Cost Constants - +>> +>> effective_cache_size = 80000 # 80000 * 8192 = +>> 655,360,000 bytes +>> #effective_cache_size = 1000 # typically 8KB each +>> +>> random_page_cost = 2.5 # units are one +>> sequential page fetch +>> #random_page_cost = 4 # units are one +>> sequential page fetch +>> # cost +>> #cpu_tuple_cost = 0.01 # (same) +>> #cpu_index_tuple_cost = 0.001 # (same) +>> #cpu_operator_cost = 0.0025 # (same) +>> +>> # - Genetic Query Optimizer - +>> +>> #geqo = on +>> #geqo_threshold = 12 +>> #geqo_effort = 5 # range 1-10 +>> #geqo_pool_size = 0 # selects default based +>> on effort +>> #geqo_generations = 0 # selects default based +>> on effort +>> #geqo_selection_bias = 2.0 # range 1.5-2.0 +>> +>> # - Other Planner Options - +>> +>> default_statistics_target = 100 # range 1-1000 +>> #default_statistics_target = 10 # range 1-1000 +>> #constraint_exclusion = off +>> #from_collapse_limit = 8 +>> #join_collapse_limit = 8 # 1 disables collapsing +>> of explicit +>> # JOINs +>> +>> +>> #------------------------------------------------------------- +>> -------------- +>> #------------------------------------------------------------- +>> -------------- +>> # RUNTIME STATISTICS +>> #------------------------------------------------------------- +>> -------------- +>> +>> # - Statistics Monitoring - +>> +>> #log_parser_stats = off +>> #log_planner_stats = off +>> #log_executor_stats = off +>> #log_statement_stats = off +>> +>> # - Query/Index Statistics Collector - +>> +>> stats_start_collector = on +>> stats_command_string = on +>> stats_block_level = on +>> stats_row_level = on +>> +>> #stats_start_collector = on +>> #stats_command_string = off +>> #stats_block_level = off +>> #stats_row_level = off +>> #stats_reset_on_server_start = off +>> +>> +>> #------------------------------------------------------------- +>> -------------- +>> # AUTOVACUUM PARAMETERS +>> #------------------------------------------------------------- +>> -------------- +>> +>> autovacuum = true +>> autovacuum_naptime = 600 +>> +>> #autovacuum = false # enable autovacuum subprocess? +>> #autovacuum_naptime = 60 # time between +>> autovacuum runs, in secs +>> #autovacuum_vacuum_threshold = 1000 # min # of tuple updates before +>> # vacuum +>> #autovacuum_analyze_threshold = 500 # min # of tuple updates before +>> # analyze +>> #autovacuum_vacuum_scale_factor = 0.4 # fraction of rel size before +>> # vacuum +>> #autovacuum_analyze_scale_factor = 0.2 # fraction of +>> rel size before +>> # analyze +>> #autovacuum_vacuum_cost_delay = -1 # default vacuum cost delay for +>> # autovac, -1 means use +>> # vacuum_cost_delay +>> #autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for +>> # autovac, -1 means use +>> # vacuum_cost_ +>> +>> +>> ---------------------- +>> +>> CREATE TABLE tiger.completechain +>> ( +>> ogc_fid int4 NOT NULL DEFAULT +>> nextval('completechain_ogc_fid_seq'::regclass), +>> module varchar(8) NOT NULL, +>> tlid int4 NOT NULL, +>> side1 int4, +>> source varchar(1) NOT NULL, +>> fedirp varchar(2), +>> fename varchar(30), +>> fetype varchar(4), +>> fedirs varchar(2), +>> cfcc varchar(3) NOT NULL, +>> fraddl varchar(11), +>> toaddl varchar(11), +>> fraddr varchar(11), +>> toaddr varchar(11), +>> friaddl varchar(1), +>> toiaddl varchar(1), +>> friaddr varchar(1), +>> toiaddr varchar(1), +>> zipl int4, +>> zipr int4, +>> aianhhfpl int4, +>> aianhhfpr int4, +>> aihhtlil varchar(1), +>> aihhtlir varchar(1), +>> census1 varchar(1), +>> census2 varchar(1), +>> statel int4, +>> stater int4, +>> countyl int4, +>> countyr int4, +>> cousubl int4, +>> cousubr int4, +>> submcdl int4, +>> submcdr int4, +>> placel int4, +>> placer int4, +>> tractl int4, +>> tractr int4, +>> blockl int4, +>> blockr int4, +>> wkb_geometry public.geometry NOT NULL, +>> CONSTRAINT enforce_dims_wkb_geometry CHECK +>> (ndims(wkb_geometry) = 2), +>> CONSTRAINT enforce_geotype_wkb_geometry CHECK +>> (geometrytype(wkb_geometry) = 'LINESTRING'::text OR +>> wkb_geometry IS NULL), +>> CONSTRAINT enforce_srid_wkb_geometry CHECK +>> (srid(wkb_geometry) = 4269) +>> ) +>> WITHOUT OIDS; +>> ALTER TABLE tiger.completechain OWNER TO postgres; +>> +>> +>> +>> +>> +>> +>> ---------------------------(end of +>> broadcast)--------------------------- +>> TIP 5: don't forget to increase your free space map settings +>> +>> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 5: don't forget to increase your free space map settings +> + +From pgsql-performance-owner@postgresql.org Wed Nov 9 05:38:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 46FC2D7B3A + for ; + Wed, 9 Nov 2005 05:38:45 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 68834-09 + for ; + Wed, 9 Nov 2005 09:38:39 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtp.nildram.co.uk (smtp.nildram.co.uk [195.112.4.54]) + by svr1.postgresql.org (Postfix) with ESMTP id C6ED0D6805 + for ; + Wed, 9 Nov 2005 05:38:40 -0400 (AST) +Received: from 192.168.0.3 (unknown [84.12.200.148]) + by smtp.nildram.co.uk (Postfix) with ESMTP + id A63AE24D685; Wed, 9 Nov 2005 09:38:35 +0000 (GMT) +Subject: Re: Sort performance on large tables +From: Simon Riggs +To: Charlie Savage , + Luke Lonergan +Cc: pgsql-performance@postgresql.org +In-Reply-To: <43704E1D.80708@interserv.com> +References: <43704E1D.80708@interserv.com> +Content-Type: text/plain +Organization: 2nd Quadrant +Date: Wed, 09 Nov 2005 09:35:55 +0000 +Message-Id: <1131528955.8300.2101.camel@localhost.localdomain> +Mime-Version: 1.0 +X-Mailer: Evolution 2.0.2 (2.0.2-3) +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.01 required=5 tests=[AWL=0.010] +X-Spam-Score: 0.01 +X-Spam-Level: +X-Archive-Number: 200511/152 +X-Sequence-Number: 15409 + +On Tue, 2005-11-08 at 00:05 -0700, Charlie Savage wrote: + +> Setup: Dell Dimension 3000, Suse 10, 1GB ram, PostgreSQL 8.1 RC 1 with + +> I want to extract data out of the file, with the most important values +> being stored in a column called tlid. The tlid field is an integer, and +> the values are 98% unique. There is a second column called ogc_fid +> which is unique (it is a serial field). I need to extract out unique +> TLID's (doesn't matter which duplicate I get rid of). To do this I am +> running this query: +> +> SELECT tlid, min(ogc_fid) +> FROM completechain +> GROUP BY tlid; +> +> The results from explain analyze are: +> +> "GroupAggregate (cost=10400373.80..11361807.88 rows=48071704 width=8) +> (actual time=7311682.715..8315746.835 rows=47599910 loops=1)" +> " -> Sort (cost=10400373.80..10520553.06 rows=48071704 width=8) +> (actual time=7311682.682..7972304.777 rows=48199165 loops=1)" +> " Sort Key: tlid" +> " -> Seq Scan on completechain (cost=0.00..2228584.04 +> rows=48071704 width=8) (actual time=27.514..773245.046 rows=48199165 +> loops=1)" +> "Total runtime: 8486057.185 ms" + +> Should I expect results like this? I realize that the computer is quite +> low-end and is very IO bound for this query, but I'm still surprised +> that the sort operation takes so long. +> +> Out of curiosity, I setup an Oracle database on the same machine with +> the same data and ran the same query. Oracle was over an order of +> magnitude faster. Looking at its query plan, it avoided the sort by +> using "HASH GROUP BY." Does such a construct exist in PostgreSQL (I see +> only hash joins)? + +PostgreSQL can do HashAggregates as well as GroupAggregates, just like +Oracle. HashAggs avoid the sort phase, so would improve performance +considerably. The difference in performance you are getting is because +of the different plan used. Did you specifically do anything to Oracle +to help it get that plan, or was it a pure out-of-the-box install (or +maybe even a "set this up for Data Warehousing" install)? + +To get a HashAgg plan, you need to be able to fit all of the unique +values in memory. That would be 98% of 48071704 rows, each 8+ bytes +wide, giving a HashAgg memory sizing of over 375MB. You must allocate +memory of the next power of two above the level you want, so we would +need to allocate 512MB to work_mem before it would consider using a +HashAgg. + +Can you let us know how high you have to set work_mem before an EXPLAIN +(not EXPLAIN ANALYZE) chooses the HashAgg plan? + +Please be aware that publishing Oracle performance results is against +the terms of their licence and we seek to be both fair and legitimate, +especially within this public discussion forum. + +Best Regards, Simon Riggs + + +From pgsql-performance-owner@postgresql.org Wed Nov 9 08:08:45 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 26123D8B60 + for ; + Wed, 9 Nov 2005 08:08:44 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 17356-03 + for ; + Wed, 9 Nov 2005 12:08:39 +0000 (GMT) +X-Greylist: delayed 01:05:09.043067 by SQLgrey- +Received: from h6608.serverkompetenz.net (gpg-keyserver.de [81.169.179.29]) + by svr1.postgresql.org (Postfix) with ESMTP id 93DD4D70C0 + for ; + Wed, 9 Nov 2005 08:08:40 -0400 (AST) +Received: from [217.186.218.187] (helo=[192.168.0.51]) + by h6608.serverkompetenz.net with asmtp (Exim 4.34) + id 1EZoks-0002Hz-7m + for pgsql-performance@postgresql.org; Wed, 09 Nov 2005 13:08:42 +0100 +Message-ID: <4371E6A7.50808@web.de> +Date: Wed, 09 Nov 2005 13:08:07 +0100 +From: Jan Kesten +User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Improving performance on multicolumn query +X-Enigmail-Version: 0.92.0.0 +OpenPGP: id=82201FC4; + url=http://gpg-keyserver.de +Content-Type: multipart/mixed; boundary="------------050207070808000904010206" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/153 +X-Sequence-Number: 15410 + +This is a multi-part message in MIME format. +--------------050207070808000904010206 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: 7bit + + +Hi, all! + +I've been using postgresql for a long time now, but today I had some +problem I couldn't solve properly - hope here some more experienced +users have some hint's for me. + +First, I'm using postgresql 7.4.7 on a 2GHz machine having 1.5GByte RAM +and I have a table with about 220 columns and 20000 rows - and the first +five columns build a primary key (and a unique index). + +Now my problem: I need really many queries of rows using it's primary +key and fetching about five different columns but these are quite slow +(about 10 queries per second and as I have some other databases which +can have about 300 queries per second I think this is slow): + +transfer=> explain analyse SELECT * FROM test WHERE test_a=9091150001 +AND test_b=1 AND test_c=2 AND test_d=0 AND test_e=0; + + Index Scan using test_idx on test (cost=0.00..50.27 rows=1 width=1891) +(actual time=0.161..0.167 rows=1 loops=1) + Index Cond: (test_a = 9091150001::bigint) + Filter: ((test_b = 1) AND (test_c = 2) AND (test_d = 0) AND (test_e 0)) + +So, what to do to speed things up? If I understand correctly this +output, the planner uses my index (test_idx is the same as test_pkey +created along with the table), but only for the first column. + +Accidently I can't refactor these tables as they were given to me. + +Thanks for any hint! +Jan + + +--------------050207070808000904010206 +Content-Type: application/pgp-signature; + name="signature.asc" +Content-Transfer-Encoding: base64 +Content-Disposition: inline; + filename="signature.asc" + +LS0tLS1CRUdJTiBQR1AgU0lHTkFUVVJFLS0tLS0NClZlcnNpb246IEdudVBHIHYxLjIuNCAo +TWluZ1czMikNCkNvbW1lbnQ6IFVzaW5nIEdudVBHIHdpdGggVGh1bmRlcmJpcmQgLSBodHRw +Oi8vZW5pZ21haWwubW96ZGV2Lm9yZw0KDQppRDhEQlFGRGNkZGV2dm1Da0lJZ0g4UVJBc3lX +QUo0M1BGVUhCdmVlanBCTk1hRC9DczgwdjBnb1RnQ2dyMTZaDQprNUVuWEtKZDZQZjE4eHRi +dEY1Y05uUT0NCj1wWmJvDQotLS0tLUVORCBQR1AgU0lHTkFUVVJFLS0tLS0NCg0K +--------------050207070808000904010206-- + +From pgsql-performance-owner@postgresql.org Wed Nov 9 11:51:48 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8F153D9B47 + for ; + Wed, 9 Nov 2005 11:51:47 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 82118-02 + for ; + Wed, 9 Nov 2005 15:51:41 +0000 (GMT) +X-Greylist: delayed 03:07:14.708408 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id C227ED967B + for ; + Wed, 9 Nov 2005 11:51:41 -0400 (AST) +Received: from cassarossa.samfundet.no (cassarossa.samfundet.no + [129.241.93.19]) + by svr2.postgresql.org (Postfix) with ESMTP id 53B3BF0F48 + for ; + Wed, 9 Nov 2005 12:44:30 +0000 (GMT) +Received: from trofast.sesse.net ([129.241.93.32]) + by cassarossa.samfundet.no with esmtp (Exim 4.50) id 1EZpJQ-0002LS-SO + for pgsql-performance@postgresql.org; Wed, 09 Nov 2005 13:44:26 +0100 +Received: from sesse by trofast.sesse.net with local (Exim 3.36 #1 (Debian)) + id 1EZpJV-0002Nd-00 + for ; Wed, 09 Nov 2005 13:44:29 +0100 +Date: Wed, 9 Nov 2005 13:44:29 +0100 +From: "Steinar H. Gunderson" +To: pgsql-performance@postgresql.org +Subject: Re: Improving performance on multicolumn query +Message-ID: <20051109124429.GA9127@uio.no> +Mail-Followup-To: pgsql-performance@postgresql.org +References: <4371E6A7.50808@web.de> +MIME-Version: 1.0 +Content-Type: text/plain; charset=utf-8 +Content-Disposition: inline +In-Reply-To: <4371E6A7.50808@web.de> +X-Operating-System: Linux 2.6.14 on a i686 +X-Message-Flag: Outlook? --> http://www.mozilla.org/products/thunderbird/ +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.009 required=5 tests=[AWL=0.009] +X-Spam-Score: 0.009 +X-Spam-Level: +X-Archive-Number: 200511/157 +X-Sequence-Number: 15414 + +On Wed, Nov 09, 2005 at 01:08:07PM +0100, Jan Kesten wrote: +> Now my problem: I need really many queries of rows using it's primary +> key and fetching about five different columns but these are quite slow +> (about 10 queries per second and as I have some other databases which +> can have about 300 queries per second I think this is slow): +> +> transfer=> explain analyse SELECT * FROM test WHERE test_a=9091150001 +> AND test_b=1 AND test_c=2 AND test_d=0 AND test_e=0; +> +> Index Scan using test_idx on test (cost=0.00..50.27 rows=1 width=1891) +> (actual time=0.161..0.167 rows=1 loops=1) +> Index Cond: (test_a = 9091150001::bigint) +> Filter: ((test_b = 1) AND (test_c = 2) AND (test_d = 0) AND (test_e 0)) + +You don't post your table definitions (please do), but it looks like test_b, +test_c, test_d and test_e might be bigints? If so, you may want to do +explicit "AND test_b=1::bigint AND test_c=2::bigint" etc. -- 7.4 doesn't +figure this out for you. (8.0 and higher does.) + +/* Steinar */ +-- +Homepage: http://www.sesse.net/ + +From pgsql-performance-owner@postgresql.org Wed Nov 9 08:55:35 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id AD2FDD995D + for ; + Wed, 9 Nov 2005 08:55:33 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 29643-08 + for ; + Wed, 9 Nov 2005 12:55:30 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.metronet.co.uk (mail.metronet.co.uk [213.162.97.75]) + by svr1.postgresql.org (Postfix) with ESMTP id C3D1FD98DF + for ; + Wed, 9 Nov 2005 08:55:31 -0400 (AST) +Received: from mainbox.archonet.com + (84-51-143-99.archon037.adsl.metronet.co.uk [84.51.143.99]) + by smtp.metronet.co.uk (MetroNet Mail) with ESMTP + id B36AE40C1C3; Wed, 9 Nov 2005 12:55:26 +0000 (GMT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by mainbox.archonet.com (Postfix) with ESMTP id CD22915EDB; + Wed, 9 Nov 2005 12:54:59 +0000 (GMT) +Received: from mainbox.archonet.com ([127.0.0.1]) + by localhost (mainbox [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id 25179-04; Wed, 9 Nov 2005 12:54:51 +0000 (GMT) +Received: from [192.168.1.17] (client17.office.archonet.com [192.168.1.17]) + by mainbox.archonet.com (Postfix) with ESMTP id 34AAF15EDA; + Wed, 9 Nov 2005 12:54:46 +0000 (GMT) +Message-ID: <4371F195.6060204@archonet.com> +Date: Wed, 09 Nov 2005 12:54:45 +0000 +From: Richard Huxton +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20051013) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Jan Kesten +Cc: pgsql-performance@postgresql.org +Subject: Re: Improving performance on multicolumn query +References: <4371E6A7.50808@web.de> +In-Reply-To: <4371E6A7.50808@web.de> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.032 required=5 tests=[AWL=0.032] +X-Spam-Score: 0.032 +X-Spam-Level: +X-Archive-Number: 200511/154 +X-Sequence-Number: 15411 + +Jan Kesten wrote: +> +> First, I'm using postgresql 7.4.7 on a 2GHz machine having 1.5GByte RAM +> and I have a table with about 220 columns and 20000 rows - and the first +> five columns build a primary key (and a unique index). + +> transfer=> explain analyse SELECT * FROM test WHERE test_a=9091150001 +> AND test_b=1 AND test_c=2 AND test_d=0 AND test_e=0; +> +> Index Scan using test_idx on test (cost=0.00..50.27 rows=1 width=1891) +> (actual time=0.161..0.167 rows=1 loops=1) +> Index Cond: (test_a = 9091150001::bigint) +> Filter: ((test_b = 1) AND (test_c = 2) AND (test_d = 0) AND (test_e 0)) + +This says it's taking less than a millisecond - which is almost +certainly too fast to measure accurately anyway. Are you sure this query +is the problem? + +> So, what to do to speed things up? If I understand correctly this +> output, the planner uses my index (test_idx is the same as test_pkey +> created along with the table), but only for the first column. + +1. Are all of test_a/b/c/d/e bigint rather than int? +2. Have you tried explicitly casting your query parameters? +...WHERE test_a=123::bigint AND test_b=456::bigint... + +-- + Richard Huxton + Archonet Ltd + +From pgsql-performance-owner@postgresql.org Wed Nov 9 09:00:19 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8AD02D99AF + for ; + Wed, 9 Nov 2005 09:00:18 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 29568-09 + for ; + Wed, 9 Nov 2005 13:00:13 +0000 (GMT) +X-Greylist: delayed 00:15:50.393567 by SQLgrey- +Received: from cassarossa.samfundet.no (cassarossa.samfundet.no + [129.241.93.19]) + by svr1.postgresql.org (Postfix) with ESMTP id 0E6B6D9965 + for ; + Wed, 9 Nov 2005 09:00:15 -0400 (AST) +Received: from trofast.sesse.net ([129.241.93.32]) + by cassarossa.samfundet.no with esmtp (Exim 4.50) + id 1EZpYj-0003oo-65; Wed, 09 Nov 2005 14:00:18 +0100 +Received: from sesse by trofast.sesse.net with local (Exim 3.36 #1 (Debian)) + id 1EZpYn-0002PM-00; Wed, 09 Nov 2005 14:00:17 +0100 +Date: Wed, 9 Nov 2005 14:00:17 +0100 +From: "Steinar H. Gunderson" +To: Jan Kesten +Cc: pgsql-performance@postgresql.org +Subject: Re: Improving performance on multicolumn query +Message-ID: <20051109130017.GA9229@uio.no> +Mail-Followup-To: Jan Kesten , + pgsql-performance@postgresql.org +References: <4371E6A7.50808@web.de> +MIME-Version: 1.0 +Content-Type: text/plain; charset=utf-8 +Content-Disposition: inline +In-Reply-To: <4371E6A7.50808@web.de> +X-Operating-System: Linux 2.6.14 on a i686 +X-Message-Flag: Outlook? --> http://www.mozilla.org/products/thunderbird/ +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.009 required=5 tests=[AWL=0.009] +X-Spam-Score: 0.009 +X-Spam-Level: +X-Archive-Number: 200511/155 +X-Sequence-Number: 15412 + +On Wed, Nov 09, 2005 at 01:08:07PM +0100, Jan Kesten wrote: +> First, I'm using postgresql 7.4.7 on a 2GHz machine having 1.5GByte RAM +> and I have a table with about 220 columns and 20000 rows - and the first +> five columns build a primary key (and a unique index). + +I forgot this, but it should be mentioned: A primary key works as an +unique index, so you don't need both. + +/* Steinar */ +-- +Homepage: http://www.sesse.net/ + +From pgsql-performance-owner@postgresql.org Wed Nov 9 09:19:39 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 7957FD964B + for ; + Wed, 9 Nov 2005 09:19:37 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 36670-03 + for ; + Wed, 9 Nov 2005 13:19:33 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 80650D95C1 + for ; + Wed, 9 Nov 2005 09:19:35 -0400 (AST) +Received: from vscan01.westnet.com.au (vscan01.westnet.com.au [203.10.1.131]) + by svr2.postgresql.org (Postfix) with ESMTP id CEB4CF0BD7 + for ; + Wed, 9 Nov 2005 13:19:38 +0000 (GMT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by localhost (Postfix) with ESMTP id 4E824760373; + Wed, 9 Nov 2005 21:19:34 +0800 (WST) +Received: from vscan01.westnet.com.au ([127.0.0.1]) + by localhost (vscan01.westnet.com.au [127.0.0.1]) (amavisd-new, + port 10024) + with ESMTP id 12370-11; Wed, 9 Nov 2005 21:19:34 +0800 (WST) +Received: from [202.72.133.22] (dsl-202-72-133-22.wa.westnet.com.au + [202.72.133.22]) + by vscan01.westnet.com.au (Postfix) with ESMTP id C32C576035D; + Wed, 9 Nov 2005 21:19:33 +0800 (WST) +Message-ID: <4371F765.1050209@familyhealth.com.au> +Date: Wed, 09 Nov 2005 21:19:33 +0800 +From: Christopher Kings-Lynne +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Jan Kesten +Cc: pgsql-performance@postgresql.org +Subject: Re: Improving performance on multicolumn query +References: <4371E6A7.50808@web.de> +In-Reply-To: <4371E6A7.50808@web.de> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.011 required=5 tests=[AWL=0.011] +X-Spam-Score: 0.011 +X-Spam-Level: +X-Archive-Number: 200511/156 +X-Sequence-Number: 15413 + +> transfer=> explain analyse SELECT * FROM test WHERE test_a=9091150001 +> AND test_b=1 AND test_c=2 AND test_d=0 AND test_e=0; +> +> Index Scan using test_idx on test (cost=0.00..50.27 rows=1 width=1891) +> (actual time=0.161..0.167 rows=1 loops=1) +> Index Cond: (test_a = 9091150001::bigint) +> Filter: ((test_b = 1) AND (test_c = 2) AND (test_d = 0) AND (test_e 0)) +> +> So, what to do to speed things up? If I understand correctly this +> output, the planner uses my index (test_idx is the same as test_pkey +> created along with the table), but only for the first column. + +Hi Jan, + +If you're using 7.4.x then the planner can't use the index for unquoted +bigints. Try this: + +SELECT * FROM test WHERE test_a='9091150001' AND test_b='1' AND +test_c=''2 AND test_d='0' AND test_e='0'; + +Chris + +From pgsql-performance-owner@postgresql.org Wed Nov 9 13:13:57 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A0EA0D7D42 + for ; + Wed, 9 Nov 2005 13:13:56 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 05151-04 + for ; + Wed, 9 Nov 2005 17:13:55 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (floppy.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 924B4D79D9 + for ; + Wed, 9 Nov 2005 13:13:54 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id B324931058; Wed, 9 Nov 2005 18:13:51 +0100 (MET) +From: Charlie Savage +X-Newsgroups: pgsql.performance +Subject: Re: Sort performance on large tables +Date: Wed, 09 Nov 2005 10:13:46 -0700 +Organization: Hub.Org Networking Services +Lines: 29 +Message-ID: <43722E4A.8060904@interserv.com> +References: <43704E1D.80708@interserv.com> + <1131528955.8300.2101.camel@localhost.localdomain> +Mime-Version: 1.0 +Content-Type: text/plain; charset=UTF-8; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +To: Simon Riggs +User-Agent: Thunderbird 1.5 (Windows/20051025) +In-Reply-To: <1131528955.8300.2101.camel@localhost.localdomain> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/158 +X-Sequence-Number: 15415 + +Hi Simon, + +Thanks for the response Simon. + +> PostgreSQL can do HashAggregates as well as GroupAggregates, just like +> Oracle. HashAggs avoid the sort phase, so would improve performance +> considerably. The difference in performance you are getting is because +> of the different plan used. Did you specifically do anything to Oracle +> to help it get that plan, or was it a pure out-of-the-box install (or +> maybe even a "set this up for Data Warehousing" install)? + +It was an out-of-the-box plan with the standard database install option +(wasn't a Data Warehousing install). + +> Can you let us know how high you have to set work_mem before an EXPLAIN +> (not EXPLAIN ANALYZE) chooses the HashAgg plan? + +The planner picked a HashAggregate only when I set work_mem to 2097151 - +which I gather is the maximum allowed value according to a message +returned from the server. + + +> Please be aware that publishing Oracle performance results is against +> the terms of their licence and we seek to be both fair and legitimate, +> especially within this public discussion forum. + +Sorry, I didn't realize - I'll be more vague next time. + +Charlie + +From pgsql-performance-owner@postgresql.org Wed Nov 9 13:31:45 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 28429D70C0 + for ; + Wed, 9 Nov 2005 13:31:43 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 07795-06 + for ; + Wed, 9 Nov 2005 17:31:41 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from h6608.serverkompetenz.net (gpg-keyserver.de [81.169.179.29]) + by svr1.postgresql.org (Postfix) with ESMTP id 7D7F5D6FCC + for ; + Wed, 9 Nov 2005 13:31:41 -0400 (AST) +Received: from brs9-d9bad87e.pool.mediaways.net ([217.186.216.126] + helo=[192.168.0.51]) + by h6608.serverkompetenz.net with asmtp (Exim 4.34) + id 1EZtnP-0003bi-Kc + for pgsql-performance@postgresql.org; Wed, 09 Nov 2005 18:31:39 +0100 +Message-ID: <43723257.5060804@web.de> +Date: Wed, 09 Nov 2005 18:31:03 +0100 +From: Jan Kesten +User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: Improving performance on multicolumn query +References: <4371E6A7.50808@web.de> <20051109124429.GA9127@uio.no> +In-Reply-To: <20051109124429.GA9127@uio.no> +X-Enigmail-Version: 0.92.0.0 +OpenPGP: id=82201FC4; + url=http://gpg-keyserver.de +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/159 +X-Sequence-Number: 15416 + +Hi all! + +First thanks to any answer by now :-) + +> You don't post your table definitions (please do), but it looks like +> test_b, test_c, test_d and test_e might be bigints? If so, you may +> want to do explicit "AND test_b=1::bigint AND test_c=2::bigint" etc. +> -- 7.4 doesn't figure this out for you. (8.0 and higher does.) + +I didn't post table defintion, but you all are right, test_a to test_e +are all bigint. I use JDBC to connect to this database and use a +prepared statment for the queries and set all parameters with +pst.setLong() method. Perhaps this could be the problem? I'll try +'normal' statements with typecasting, because as far as I can see, the +query is the problem (postgresql takes more than 98% cpu while running +these statements) or the overhead produced (but not the network, as it +has only 1-2% load). Quering other tables (not as big - both rows and +columns are much less) run quite fast with the same code. + +So, thanks again - I'll try and report :-) Can't be so slow, I have some +self-build database with millions of rows and they run very fast - but +they don't use bigint ;-) + +Cheers, +Jan + +From pgsql-performance-owner@postgresql.org Wed Nov 9 17:41:25 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A355EDA4D7 + for ; + Wed, 9 Nov 2005 17:41:22 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 00578-08 + for ; + Wed, 9 Nov 2005 21:41:00 +0000 (GMT) +X-Greylist: delayed 03:14:41.359269 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 3179ADAAB3 + for ; + Wed, 9 Nov 2005 17:40:48 -0400 (AST) +Received: from pop-tawny.atl.sa.earthlink.net (pop-tawny.atl.sa.earthlink.net + [207.69.195.67]) + by svr2.postgresql.org (Postfix) with ESMTP id 87782F1098 + for ; + Wed, 9 Nov 2005 18:26:17 +0000 (GMT) +Received: from elwamui-hound.atl.sa.earthlink.net ([209.86.224.34]) + by pop-tawny.atl.sa.earthlink.net with esmtp (Exim 3.36 #10) + id 1EZueD-0001ge-00; Wed, 09 Nov 2005 13:26:13 -0500 +Message-ID: + <11779240.1131560773750.JavaMail.root@elwamui-hound.atl.sa.earthlink.net> +Date: Wed, 9 Nov 2005 13:26:13 -0500 (EST) +From: Ron Peacetree +Reply-To: Ron Peacetree +To: Charlie Savage , + pgsql-performance@postgresql.org +Subject: Re: Sort performance on large tables +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Mailer: EarthLink Zoo Mail 1.0 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.311 required=5 tests=[AWL=-0.168, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.311 +X-Spam-Level: +X-Archive-Number: 200511/164 +X-Sequence-Number: 15421 + +...and on those notes, let me repeat my often stated advice that a DB server should be configured with as much RAM as is feasible. 4GB or more strongly recommended. + +I'll add that the HW you are using for a DB server should be able to hold _at least_ 4GB of RAM (note that modern _laptops_ can hold 2GB. Next year's are likely to be able to hold 4GB.). I can't casually find specs on the D3000, but if it can't be upgraded to at least 4GB, you should be looking for new DB server HW. + +At this writing, 4 1GB DIMMs (4GB) should set you back ~$300 or less. 4 2GB DIMMs (8GB) should cost ~$600. +As of now, very few mainboards support 4GB DIMMs and I doubt the D3000 has such a mainboard. If you can use them, 4 4GB DIMMs (16GB) will currently set you back ~$1600-$2400. + +Whatever the way you do it, it's well worth the money to have at least 4GB of RAM in a DB server. It makes all kinds of problems just not exist. + +Ron + + +-----Original Message----- +From: Simon Riggs +Sent: Nov 9, 2005 4:35 AM +To: Charlie Savage , Luke Lonergan +Cc: pgsql-performance@postgresql.org +Subject: Re: [PERFORM] Sort performance on large tables + +On Tue, 2005-11-08 at 00:05 -0700, Charlie Savage wrote: + +> Setup: Dell Dimension 3000, Suse 10, 1GB ram, PostgreSQL 8.1 RC 1 with + +> I want to extract data out of the file, with the most important values +> being stored in a column called tlid. The tlid field is an integer, and +> the values are 98% unique. There is a second column called ogc_fid +> which is unique (it is a serial field). I need to extract out unique +> TLID's (doesn't matter which duplicate I get rid of). To do this I am +> running this query: +> +> SELECT tlid, min(ogc_fid) +> FROM completechain +> GROUP BY tlid; +> +> The results from explain analyze are: +> +> "GroupAggregate (cost=10400373.80..11361807.88 rows=48071704 width=8) +> (actual time=7311682.715..8315746.835 rows=47599910 loops=1)" +> " -> Sort (cost=10400373.80..10520553.06 rows=48071704 width=8) +> (actual time=7311682.682..7972304.777 rows=48199165 loops=1)" +> " Sort Key: tlid" +> " -> Seq Scan on completechain (cost=0.00..2228584.04 +> rows=48071704 width=8) (actual time=27.514..773245.046 rows=48199165 +> loops=1)" +> "Total runtime: 8486057.185 ms" + +> Should I expect results like this? I realize that the computer is quite +> low-end and is very IO bound for this query, but I'm still surprised +> that the sort operation takes so long. +> +> Out of curiosity, I setup an Oracle database on the same machine with +> the same data and ran the same query. Oracle was over an order of +> magnitude faster. Looking at its query plan, it avoided the sort by +> using "HASH GROUP BY." Does such a construct exist in PostgreSQL (I see +> only hash joins)? + +PostgreSQL can do HashAggregates as well as GroupAggregates, just like +Oracle. HashAggs avoid the sort phase, so would improve performance +considerably. The difference in performance you are getting is because +of the different plan used. Did you specifically do anything to Oracle +to help it get that plan, or was it a pure out-of-the-box install (or +maybe even a "set this up for Data Warehousing" install)? + +To get a HashAgg plan, you need to be able to fit all of the unique +values in memory. That would be 98% of 48071704 rows, each 8+ bytes +wide, giving a HashAgg memory sizing of over 375MB. You must allocate +memory of the next power of two above the level you want, so we would +need to allocate 512MB to work_mem before it would consider using a +HashAgg. + +Can you let us know how high you have to set work_mem before an EXPLAIN +(not EXPLAIN ANALYZE) chooses the HashAgg plan? + +Please be aware that publishing Oracle performance results is against +the terms of their licence and we seek to be both fair and legitimate, +especially within this public discussion forum. + +Best Regards, Simon Riggs + + +---------------------------(end of broadcast)--------------------------- +TIP 1: if posting/reading through Usenet, please send an appropriate + subscribe-nomail command to majordomo@postgresql.org so that your + message can get through to the mailing list cleanly + + +From pgsql-performance-owner@postgresql.org Wed Nov 9 15:59:39 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 304F3D7E67 + for ; + Wed, 9 Nov 2005 15:59:36 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 57098-02 + for ; + Wed, 9 Nov 2005 19:59:31 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from brmea-mail-3.sun.com (brmea-mail-3.Sun.COM [192.18.98.34]) + by svr1.postgresql.org (Postfix) with ESMTP id BEEB3D77CC + for ; + Wed, 9 Nov 2005 15:59:29 -0400 (AST) +Received: from phys-hanwk-1 ([129.149.2.111]) + by brmea-mail-3.sun.com (8.12.10/8.12.9) with ESMTP id jA9JxT3F024796 + for ; + Wed, 9 Nov 2005 12:59:29 -0700 (MST) +Received: from conversion-daemon.hanwk-mail1.sfbay.sun.com by + hanwk-mail1.sfbay.sun.com + (iPlanet Messaging Server 5.2 HotFix 1.24 (built Dec 19 2003)) + id <0IPP00901DT7ZB@hanwk-mail1.sfbay.sun.com> + (original mail from Ashok.Agrawal@Sun.COM) + for pgsql-performance@postgresql.org; + Wed, 09 Nov 2005 11:59:29 -0800 (PST) +Received: from Sun.COM (sr1-unwk-09.SFBay.Sun.COM [129.149.2.159]) + by hanwk-mail1.sfbay.sun.com + (iPlanet Messaging Server 5.2 HotFix 1.24 (built Dec 19 2003)) + with ESMTP id <0IPP001URE6PUK@hanwk-mail1.sfbay.sun.com> for + pgsql-performance@postgresql.org; Wed, 09 Nov 2005 11:59:13 -0800 (PST) +Date: Wed, 09 Nov 2005 11:59:13 -0800 +From: Ashok Agrawal +Subject: Outer Join performance in PostgreSQL +To: pgsql-performance@postgresql.org +Reply-To: Ashok.Agrawal@Sun.COM +Message-id: <43725511.3040809@Sun.COM> +MIME-version: 1.0 +Content-type: text/plain; charset=us-ascii +Content-transfer-encoding: 7BIT +X-Accept-Language: en-us, en +User-Agent: Mozilla/5.0 (X11; U; SunOS sun4u; en-US; rv:1.4) Gecko/20041214 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.062 required=5 tests=[AWL=0.061, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.062 +X-Spam-Level: +X-Archive-Number: 200511/160 +X-Sequence-Number: 15417 + +I noticed outer join is very very slow in postgresql as compared +to Oracle. + +SELECT a.dln_code, a.company_name, +to_char(a.certificate_date,'DD-MON-YYYY'), +to_char(a.certificate_type_id, '99'), +COALESCE(b.certificate_type_description,'None') , +a.description, a.blanket_single, a.certificate_status, +COALESCE(a.sun_legal_entity, 'None'), +COALESCE(a.other_entity_name, 'None'), +COALESCE(a.notes, 'None'),COALESCE(c.name, NULL), +COALESCE(to_char(a.created_date,'DD-MON-YYYY'), 'N/A'), +COALESCE(c.name, NULL), +COALESCE(to_char(a.updated_date,'DD-MON-YYYY'), 'N/A'), +COALESCE(e.name, NULL), +COALESCE(to_char(a.approved_date,'DD-MON-YYYY'), 'N/A') + FROM ((((ecms_cert_headers a + LEFT OUTER JOIN taxpack_user c ON (a.created_by = c.emp_no)) + LEFT OUTER JOIN taxpack_user d ON (a.updated_by = d.emp_no)) + LEFT OUTER JOIN taxpack_user e ON (a.approved_by = e.emp_no)) + INNER JOIN ecms_certificate_types b ON + (a.certificate_type_id= b.certificate_type_id )) + WHERE a.dln_code = '17319' + + +This query return only 1 record but take 25 second to execute in postgreSQL +as compared to 1.3 second in Oracle. Any suggestion ? Below is explain output. + + + Hash Join (cost=1666049.74..18486619.37 rows=157735046 width=874) + Hash Cond: ("outer".certificate_type_id = "inner".certificate_type_id) + -> Merge Right Join (cost=1666048.13..11324159.05 rows=643816513 width=826) + Merge Cond: ("outer"."?column3?" = "inner"."?column16?") + -> Sort (cost=30776.19..31207.80 rows=172645 width=64) + Sort Key: (e.emp_no)::text + -> Seq Scan on taxpack_user e (cost=0.00..4898.45 rows=172645 +width=64) + -> Sort (cost=1635271.94..1637136.51 rows=745827 width=811) + Sort Key: (a.approved_by)::text + -> Merge Left Join (cost=25230.45..36422.18 rows=745827 width=811) + Merge Cond: ("outer"."?column17?" = "inner"."?column2?") + -> Sort (cost=3117.35..3119.51 rows=864 width=844) + Sort Key: (a.updated_by)::text + -> Nested Loop Left Join (cost=0.00..3075.21 +rows=864 width=844) + -> Index Scan using pk_ecms_cert_headers on +ecms_cert_headers a (cost=0.00..6.01 rows=1 width=829) + Index Cond: ((dln_code)::text = +'17319'::text) + -> Index Scan using ash_n1 on taxpack_user c +(cost=0.00..3058.40 rows=864 width=64) + Index Cond: (("outer".created_by)::text = +(c.emp_no)::text) + -> Sort (cost=22113.10..22544.71 rows=172645 width=16) + Sort Key: (d.emp_no)::text + -> Seq Scan on taxpack_user d (cost=0.00..4898.45 +rows=172645 width=16) + -> Hash (cost=1.49..1.49 rows=49 width=50) + -> Seq Scan on ecms_certificate_types b (cost=0.00..1.49 rows=49 +width=50) +(23 rows) + +Thanks +Ashok + + +From pgsql-performance-owner@postgresql.org Wed Nov 9 16:35:31 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 80F89DA2D0 + for ; + Wed, 9 Nov 2005 16:35:26 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 72877-04 + for ; + Wed, 9 Nov 2005 20:35:22 +0000 (GMT) +X-Greylist: delayed 00:24:00.222416 by SQLgrey- +Received: from hoboe1bl1.telenet-ops.be (hoboe1bl1.telenet-ops.be + [195.130.137.72]) + by svr1.postgresql.org (Postfix) with ESMTP id 97CABDA2C7 + for ; + Wed, 9 Nov 2005 16:35:22 -0400 (AST) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by hoboe1bl1.telenet-ops.be (Postfix) with SMTP id 29042381E4 + for ; + Wed, 9 Nov 2005 21:11:19 +0100 (CET) +Received: from [10.0.1.2] (d5152B313.access.telenet.be [81.82.179.19]) + by hoboe1bl1.telenet-ops.be (Postfix) with ESMTP id C9B823805D + for ; + Wed, 9 Nov 2005 21:11:18 +0100 (CET) +Mime-Version: 1.0 (Apple Message framework v623) +To: pgsql-performance@postgresql.org +Message-Id: <717cfb0994c1b2752f7da311614e3148@implements.be> +Content-Type: multipart/mixed; boundary=Apple-Mail-38-788539305 +From: Yves Vindevogel +Subject: Some help on buffers and other performance tricks +Date: Wed, 9 Nov 2005 21:11:18 +0100 +X-Mailer: Apple Mail (2.623) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/161 +X-Sequence-Number: 15418 + + +--Apple-Mail-38-788539305 +Content-Type: multipart/alternative; + boundary=Apple-Mail-39-788539306 + + +--Apple-Mail-39-788539306 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/plain; + charset=ISO-8859-1; + format=flowed + +Hi all, + +I've got PG 8.0 on Debian sarge set up ... +I want to speed up performance on the system. + +The system will run PG, Apache front-end on port 80 and Tomcat / Cocoon=20= + +for the webapp. +The webapp is not so heavily used, so we can give the max performance=20 +to the database. +The database has a lot of work to do, we upload files every day. +The current server has 8 databases of around 1 million records. This=20 +will be more in the future. +There's only one main table, with some smaller tables. 95% of the=20 +records are in that one table. +A lot of updates are done on that table, affecting 10-20% of the=20 +records. + +The system has 1 gig of ram. I could give 512Mb to PG. +Filesystem is ext2, with the -noatime parameter in fstab + +Could I get some suggestions in how to configure my buffers, wals, ....=20= + +? + +Met vriendelijke groeten, +Bien =E0 vous, +Kind regards, + +Yves Vindevogel +Implements + + +--Apple-Mail-39-788539306 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/enriched; + charset=ISO-8859-1 + +Hi all, + + +I've got PG 8.0 on Debian sarge set up ... + +I want to speed up performance on the system. + + +The system will run PG, Apache front-end on port 80 and Tomcat / +Cocoon for the webapp. + +The webapp is not so heavily used, so we can give the max performance +to the database. + +The database has a lot of work to do, we upload files every day. + +The current server has 8 databases of around 1 million records. This +will be more in the future. + +There's only one main table, with some smaller tables. 95% of the +records are in that one table. + +A lot of updates are done on that table, affecting 10-20% of the +records. + + +The system has 1 gig of ram. I could give 512Mb to PG. + +Filesystem is ext2, with the -noatime parameter in fstab + + +Could I get some suggestions in how to configure my buffers, wals, +.... ? + + +Met vriendelijke groeten, + +Bien =E0 vous, + +Kind regards, + + +Yves Vindevogel + +Implements + + + += + +--Apple-Mail-39-788539306-- + +--Apple-Mail-38-788539305 +Content-Transfer-Encoding: base64 +Content-Type: image/tiff; + x-unix-mode=0666; + name="Pasted Graphic 2.tiff" +Content-Disposition: inline; + filename="Pasted Graphic 2.tiff" + +TU0AKgAAFciAP6BP5/wWDQeEQmFQuGQ2HQ+FP5+v9rOh5P9IMBuP8zK9tP8fJNlP8QoNjP8FndhP +8MnyVjJHSMrqFnv9BL1vP9ett2v98PuJxChUOiUWGQOCUalUujOV4PZ/qBluR/mdVtJ/jVHst/ho +9MF/g08WABHJfv8AWa0WoAHFfWuzgg6sB/hY9ysUohjv8qqVqv9LMZxv9ouV40zEYmHUjFY2HPx+ +RNtOl4Rhftt/phiRs6LC/iA5LewnJeWg46W22+02cAHOwa26bC0HPY7TZ7G2G9dv8EHFdP8Om9YP +8rKJov9UtFzv9Dzh/sRvu5/vZ9PzHdeF4zsUqgQRlOR5v9DMBwv8uqe/jZIVwNHu6B0/WAKHvWGr +RAA1ra0G1c/vfgANrdraXrTQIAA6JW2TUrQNz/ja0oAjO4YAjSWS0DOWawjys4RkIk4Lj2sAWEUZ 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+--Apple-Mail-40-788539307 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; + charset=US-ASCII; + format=flowed + + + +Mail: yves.vindevogel@implements.be - Mobile: +32 (478) 80 82 91 + +Kempische Steenweg 206 - 3500 Hasselt - Tel-Fax: +32 (11) 43 55 76 + +Web: http://www.implements.be + +First they ignore you. Then they laugh at you. Then they fight you. +Then you win. +Mahatma Ghandi. +--Apple-Mail-40-788539307 +Content-Transfer-Encoding: 7bit +Content-Type: text/enriched; + charset=US-ASCII + + + + +Mail: yves.vindevogel@implements.be - Mobile: +32 (478) 80 82 91 + + +Kempische Steenweg 206 - 3500 Hasselt - Tel-Fax: +32 (11) 43 55 76 + + +Web: http://www.implements.be + + + +First they ignore you. Then they laugh at you. Then they fight you. +Then you win. + +Mahatma Ghandi. +--Apple-Mail-40-788539307-- + +--Apple-Mail-38-788539305-- + + +From pgsql-performance-owner@postgresql.org Wed Nov 9 17:43:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0555ADA44B + for ; + Wed, 9 Nov 2005 17:41:21 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 03208-03 + for ; + Wed, 9 Nov 2005 21:41:12 +0000 (GMT) +X-Greylist: delayed 00:57:45.373243 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id E857EDAC6A + for ; + Wed, 9 Nov 2005 17:41:04 -0400 (AST) +Received: from asmail001.abovesecurity.com (asmail001.abovesecurity.com + [206.162.148.235]) + by svr2.postgresql.org (Postfix) with ESMTP id 99C4BF0C70 + for ; + Wed, 9 Nov 2005 20:43:21 +0000 (GMT) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: quoted-printable +Subject: (View and SQL) VS plpgsql +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Date: Wed, 9 Nov 2005 15:43:18 -0500 +Message-ID: +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: (View and SQL) VS plpgsql +Thread-Index: AcXlbjcI8fv5lTwCRd6ecpvDfXlSkA== +From: "Eric Lauzon" +To: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.057 required=5 tests=[AWL=0.057] +X-Spam-Score: 0.057 +X-Spam-Level: +X-Archive-Number: 200511/165 +X-Sequence-Number: 15422 + + +Hello all , i post this question here because i wasen't able to find +answer to my question elsewhere , i hope someone can answer. + + +Abstract: + +The function that can be found at the end of the e-mail emulate two = +thing. + +First it will fill a record set of result with needed column from a = +table and two "empty result column" a min and a max. + +Those two column are then filled by a second query on the same table = +that will do a min and a max + +on an index idx_utctime. + +The function loop for the first recordset and return a setof record that = +is casted by caller to the function. + + +The goald of this is to enabled the application that will receive the = +result set to minimise its + +work by having to group internaly two matching rowset. We use to handle = +two resultset but i am looking + +toward improving performances and at first glance it seem to speed up = +the process. + + +Questions: + +1. How could this be done in a single combinasion of SQL and view?=20 + +2. In a case like that is plpgsql really givig significant overhead? + +3. Performance difference [I would need a working pure-SQL version to = +compare PLANNER and Explain results ] + +STUFF: + +--TABLE && INDEX + + +CREATE TABLE archive_event +( + inst int4 NOT NULL, + cid int8 NOT NULL, + src int8 NOT NULL, + dst int8 NOT NULL, + bid int8 NOT NULL, + tid int4 NOT NULL, + utctime int4 NOT NULL, + CONSTRAINT ids_archives_event_pkey PRIMARY KEY (inst, cid), + CONSTRAINT ids_archives_event_cid_index UNIQUE (cid) +)=20 + +--index + +CREATE INDEX idx_archive_utctime + ON archive_event + USING btree + (utctime); + +CREATE INDEX idx_archive_src + ON archive_event + USING btree + (src); + +CREATE INDEX idx_archive_bid_tid + ON archive_event + USING btree + (tid, bid); + + + + +--FUNCTION +CREATE OR REPLACE FUNCTION console_get_source_rule_level_1() + RETURNS SETOF RECORD AS +' +DECLARE + +one_record record; +r_record record; + +BEGIN + + FOR r_record IN SELECT count(cid) AS hits,src, bid, tid,NULL::int8 as = +min_time,NULL::int8 as max_time FROM archive_event WHERE inst=3D\'3\' = +AND (utctime BETWEEN \'1114920000\' AND \'1131512399\') GROUP BY src, = +bid, tid LOOP + + SELECT INTO one_record MIN(utctime) as timestart,MAX(utctime) as = +timestop from archive_event where src =3Dr_record.src AND bid = +=3Dr_record.bid AND tid =3D r_record.tid AND inst =3D\'3\' AND (utctime = +BETWEEN \'1114920000\' AND \'1131512399\'); + + r_record.min_time :=3D one_record.timestart; + r_record.max_time :=3D one_record.timestop; + =20 + RETURN NEXT r_record; + +END LOOP; + + RETURN; + +END; +' + LANGUAGE 'plpgsql' VOLATILE; +GRANT EXECUTE ON FUNCTION console_get_source_rule_level_1() TO console = +WITH GRANT OPTION; + + +--FUNCTION CALLER +SELECT * from get_source_rule_level_1() AS (hits int8,src int8,bid = +int8,tid int4,min_time int8,max_time int8) + + + +Eric Lauzon +[Recherche & D=E9veloppement] +Above S=E9curit=E9 / Above Security +T=E9l : (450) 430-8166 +Fax : (450) 430-1858=20 + +From pgsql-performance-owner@postgresql.org Wed Nov 9 17:40:34 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 362ADDA52E + for ; + Wed, 9 Nov 2005 17:40:33 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 00593-05 + for ; + Wed, 9 Nov 2005 21:40:27 +0000 (GMT) +X-Greylist: delayed 00:54:36.928463 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 1CBDDDA245 + for ; + Wed, 9 Nov 2005 17:40:27 -0400 (AST) +Received: from william.ironicdesign.com (william.ironicdesign.com + [216.180.99.12]) + by svr2.postgresql.org (Postfix) with ESMTP id 1E844F1238 + for ; + Wed, 9 Nov 2005 20:45:51 +0000 (GMT) +Received: from hero.mallet-assembly.org (user-10lf9os.cable.mindspring.com + [65.87.167.28]) + by william.ironicdesign.com (Postfix) with ESMTP id 2B2FF46006D + for ; + Wed, 9 Nov 2005 14:45:46 -0600 (CST) +From: Michael Alan Dorman +To: pgsql-performance@postgresql.org +Subject: Re: Outer Join performance in PostgreSQL +References: <43725511.3040809@Sun.COM> +Mail-Followup-To: pgsql-performance@postgresql.org +Date: Wed, 09 Nov 2005 15:45:53 -0500 +In-Reply-To: <43725511.3040809@Sun.COM> (Ashok Agrawal's message of "Wed, 09 + Nov 2005 11:59:13 -0800") +Message-ID: <87d5l9r1mm.fsf@hero.mallet-assembly.org> +User-Agent: Gnus/5.110004 (No Gnus v0.4) Emacs/22.0.50 (gnu/linux) +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/163 +X-Sequence-Number: 15420 + +Ashok Agrawal writes: +> I noticed outer join is very very slow in postgresql as compared +> to Oracle. + +I think the three things the people best able to help you are going to +ask for are 1) what version of PostgreSQL, 2) what are the tables, and +how many rows in each, and 3) output from 'explain analyze' rather +than just 'explain'. + +That said, I'm willing to take an amateurish stab at it even without +that. + +In fact, I don't think the outer joins are the issue at all. I see +that you're forcing a right join from ecms_certificate_types to +ecms_cert_headers. This seems to be causing postgresql to think it +must (unnecessarily) consider three quarters of a billion rows, which, +if I'm reading right, seems to be producing the majority of the +estimated cost: + +> Hash Join (cost=1666049.74..18486619.37 rows=157735046 width=874) +> Hash Cond: ("outer".certificate_type_id = "inner".certificate_type_id) +> -> Merge Right Join (cost=1666048.13..11324159.05 rows=643816513 width=826) + +In fact, looking at the fact that you're doing a COALESCE on a column +from b, it seems to me that doing a right join from ecms_cert_headers +to ecms_certificate_types is just wrong. It seems to me that that +should be a left join as well. + +With that in mind, I would rewrite the whole FROM clause as: + + FROM ecms_cert_headers a +LEFT OUTER JOIN ecms_certificate_types b + ON (a.certificate_type_id = b.certificate_type_id) +LEFT OUTER JOIN taxpack_user c + ON (a.created_by = c.emp_no) +LEFT OUTER JOIN taxpack_user d + ON (a.updated_by = d.emp_no) +LEFT OUTER JOIN taxpack_user e + ON (a.approved_by = e.emp_no) + WHERE a.dln_code = '17319' + +It seems to me that this more reflects the intent of the data that is +being retrieved. I would also expect it to be a boatload faster. + +Assuming I've understood the intent correctly, I would guess that the +difference is the result of the Oracle planner being able to eliminate +the right join or something. + +Mike + +From pgsql-performance-owner@postgresql.org Wed Nov 9 17:24:55 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 73160D9DE0 + for ; + Wed, 9 Nov 2005 17:24:54 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 93400-09 + for ; + Wed, 9 Nov 2005 21:24:49 +0000 (GMT) +X-Greylist: delayed 02:58:33.844077 by SQLgrey- +Received: from pop-tawny.atl.sa.earthlink.net (pop-tawny.atl.sa.earthlink.net + [207.69.195.67]) + by svr1.postgresql.org (Postfix) with ESMTP id 8D13CD9AE8 + for ; + Wed, 9 Nov 2005 17:24:49 -0400 (AST) +Received: from elwamui-hound.atl.sa.earthlink.net ([209.86.224.34]) + by pop-tawny.atl.sa.earthlink.net with esmtp (Exim 3.36 #10) + id 1EZxR3-0005bY-00; Wed, 09 Nov 2005 16:24:49 -0500 +Message-ID: + <17035565.1131571489652.JavaMail.root@elwamui-hound.atl.sa.earthlink.net> +Date: Wed, 9 Nov 2005 16:24:49 -0500 (EST) +From: Ron Peacetree +Reply-To: Ron Peacetree +To: Yves Vindevogel , + pgsql-performance@postgresql.org +Subject: Re: Some help on buffers and other performance tricks +Mime-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +X-Mailer: EarthLink Zoo Mail 1.0 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.31 required=5 tests=[AWL=-0.169, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.31 +X-Spam-Level: +X-Archive-Number: 200511/162 +X-Sequence-Number: 15419 + +0=3D Optimize your schema to be a tight as possible. Your goal is to give = +yourself the maximum chance that everything you want to work on is in RAM w= +hen you need it. +1=3D Upgrade your RAM to as much as you can possibly strain to afford. 4GB= + at least. It's that important. +2=3D If the _entire_ DB does not fit in RAM after upgrading your RAM, the n= +ext step is making sure your HD IO subsystem is adequate to your needs. +3=3D Read the various pg tuning docs that are available and Do The Right Th= +ing. +4=3D If performance is still not acceptable, then it's time to drill down i= +nto what specific actions/queries are problems. +If you get to here and the entire DBMS is still not close to acceptable, yo= +ur fundamental assumptions have to be re-examined. + +Ron + +-----Original Message----- +From: Yves Vindevogel +Sent: Nov 9, 2005 3:11 PM +To: pgsql-performance@postgresql.org +Subject: [PERFORM] Some help on buffers and other performance tricks + +Hi all, + +I've got PG 8.0 on Debian sarge set up ... +I want to speed up performance on the system. + +The system will run PG, Apache front-end on port 80 and Tomcat / Cocoon=20 +for the webapp. +The webapp is not so heavily used, so we can give the max performance=20 +to the database. +The database has a lot of work to do, we upload files every day. +The current server has 8 databases of around 1 million records. This=20 +will be more in the future. +There's only one main table, with some smaller tables. 95% of the=20 +records are in that one table. +A lot of updates are done on that table, affecting 10-20% of the=20 +records. + +The system has 1 gig of ram. I could give 512Mb to PG. +Filesystem is ext2, with the -noatime parameter in fstab + +Could I get some suggestions in how to configure my buffers, wals, ....=20 +? + +Met vriendelijke groeten, +Bien =EF=BF=BD vous, +Kind regards, + +Yves Vindevogel +Implements + + + +From pgsql-performance-owner@postgresql.org Wed Nov 9 18:47:22 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8410AD9AE8 + for ; + Wed, 9 Nov 2005 18:47:21 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 20349-09 + for ; + Wed, 9 Nov 2005 22:47:18 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from megazone.bigpanda.com (megazone.bigpanda.com [64.147.171.210]) + by svr1.postgresql.org (Postfix) with ESMTP id 55524D98B8 + for ; + Wed, 9 Nov 2005 18:47:20 -0400 (AST) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id AA18235512; Wed, 9 Nov 2005 14:47:22 -0800 (PST) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id A87853550F; Wed, 9 Nov 2005 14:47:22 -0800 (PST) +Date: Wed, 9 Nov 2005 14:47:22 -0800 (PST) +From: Stephan Szabo +To: Ashok Agrawal +Cc: pgsql-performance@postgresql.org +Subject: Re: Outer Join performance in PostgreSQL +In-Reply-To: <43725511.3040809@Sun.COM> +Message-ID: <20051109144311.B34905@megazone.bigpanda.com> +References: <43725511.3040809@Sun.COM> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/166 +X-Sequence-Number: 15423 + +On Wed, 9 Nov 2005, Ashok Agrawal wrote: + +> I noticed outer join is very very slow in postgresql as compared +> to Oracle. +> +> SELECT a.dln_code, a.company_name, +> to_char(a.certificate_date,'DD-MON-YYYY'), +> to_char(a.certificate_type_id, '99'), +> COALESCE(b.certificate_type_description,'None') , +> a.description, a.blanket_single, a.certificate_status, +> COALESCE(a.sun_legal_entity, 'None'), +> COALESCE(a.other_entity_name, 'None'), +> COALESCE(a.notes, 'None'),COALESCE(c.name, NULL), +> COALESCE(to_char(a.created_date,'DD-MON-YYYY'), 'N/A'), +> COALESCE(c.name, NULL), +> COALESCE(to_char(a.updated_date,'DD-MON-YYYY'), 'N/A'), +> COALESCE(e.name, NULL), +> COALESCE(to_char(a.approved_date,'DD-MON-YYYY'), 'N/A') +> FROM ((((ecms_cert_headers a +> LEFT OUTER JOIN taxpack_user c ON (a.created_by = c.emp_no)) +> LEFT OUTER JOIN taxpack_user d ON (a.updated_by = d.emp_no)) +> LEFT OUTER JOIN taxpack_user e ON (a.approved_by = e.emp_no)) +> INNER JOIN ecms_certificate_types b ON +> (a.certificate_type_id= b.certificate_type_id )) +> WHERE a.dln_code = '17319' + +I think in the above it's safe to do the inner join first, although +PostgreSQL won't determine that currently and that could have something to +do with the difference in performance if Oracle did reorder the joins. +If you were to run the query doing the INNER JOIN first, does that give +the correct results and run more quickly in PostgreSQL? In either case, +explain analyze output would be handy to find the actual times taken by +the steps. + +From pgsql-performance-owner@postgresql.org Wed Nov 9 19:08:11 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8F46CDA282 + for ; + Wed, 9 Nov 2005 19:08:08 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 25750-04 + for ; + Wed, 9 Nov 2005 23:08:02 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mx1.surnet.cl (mx1.surnet.cl [216.155.73.180]) + by svr1.postgresql.org (Postfix) with ESMTP id DA6B3DA20D + for ; + Wed, 9 Nov 2005 19:08:01 -0400 (AST) +Received: from unknown (HELO cluster.surnet.cl) ([216.155.73.165]) + by mx1.surnet.cl with ESMTP; 09 Nov 2005 20:10:03 -0300 +X-IronPort-AV: i="3.97,310,1125892800"; + d="scan'208"; a="24327048:sNHT10221403366" +Received: from alvh.no-ip.org (216.155.78.23) by cluster.surnet.cl (7.0.043) + (authenticated as alvherre@surnet.cl) + id 4350159700348836; Wed, 9 Nov 2005 20:07:40 -0300 +Received: by alvh.no-ip.org (Postfix, from userid 1000) + id 84F4AC2D450; Wed, 9 Nov 2005 20:07:52 -0300 (CLST) +Date: Wed, 9 Nov 2005 20:07:52 -0300 +From: Alvaro Herrera +To: Ron Peacetree +Cc: Yves Vindevogel , + pgsql-performance@postgresql.org +Subject: Re: Some help on buffers and other performance tricks +Message-ID: <20051109230752.GC8230@surnet.cl> +Mail-Followup-To: Ron Peacetree , + Yves Vindevogel , + pgsql-performance@postgresql.org +References: + <17035565.1131571489652.JavaMail.root@elwamui-hound.atl.sa.earthlink.net> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: + <17035565.1131571489652.JavaMail.root@elwamui-hound.atl.sa.earthlink.net> +User-Agent: Mutt/1.5.10i +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.881 required=5 tests=[AWL=-0.364, + DNS_FROM_RFC_ABUSE=0.479, DNS_FROM_RFC_POST=1.44, + RCVD_IN_NJABL_PROXY=0.327] +X-Spam-Score: 1.881 +X-Spam-Level: * +X-Archive-Number: 200511/167 +X-Sequence-Number: 15424 + +Ron Peacetree wrote: +> 0= Optimize your schema to be a tight as possible. Your goal is to give yourself the maximum chance that everything you want to work on is in RAM when you need it. +> 1= Upgrade your RAM to as much as you can possibly strain to afford. 4GB at least. It's that important. +> 2= If the _entire_ DB does not fit in RAM after upgrading your RAM, the next step is making sure your HD IO subsystem is adequate to your needs. +> 3= Read the various pg tuning docs that are available and Do The Right Thing. +> 4= If performance is still not acceptable, then it's time to drill down into what specific actions/queries are problems. +> If you get to here and the entire DBMS is still not close to acceptable, your fundamental assumptions have to be re-examined. + +IMHO you should really be examining your queries _before_ you do any +investment in hardware, because later those may prove unnecessary. + +-- +Alvaro Herrera http://www.CommandPrompt.com/ +The PostgreSQL Company - Command Prompt, Inc. + +From pgsql-performance-owner@postgresql.org Wed Nov 9 22:58:29 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B2E62DAAA7 + for ; + Wed, 9 Nov 2005 22:58:26 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 96737-01 + for ; + Thu, 10 Nov 2005 02:58:22 +0000 (GMT) +X-Greylist: delayed 03:05:01.144894 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id E6257DA932 + for ; + Wed, 9 Nov 2005 22:58:23 -0400 (AST) +Received: from frank.wiles.org (frank.wiles.org [24.124.39.75]) + by svr2.postgresql.org (Postfix) with ESMTP id ECE64F12C0 + for ; + Wed, 9 Nov 2005 23:53:24 +0000 (GMT) +Received: from kungfu (frank.wiles.org [127.0.0.1]) + by frank.wiles.org (8.13.1/8.13.1) with SMTP id jA9NrFN3006953; + Wed, 9 Nov 2005 17:53:15 -0600 +Date: Wed, 9 Nov 2005 17:53:32 -0600 +From: Frank Wiles +To: Alvaro Herrera +Cc: rjpeace@earthlink.net, yves.vindevogel@implements.be, + pgsql-performance@postgresql.org +Subject: Re: Some help on buffers and other performance tricks +Message-Id: <20051109175332.3edbd5fc.frank@wiles.org> +In-Reply-To: <20051109230752.GC8230@surnet.cl> +References: + <17035565.1131571489652.JavaMail.root@elwamui-hound.atl.sa.earthlink.net> + <20051109230752.GC8230@surnet.cl> +X-Mailer: Sylpheed version 2.0.1 (GTK+ 2.6.10; i686-pc-linux-gnu) +Mime-Version: 1.0 +Content-Type: text/plain; charset=US-ASCII +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.016 required=5 tests=[AWL=0.016] +X-Spam-Score: 0.016 +X-Spam-Level: +X-Archive-Number: 200511/170 +X-Sequence-Number: 15427 + +On Wed, 9 Nov 2005 20:07:52 -0300 +Alvaro Herrera wrote: + +> IMHO you should really be examining your queries _before_ you do any +> investment in hardware, because later those may prove unnecessary. + + It all really depends on what you're doing. For some of the systems + I run, 4 GBs of RAM is *WAY* overkill, RAID 1+0 is overkill, etc. + + In general I would slightly change the "order of operations" from: + + 1) Buy tons of RAM + 2) Buy lots of disk I/O + 3) Tune your conf + 4) Examine your queries + + to + + 1) Tune your conf + 2) Spend a few minutes examining your queries + 3) Buy as much RAM as you can afford + 4) Buy as much disk I/O as you can + 5) Do in depth tuning of your queries/conf + + Personally I avoid planning my schema around my performance at + the start. I just try to represent the data in a sensible, + normalized way. While I'm sure I sub-consciously make decisions + based on performance considerations early on, I don't do any major + schema overhauls until I find I can't get the performance I need + via tuning. + + Obviously there are systems/datasets/quantities where this won't + always work out best, but for the majority of systems out there + complicating your schema, maxing your hardware, and THEN tuning + is IMHO the wrong approach. + + --------------------------------- + Frank Wiles + http://www.wiles.org + --------------------------------- + + +From pgsql-performance-owner@postgresql.org Wed Nov 9 20:44:41 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8229ADA5FB + for ; + Wed, 9 Nov 2005 20:44:39 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 52845-10 + for ; + Thu, 10 Nov 2005 00:44:36 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mx1.surnet.cl (mx1.surnet.cl [216.155.73.180]) + by svr1.postgresql.org (Postfix) with ESMTP id 8AD7FDA4D7 + for ; + Wed, 9 Nov 2005 20:44:36 -0400 (AST) +Received: from unknown (HELO cluster.surnet.cl) ([216.155.73.165]) + by mx1.surnet.cl with ESMTP; 09 Nov 2005 21:45:44 -0300 +X-IronPort-AV: i="3.97,310,1125892800"; + d="scan'208"; a="24361317:sNHT146117720810" +Received: from alvh.no-ip.org (216.155.78.23) by cluster.surnet.cl (7.0.043) + (authenticated as alvherre@surnet.cl) + id 435015970034B36A; Wed, 9 Nov 2005 21:43:20 -0300 +Received: by alvh.no-ip.org (Postfix, from userid 1000) + id 20543C2D450; Wed, 9 Nov 2005 21:43:33 -0300 (CLST) +Date: Wed, 9 Nov 2005 21:43:33 -0300 +From: Alvaro Herrera +To: Frank Wiles +Cc: rjpeace@earthlink.net, yves.vindevogel@implements.be, + pgsql-performance@postgresql.org +Subject: Re: Some help on buffers and other performance tricks +Message-ID: <20051110004332.GE8230@surnet.cl> +Mail-Followup-To: Frank Wiles , + rjpeace@earthlink.net, yves.vindevogel@implements.be, + pgsql-performance@postgresql.org +References: + <17035565.1131571489652.JavaMail.root@elwamui-hound.atl.sa.earthlink.net> + <20051109230752.GC8230@surnet.cl> + <20051109175332.3edbd5fc.frank@wiles.org> +Mime-Version: 1.0 +Content-Type: text/plain; charset=iso-8859-1 +Content-Disposition: inline +Content-Transfer-Encoding: 8bit +In-Reply-To: <20051109175332.3edbd5fc.frank@wiles.org> +User-Agent: Mutt/1.5.10i +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.12 required=5 tests=[AWL=0.793, + RCVD_IN_NJABL_PROXY=0.327] +X-Spam-Score: 1.12 +X-Spam-Level: * +X-Archive-Number: 200511/168 +X-Sequence-Number: 15425 + +Frank Wiles wrote: + +> Obviously there are systems/datasets/quantities where this won't +> always work out best, but for the majority of systems out there +> complicating your schema, maxing your hardware, and THEN tuning +> is IMHO the wrong approach. + +I wasn't suggesting to complicate the schema -- I was actually thinking +in systems where some queries are not using indexes, some queries are +plain wrong, etc. Buying a very expensive RAID and then noticing that +you just needed to create an index, is going to make somebody feel at +least somewhat stupid. + +-- +Alvaro Herrera Valdivia, Chile ICBM: S 39� 49' 17.7", W 73� 14' 26.8" +Y una voz del caos me habl� y me dijo +"Sonr�e y s� feliz, podr�a ser peor". +Y sonre�. Y fui feliz. +Y fue peor. + +From pgsql-performance-owner@postgresql.org Wed Nov 9 20:54:38 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 445C9D7E67 + for ; + Wed, 9 Nov 2005 20:54:37 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 55962-10 + for ; + Thu, 10 Nov 2005 00:54:34 +0000 (GMT) +X-Greylist: delayed 01:01:16.39754 by SQLgrey- +Received: from frank.wiles.org (frank.wiles.org [24.124.39.75]) + by svr1.postgresql.org (Postfix) with ESMTP id 97385DAC10 + for ; + Wed, 9 Nov 2005 20:54:35 -0400 (AST) +Received: from kungfu (frank.wiles.org [127.0.0.1]) + by frank.wiles.org (8.13.1/8.13.1) with SMTP id jAA0sXX3007180; + Wed, 9 Nov 2005 18:54:33 -0600 +Date: Wed, 9 Nov 2005 18:54:50 -0600 +From: Frank Wiles +To: Alvaro Herrera +Cc: rjpeace@earthlink.net, yves.vindevogel@implements.be, + pgsql-performance@postgresql.org +Subject: Re: Some help on buffers and other performance tricks +Message-Id: <20051109185450.2f20275d.frank@wiles.org> +In-Reply-To: <20051110004332.GE8230@surnet.cl> +References: + <17035565.1131571489652.JavaMail.root@elwamui-hound.atl.sa.earthlink.net> + <20051109230752.GC8230@surnet.cl> + <20051109175332.3edbd5fc.frank@wiles.org> + <20051110004332.GE8230@surnet.cl> +X-Mailer: Sylpheed version 2.0.1 (GTK+ 2.6.10; i686-pc-linux-gnu) +Mime-Version: 1.0 +Content-Type: text/plain; charset=US-ASCII +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.016 required=5 tests=[AWL=0.016] +X-Spam-Score: 0.016 +X-Spam-Level: +X-Archive-Number: 200511/169 +X-Sequence-Number: 15426 + +On Wed, 9 Nov 2005 21:43:33 -0300 +Alvaro Herrera wrote: + +> Frank Wiles wrote: +> +> > Obviously there are systems/datasets/quantities where this won't +> > always work out best, but for the majority of systems out there +> > complicating your schema, maxing your hardware, and THEN tuning +> > is IMHO the wrong approach. +> +> I wasn't suggesting to complicate the schema -- I was actually +> thinking in systems where some queries are not using indexes, some +> queries are plain wrong, etc. Buying a very expensive RAID and then +> noticing that you just needed to create an index, is going to make +> somebody feel at least somewhat stupid. + + Sorry I was referring to Ron statement that the first step should + be to "Optimize your schema to be as tight as possible." + + But I agree, finding out you need an index after spending $$$ on + extra hardware would be bad. Especially if you have to explain it + to the person forking over the $$$! :) + + --------------------------------- + Frank Wiles + http://www.wiles.org + --------------------------------- + + +From pgsql-performance-owner@postgresql.org Thu Nov 10 00:20:16 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6F465DA5BE + for ; + Thu, 10 Nov 2005 00:20:15 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 25219-03 + for ; + Thu, 10 Nov 2005 04:20:12 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from pop-tawny.atl.sa.earthlink.net (pop-tawny.atl.sa.earthlink.net + [207.69.195.67]) + by svr1.postgresql.org (Postfix) with ESMTP id 18554DA4C2 + for ; + Thu, 10 Nov 2005 00:20:11 -0400 (AST) +Received: from elwamui-hound.atl.sa.earthlink.net ([209.86.224.34]) + by pop-tawny.atl.sa.earthlink.net with esmtp (Exim 3.36 #10) + id 1Ea3v0-0000nl-00; Wed, 09 Nov 2005 23:20:10 -0500 +Message-ID: + <1793468.1131596410309.JavaMail.root@elwamui-hound.atl.sa.earthlink.net> +Date: Wed, 9 Nov 2005 23:20:10 -0500 (EST) +From: Ron Peacetree +Reply-To: Ron Peacetree +To: Frank Wiles , pgsql-performance@postgresql.org +Subject: Re: Some help on buffers and other performance tricks +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Mailer: EarthLink Zoo Mail 1.0 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.312 required=5 tests=[AWL=-0.167, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.312 +X-Spam-Level: +X-Archive-Number: 200511/171 +X-Sequence-Number: 15428 + +The point Gentlemen, was that Good Architecture is King. That's what I was trying to emphasize by calling proper DB architecture step 0. All other things being equal (and they usually aren't, this sort of stuff is _very_ context dependent), the more of your critical schema that you can fit into RAM during normal operation the better. + +...and it all starts with proper DB design. Otherwise, you are quite right in stating that you risk wasting time, effort, and HW. + +Ron + + +-----Original Message----- +From: Frank Wiles +Sent: Nov 9, 2005 6:53 PM +To: Alvaro Herrera +Cc: rjpeace@earthlink.net, yves.vindevogel@implements.be, pgsql-performance@postgresql.org +Subject: Re: [PERFORM] Some help on buffers and other performance tricks + +On Wed, 9 Nov 2005 20:07:52 -0300 +Alvaro Herrera wrote: + +> IMHO you should really be examining your queries _before_ you do any +> investment in hardware, because later those may prove unnecessary. + + It all really depends on what you're doing. For some of the systems + I run, 4 GBs of RAM is *WAY* overkill, RAID 1+0 is overkill, etc. + + In general I would slightly change the "order of operations" from: + + 1) Buy tons of RAM + 2) Buy lots of disk I/O + 3) Tune your conf + 4) Examine your queries + + to + + 1) Tune your conf + 2) Spend a few minutes examining your queries + 3) Buy as much RAM as you can afford + 4) Buy as much disk I/O as you can + 5) Do in depth tuning of your queries/conf + + Personally I avoid planning my schema around my performance at + the start. I just try to represent the data in a sensible, + normalized way. While I'm sure I sub-consciously make decisions + based on performance considerations early on, I don't do any major + schema overhauls until I find I can't get the performance I need + via tuning. + + Obviously there are systems/datasets/quantities where this won't + always work out best, but for the majority of systems out there + complicating your schema, maxing your hardware, and THEN tuning + is IMHO the wrong approach. + + --------------------------------- + Frank Wiles + http://www.wiles.org + --------------------------------- + + +---------------------------(end of broadcast)--------------------------- +TIP 5: don't forget to increase your free space map settings + + +From pgsql-performance-owner@postgresql.org Thu Nov 10 04:50:45 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 52CCEDAA17 + for ; + Thu, 10 Nov 2005 04:50:44 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 21371-09 + for ; + Thu, 10 Nov 2005 08:50:40 +0000 (GMT) +X-Greylist: delayed 00:05:03.677166 by SQLgrey- +Received: from moutng.kundenserver.de (moutng.kundenserver.de + [212.227.126.183]) + by svr1.postgresql.org (Postfix) with ESMTP id 11F93DA747 + for ; + Thu, 10 Nov 2005 04:50:40 -0400 (AST) +Received: from p508E7143.dip.t-dialin.net [80.142.113.67] + (helo=swtexchange2.technology.de) + by mrelayeu.kundenserver.de (node=mrelayeu7) with ESMTP (Nemesis), + id 0ML2Dk-1Ea83r1Gyi-0003P7; Thu, 10 Nov 2005 09:45:35 +0100 +content-class: urn:content-classes:message +Subject: Re: (View and SQL) VS plpgsql +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: quoted-printable +Date: Thu, 10 Nov 2005 09:45:34 +0100 +X-MimeOLE: Produced By Microsoft Exchange V6.0.6556.0 +Message-ID: + <16F953410A0F1346848DCB476A989CFE01D5D2@swtexchange2.technology.de> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: (View and SQL) VS plpgsql +Thread-Index: AcXlbjcI8fv5lTwCRd6ecpvDfXlSkAAZBSFQAAAER0A= +From: =?iso-8859-1?Q?N=F6rder-Tuitje=2C_Marcus?= + +To: "Eric Lauzon" , + +X-Provags-ID: kundenserver.de abuse@kundenserver.de + login:24478085a861b01e05bdc3b8f80dc176 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.134 required=5 tests=[AWL=0.134] +X-Spam-Score: 0.134 +X-Spam-Level: +X-Archive-Number: 200511/172 +X-Sequence-Number: 15429 + + + + + + FOR r_record IN SELECT count(cid) AS hits,src, bid, tid,NULL::int8 as = +min_time,NULL::int8 as max_time FROM archive_event WHERE inst=3D\'3\' = +AND (utctime BETWEEN \'1114920000\' AND \'1131512399\') GROUP BY src, = +bid, tid LOOP + + SELECT INTO one_record MIN(utctime) as timestart,MAX(utctime) as = +timestop from archive_event where src =3Dr_record.src AND bid = +=3Dr_record.bid AND tid =3D r_record.tid AND inst =3D\'3\' AND (utctime = +BETWEEN \'1114920000\' AND \'1131512399\'); + + + +(it seems to me, that you might combine both queries) + +1. have you ever tried to select the min/max within the first stmt ? as = +i see you are reducing data in second stmt using same key as in stmt 1. +2. you are querying data using two keys (int, utctime). you may create = +a combined index speeding up your query +3. same for grouping. you are grouping over three fields. composite = +indexing may helps (8.1 supports index based grouping) + +regards, + +marcus + + + + + +-----Urspr=FCngliche Nachricht----- +Von: pgsql-performance-owner@postgresql.org +[mailto:pgsql-performance-owner@postgresql.org]Im Auftrag von Eric +Lauzon +Gesendet: Mittwoch, 9. November 2005 21:43 +An: pgsql-performance@postgresql.org +Betreff: [PERFORM] (View and SQL) VS plpgsql + + + +Hello all , i post this question here because i wasen't able to find +answer to my question elsewhere , i hope someone can answer. + + +Abstract: + +The function that can be found at the end of the e-mail emulate two = +thing. + +First it will fill a record set of result with needed column from a = +table and two "empty result column" a min and a max. + +Those two column are then filled by a second query on the same table = +that will do a min and a max + +on an index idx_utctime. + +The function loop for the first recordset and return a setof record that = +is casted by caller to the function. + + +The goald of this is to enabled the application that will receive the = +result set to minimise its + +work by having to group internaly two matching rowset. We use to handle = +two resultset but i am looking + +toward improving performances and at first glance it seem to speed up = +the process. + + +Questions: + +1. How could this be done in a single combinasion of SQL and view?=20 + +2. In a case like that is plpgsql really givig significant overhead? + +3. Performance difference [I would need a working pure-SQL version to = +compare PLANNER and Explain results ] + +STUFF: + +--TABLE && INDEX + + +CREATE TABLE archive_event +( + inst int4 NOT NULL, + cid int8 NOT NULL, + src int8 NOT NULL, + dst int8 NOT NULL, + bid int8 NOT NULL, + tid int4 NOT NULL, + utctime int4 NOT NULL, + CONSTRAINT ids_archives_event_pkey PRIMARY KEY (inst, cid), + CONSTRAINT ids_archives_event_cid_index UNIQUE (cid) +)=20 + +--index + +CREATE INDEX idx_archive_utctime + ON archive_event + USING btree + (utctime); + +CREATE INDEX idx_archive_src + ON archive_event + USING btree + (src); + +CREATE INDEX idx_archive_bid_tid + ON archive_event + USING btree + (tid, bid); + + + + +--FUNCTION +CREATE OR REPLACE FUNCTION console_get_source_rule_level_1() + RETURNS SETOF RECORD AS +' +DECLARE + +one_record record; +r_record record; + +BEGIN + + FOR r_record IN SELECT count(cid) AS hits,src, bid, tid,NULL::int8 as = +min_time,NULL::int8 as max_time FROM archive_event WHERE inst=3D\'3\' = +AND (utctime BETWEEN \'1114920000\' AND \'1131512399\') GROUP BY src, = +bid, tid LOOP + + SELECT INTO one_record MIN(utctime) as timestart,MAX(utctime) as = +timestop from archive_event where src =3Dr_record.src AND bid = +=3Dr_record.bid AND tid =3D r_record.tid AND inst =3D\'3\' AND (utctime = +BETWEEN \'1114920000\' AND \'1131512399\'); + + r_record.min_time :=3D one_record.timestart; + r_record.max_time :=3D one_record.timestop; + =20 + RETURN NEXT r_record; + +END LOOP; + + RETURN; + +END; +' + LANGUAGE 'plpgsql' VOLATILE; +GRANT EXECUTE ON FUNCTION console_get_source_rule_level_1() TO console = +WITH GRANT OPTION; + + +--FUNCTION CALLER +SELECT * from get_source_rule_level_1() AS (hits int8,src int8,bid = +int8,tid int4,min_time int8,max_time int8) + + + +Eric Lauzon +[Recherche & D=E9veloppement] +Above S=E9curit=E9 / Above Security +T=E9l : (450) 430-8166 +Fax : (450) 430-1858=20 + +---------------------------(end of broadcast)--------------------------- +TIP 4: Have you searched our list archives? + + http://archives.postgresql.org + + + +From pgsql-performance-owner@postgresql.org Thu Nov 10 09:32:48 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CCF97DAA17 + for ; + Thu, 10 Nov 2005 09:32:46 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 03285-10 + for ; + Thu, 10 Nov 2005 13:32:42 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from cassarossa.samfundet.no (cassarossa.samfundet.no + [129.241.93.19]) + by svr1.postgresql.org (Postfix) with ESMTP id 53565DA3FA + for ; + Thu, 10 Nov 2005 09:32:42 -0400 (AST) +Received: from trofast.ipv6.sesse.net ([2001:700:300:dc03:20e:cff:fe36:a766] + helo=trofast.sesse.net) + by cassarossa.samfundet.no with esmtp (Exim 4.50) id 1EaCXi-00056o-1h + for pgsql-performance@postgresql.org; Thu, 10 Nov 2005 14:32:43 +0100 +Received: from sesse by trofast.sesse.net with local (Exim 3.36 #1 (Debian)) + id 1EaCXh-00013h-00 + for ; Thu, 10 Nov 2005 14:32:41 +0100 +Date: Thu, 10 Nov 2005 14:32:41 +0100 +From: "Steinar H. Gunderson" +To: pgsql-performance@postgresql.org +Subject: WAL sync behaviour +Message-ID: <20051110133241.GA4031@uio.no> +Mail-Followup-To: pgsql-performance@postgresql.org +MIME-Version: 1.0 +Content-Type: text/plain; charset=utf-8 +Content-Disposition: inline +X-Operating-System: Linux 2.6.14 on a i686 +X-Message-Flag: Outlook? --> http://www.mozilla.org/products/thunderbird/ +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.009 required=5 tests=[AWL=0.009] +X-Spam-Score: 0.009 +X-Spam-Level: +X-Archive-Number: 200511/173 +X-Sequence-Number: 15430 + +Hi, + +We're having problems with our PostgreSQL server using forever for simple +queries, even when there's little load -- or rather, the transactions seem +to take forever to commit. We're using 8.1 (yay!) on a single Opteron, with +WAL on the system two-disk (software) RAID-1, separate from the database +four-disk RAID-10. All drives are 10000rpm SCSI disks, with write cache +turned off; we value our data :-) We're running Linux 2.6.13.4, with 64-bit +kernel but 32-bit userspace. + +The main oddity is that simple transactions take forever to execute, even on +small tables with no triggers. A COMMIT on an otherwise idle system with one +row to commit can take anything from 60-200ms to execute, which seems quite +excessive -- sometimes (and I've verified that there's not a checkpoint or +vacuum going on at that time), transactions seem to pile up and you get +behaviour like: + +LOG: duration: 836.004 ms statement: UPDATE mivu3ping SET pingtime = NOW(), ip = '129.241.93.100', hostname = 'mivu-03.samfundet.no' WHERE posid = 'mivu-03' +LOG: duration: 753.545 ms statement: UPDATE mivu3ping SET pingtime = NOW(), ip = '129.241.93.110', hostname = 'mivu-13.samfundet.no' WHERE posid = 'mivu-13' +LOG: duration: 567.914 ms statement: UPDATE mivu3ping SET pingtime = NOW(), ip = '129.241.93.109', hostname = 'mivu-12.samfundet.no' WHERE posid = 'mivu-12' +LOG: duration: 515.013 ms statement: UPDATE mivu3ping SET pingtime = NOW(), ip = '129.241.93.105', hostname = 'mivu-08.samfundet.no' WHERE posid = 'mivu-08' +LOG: duration: 427.541 ms statement: UPDATE mivu3ping SET pingtime = NOW(), ip = '129.241.93.104', hostname = 'mivu-07.samfundet.no' WHERE posid = 'mivu-07' +LOG: duration: 383.314 ms statement: UPDATE mivu3ping SET pingtime = NOW(), ip = '129.241.93.107', hostname = 'mivu-10.samfundet.no' WHERE posid = 'mivu-10' +LOG: duration: 348.965 ms statement: UPDATE mivu3ping SET pingtime = NOW(), ip = '129.241.93.103', hostname = 'mivu-06.samfundet.no' WHERE posid = 'mivu-06' +LOG: duration: 314.465 ms statement: UPDATE mivu3ping SET pingtime = NOW(), ip = '129.241.93.101', hostname = 'mivu-04.samfundet.no' WHERE posid = 'mivu-04' +LOG: duration: 824.893 ms statement: UPDATE mivu3ping SET pingtime = NOW(), ip = '129.241.93.106', hostname = 'mivu-09.samfundet.no' WHERE posid = 'mivu-09' + +Sometimes, six or seven of these transactions even seem to wait for the same +thing, reporting finishing times of something like 6, 5, 4, 3 and 2 seconds +right after each other in the log! This is not a highly loaded system, so I +don't really see why this should happen. (We had the same problems with 7.4, +but if my imagination isn't playing games on me, they seem to have become +slightly worse with 8.1.) + +strace shows that fdatasync() takes almost all that time, but when I run my own +fdatasync() test program on the same file system, I can consistently sync a +file (after an 8kB write) in about 30ms every time, so I don't really know why +this would be so much slower with PostgreSQL. We're using the cfq scheduler, +but deadline and noop give about the same results. + +Setting wal_sync_method = open_sync seems to improve the situation +dramatically on simple commits; we get down into the 10-30ms range on an idle +system. OTOH, behaviour seems to get slightly worse when there's more stuff +going on, and we still get the 300ms transactions in batches every now and +then. + +Any good ideas? + +/* Steinar */ +-- +Homepage: http://www.sesse.net/ + +From pgsql-performance-owner@postgresql.org Thu Nov 10 12:52:00 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 32A1DDB157 + for ; + Thu, 10 Nov 2005 12:51:58 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 73900-06 + for ; + Thu, 10 Nov 2005 16:51:55 +0000 (GMT) +X-Greylist: delayed 03:09:02.48297 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 9EC19DB059 + for ; + Thu, 10 Nov 2005 12:51:51 -0400 (AST) +Received: from mail2.egcrc.net (63-193-204-9.egcrc.org [63.193.204.9]) + by svr2.postgresql.org (Postfix) with ESMTP id 93C52F0BD8 + for ; + Thu, 10 Nov 2005 13:42:57 +0000 (GMT) +Received: from egcrc-ex01.egcrc.org ([172.16.1.4]) by mail2.egcrc.net with + Microsoft SMTPSVC(6.0.3790.211); Thu, 10 Nov 2005 05:42:54 -0800 +Received: from 172.16.0.166 ([172.16.0.166]) by egcrc-ex01.egcrc.org + ([172.16.1.4]) with Microsoft Exchange Server HTTP-DAV ; + Thu, 10 Nov 2005 13:42:54 +0000 +Received: from enzian by egcrc-ex01.egcrc.org; 10 Nov 2005 05:42:56 -0800 +Subject: same plan, add 1 condition, 1900x slower +From: Mitch Skinner +To: pgsql-performance@postgresql.org +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Thu, 10 Nov 2005 05:42:56 -0800 +Message-Id: <1131630176.29496.91.camel@enzian> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) +X-OriginalArrivalTime: 10 Nov 2005 13:42:54.0424 (UTC) + FILETIME=[A6E17580:01C5E5FC] +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/186 +X-Sequence-Number: 15443 + +This is with Postgres 8.0.3. Any advice is appreciated. I'm not sure +exactly what I expect, but I was hoping that if it used the +external_id_map_source_target_id index it would be faster. Mainly I was +surprised that the same plan could perform so much differently with just +an extra condition. + +I've increased the statistics target on util.external_id_map.source, but +I'm fuzzy on exactly where (what columns) the planner could use more +information. + +statgen=> explain analyze select * from subject_source; + +QUERY PLAN +------------------------------------------------------------------------------------------------------------------------------------------------------------------------ + Merge Join (cost=0.00..316.79 rows=1186 width=46) (actual +time=0.136..9.808 rows=1186 loops=1) + Merge Cond: ("outer".id = "inner".target_id) + -> Index Scan using subject_pkey on subject norm (cost=0.00..63.36 +rows=1186 width=28) (actual time=0.050..1.834 rows=1186 loops=1) + -> Index Scan using external_id_map_primary_key on external_id_map +eim (cost=0.00..2345747.01 rows=15560708 width=26) (actual +time=0.061..2.944 rows=2175 loops=1) + Total runtime: 10.745 ms +(5 rows) + +statgen=> explain analyze select * from subject_source where +source='SCH'; + +QUERY PLAN +------------------------------------------------------------------------------------------------------------------------------------------------------------------------ + Merge Join (cost=0.00..640.95 rows=1 width=46) (actual +time=0.043..21074.403 rows=1186 loops=1) + Merge Cond: ("outer".id = "inner".target_id) + -> Index Scan using subject_pkey on subject norm (cost=0.00..63.36 +rows=1186 width=28) (actual time=0.014..1.478 rows=1186 loops=1) + -> Index Scan using external_id_map_primary_key on external_id_map +eim (cost=0.00..2384648.78 rows=4150 width=26) (actual +time=0.020..21068.508 rows=1186 loops=1) + Filter: (source = 'SCH'::bpchar) + Total runtime: 21075.142 ms +(6 rows) + +statgen=> \d subject + Table "public.subject" + Column | Type | Modifiers +---------+---------+----------- + id | bigint | not null + sex | integer | + parent1 | bigint | + parent2 | bigint | +Indexes: + "subject_pkey" PRIMARY KEY, btree (id) +Foreign-key constraints: + "subject_parent1" FOREIGN KEY (parent1) REFERENCES subject(id) +DEFERRABLE INITIALLY DEFERRED + "subject_parent2" FOREIGN KEY (parent2) REFERENCES subject(id) +DEFERRABLE INITIALLY DEFERRED + "subject_id_map" FOREIGN KEY (id) REFERENCES +util.external_id_map(target_id) DEFERRABLE INITIALLY DEFERRED + +statgen=> \d subject_source + View "public.subject_source" + Column | Type | Modifiers +-----------+-----------------------+----------- + id | bigint | + sex | integer | + parent1 | bigint | + parent2 | bigint | + source | character(3) | + source_id | character varying(32) | +View definition: + SELECT norm.id, norm.sex, norm.parent1, norm.parent2, eim.source, +eim.source_id + FROM subject norm + JOIN util.external_id_map eim ON norm.id = eim.target_id; + +statgen=> \d util.external_id_map + Table "util.external_id_map" + Column | Type | Modifiers +-----------+-----------------------+----------- + source_id | character varying(32) | not null + source | character(3) | not null + target_id | bigint | not null +Indexes: + "external_id_map_primary_key" PRIMARY KEY, btree (target_id) + "external_id_map_source_source_id_unique" UNIQUE, btree (source, +source_id) + "external_id_map_source" btree (source) + "external_id_map_source_target_id" btree (source, target_id) +Foreign-key constraints: + "external_id_map_source" FOREIGN KEY (source) REFERENCES +util.source(id) + +Thanks in advance, +Mitch + +From pgsql-performance-owner@postgresql.org Thu Nov 10 10:17:01 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 245A7DA4C2 + for ; + Thu, 10 Nov 2005 10:17:00 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 18095-06 + for ; + Thu, 10 Nov 2005 14:16:56 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.metronet.co.uk (mail.metronet.co.uk [213.162.97.75]) + by svr1.postgresql.org (Postfix) with ESMTP id B8D1DD9CDC + for ; + Thu, 10 Nov 2005 10:16:58 -0400 (AST) +Received: from mainbox.archonet.com + (84-51-143-99.archon037.adsl.metronet.co.uk [84.51.143.99]) + by smtp.metronet.co.uk (MetroNet Mail) with ESMTP + id E1A7640127E; Thu, 10 Nov 2005 14:15:14 +0000 (GMT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by mainbox.archonet.com (Postfix) with ESMTP id 2402515ED9; + Thu, 10 Nov 2005 14:14:35 +0000 (GMT) +Received: from mainbox.archonet.com ([127.0.0.1]) + by localhost (mainbox [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id 30593-08; Thu, 10 Nov 2005 14:14:31 +0000 (GMT) +Received: from [192.168.1.17] (client17.office.archonet.com [192.168.1.17]) + by mainbox.archonet.com (Postfix) with ESMTP id 20FBF15ED5; + Thu, 10 Nov 2005 14:14:31 +0000 (GMT) +Message-ID: <437355C6.4030604@archonet.com> +Date: Thu, 10 Nov 2005 14:14:30 +0000 +From: Richard Huxton +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20051013) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: "Steinar H. Gunderson" +Cc: pgsql-performance@postgresql.org +Subject: Re: WAL sync behaviour +References: <20051110133241.GA4031@uio.no> +In-Reply-To: <20051110133241.GA4031@uio.no> +Content-Type: text/plain; charset=UTF-8; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.031 required=5 tests=[AWL=0.031] +X-Spam-Score: 0.031 +X-Spam-Level: +X-Archive-Number: 200511/174 +X-Sequence-Number: 15431 + +Steinar H. Gunderson wrote: +> Hi, +> +> We're having problems with our PostgreSQL server using forever for simple +> queries, even when there's little load -- or rather, the transactions seem +> to take forever to commit. We're using 8.1 (yay!) on a single Opteron, with +> WAL on the system two-disk (software) RAID-1, separate from the database +> four-disk RAID-10. All drives are 10000rpm SCSI disks, with write cache +> turned off; we value our data :-) We're running Linux 2.6.13.4, with 64-bit +> kernel but 32-bit userspace. + +You're beyond my area of expertise, but I do know that someone's going +to ask what filesystem this is (ext2/xfs/etc). And probably to see the +strace too. + +Hmm - the only things I can think to check: +Do vmstat/iostat show any unusual activity? +Are your system logs on these disks too? +Could it be the journalling on the fs clashing with the WAL? + +-- + Richard Huxton + Archonet Ltd + +From pgsql-performance-owner@postgresql.org Thu Nov 10 10:25:37 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id BD1CDDAFCE + for ; + Thu, 10 Nov 2005 10:25:36 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 22939-02 + for ; + Thu, 10 Nov 2005 14:25:32 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from cassarossa.samfundet.no (cassarossa.samfundet.no + [129.241.93.19]) + by svr1.postgresql.org (Postfix) with ESMTP id 562E3DAF90 + for ; + Thu, 10 Nov 2005 10:25:33 -0400 (AST) +Received: from trofast.sesse.net ([129.241.93.32]) + by cassarossa.samfundet.no with esmtp (Exim 4.50) id 1EaDMt-0001M1-Vc + for pgsql-performance@postgresql.org; Thu, 10 Nov 2005 15:25:37 +0100 +Received: from sesse by trofast.sesse.net with local (Exim 3.36 #1 (Debian)) + id 1EaDMt-0001Bu-00 + for ; Thu, 10 Nov 2005 15:25:35 +0100 +Date: Thu, 10 Nov 2005 15:25:35 +0100 +From: "Steinar H. Gunderson" +To: pgsql-performance@postgresql.org +Subject: Re: WAL sync behaviour +Message-ID: <20051110142535.GA4530@uio.no> +Mail-Followup-To: pgsql-performance@postgresql.org +References: <20051110133241.GA4031@uio.no> <437355C6.4030604@archonet.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=utf-8 +Content-Disposition: inline +In-Reply-To: <437355C6.4030604@archonet.com> +X-Operating-System: Linux 2.6.14 on a i686 +X-Message-Flag: Outlook? --> http://www.mozilla.org/products/thunderbird/ +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.009 required=5 tests=[AWL=0.009] +X-Spam-Score: 0.009 +X-Spam-Level: +X-Archive-Number: 200511/175 +X-Sequence-Number: 15432 + +On Thu, Nov 10, 2005 at 02:14:30PM +0000, Richard Huxton wrote: +> You're beyond my area of expertise, but I do know that someone's going +> to ask what filesystem this is (ext2/xfs/etc). + +Ah, yes, I forgot -- it's ext3. We're considering simply moving the WAL onto +a separate partition (with data=writeback and noatime) if that can help us +any. + +> And probably to see the strace too. + +The strace with wal_sync_method = fdatasync goes like this (I attach just +before I do the commit): + +cirkus:~> sudo strace -T -p 15718 +Process 15718 attached - interrupt to quit +read(8, "\27\3\1\0 ", 5) = 5 <2.635856> +read(8, "\336\333\24KB\325Ga\324\264[\307v\254h\254\350\20\220a"..., 32) = 32 <0.000031> +read(8, "\27\3\1\0000", 5) = 5 <0.000027> +read(8, "$E\217 +send(7, "\3\0\0\0\30\0\0\0\20\0\0\0f=\0\0commit;\0", 24, 0) = 24 <0.000071> +gettimeofday({1131632603, 187599}, NULL) = 0 <0.000026> +time(NULL) = 1131632603 <0.000027> +open("pg_xlog/0000000100000000000000A2", O_RDWR|O_LARGEFILE) = 14 <0.000039> +_llseek(14, 12500992, [12500992], SEEK_SET) = 0 <0.000026> +write(14, "]\320\1\0\1\0\0\0\0\0\0\0\0\300\276\242\362\0\0\0\31\0"..., 8192) = 8192 <0.000057> +fdatasync(14) = 0 <0.260194> +gettimeofday({1131632603, 448459}, NULL) = 0 <0.000034> +time(NULL) = 1131632603 <0.000027> +time([1131632603]) = 1131632603 <0.000025> +getpid() = 15718 <0.000025> +rt_sigaction(SIGPIPE, {0x558a27e0, [], 0}, {SIG_IGN}, 8) = 0 <0.000029> +send(3, "<134>Nov 10 15:23:23 postgres[15"..., 121, 0) = 121 <0.000032> +rt_sigaction(SIGPIPE, {SIG_IGN}, NULL, 8) = 0 <0.000029> +send(7, "\4\0\0\0\330\3\0\0\20\0\0\0f=\0\0\247@\0\0\16\0\0\0\1\0"..., 984, 0) = 984 <0.000076> +send(7, "\4\0\0\0\330\3\0\0\20\0\0\0f=\0\0\247@\0\0\16\0\0\0\0\0"..., 984, 0) = 984 <0.000051> +send(7, "\4\0\0\0\330\3\0\0\20\0\0\0f=\0\0\247@\0\0\16\0\0\0\0\0"..., 984, 0) = 984 <0.000050> +send(7, "\4\0\0\0\250\0\0\0\20\0\0\0f=\0\0\247@\0\0\2\0\0\0\0\0"..., 168, 0) = 168 <0.000050> +send(7, "\4\0\0\0\250\0\0\0\20\0\0\0f=\0\0\0\0\0\0\2\0\0\0\0\0\0"..., 168, 0) = 168 <0.000049> +send(7, "\3\0\0\0\27\0\0\0\20\0\0\0f=\0\0\0", 23, 0) = 23 <0.000047> +write(8, "\27\3\1\0 B\260\253rq)\232\265o\225\272\235\v\375\31\323"..., 90) = 90 <0.000229> +read(8, +Process 15718 detached + +> Do vmstat/iostat show any unusual activity? + +No, there's not much activity. In fact, it's close to idle. + +> Are your system logs on these disks too? + +Yes, they are, but nothing much is logged, really -- and sync is off for most +of the logs in syslogd. + +> Could it be the journalling on the fs clashing with the WAL? + +Unsure -- that's what I was hoping to get some information on :-) + +/* Steinar */ +-- +Homepage: http://www.sesse.net/ + +From pgsql-performance-owner@postgresql.org Thu Nov 10 11:43:16 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 64853D8BF3 + for ; + Thu, 10 Nov 2005 11:43:14 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 52260-06 + for ; + Thu, 10 Nov 2005 15:43:10 +0000 (GMT) +X-Greylist: delayed 01:00:03.527391 by SQLgrey- +Received: from vms046pub.verizon.net (vms046pub.verizon.net [206.46.252.46]) + by svr1.postgresql.org (Postfix) with ESMTP id A02F6D89CA + for ; + Thu, 10 Nov 2005 11:43:11 -0400 (AST) +Received: from osgiliath.mathom.us ([70.108.64.202]) + by vms046.mailsrvcs.net (Sun Java System Messaging Server 6.2-4.02 + (built Sep + 9 2005)) with ESMTPA id <0IPQ00K7XU7XQQ70@vms046.mailsrvcs.net> for + pgsql-performance@postgresql.org; Thu, 10 Nov 2005 08:43:10 -0600 (CST) +Received: from localhost (localhost [127.0.0.1]) + by osgiliath.mathom.us (Postfix) with ESMTP id 867416001EE for + ; + Thu, 10 Nov 2005 09:43:09 -0500 (EST) +Received: from osgiliath.mathom.us ([127.0.0.1]) + by localhost (osgiliath [127.0.0.1]) (amavisd-new, port 10024) + with LMTP id 29980-06-3 for ; Thu, + 10 Nov 2005 09:43:09 -0500 (EST) +Received: by osgiliath.mathom.us (Postfix, from userid 1000) + id 6B30E6001E3; Thu, 10 Nov 2005 09:43:09 -0500 (EST) +Date: Thu, 10 Nov 2005 09:43:09 -0500 +From: Michael Stone +Subject: Re: WAL sync behaviour +In-reply-to: <20051110142535.GA4530@uio.no> +To: pgsql-performance@postgresql.org +Mail-Followup-To: pgsql-performance@postgresql.org +Message-id: <20051110144309.GO9905@mathom.us> +MIME-version: 1.0 +Content-type: text/plain; charset=us-ascii; format=flowed +Content-disposition: inline +X-Pgp-Fingerprint: 53 FF 38 00 E7 DD 0A 9C 84 52 84 C5 EE DF 7C 88 +X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at mathom.us +References: <20051110133241.GA4031@uio.no> <437355C6.4030604@archonet.com> + <20051110142535.GA4530@uio.no> +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.003 required=5 tests=[AWL=0.003] +X-Spam-Score: 0.003 +X-Spam-Level: +X-Archive-Number: 200511/178 +X-Sequence-Number: 15435 + +On Thu, Nov 10, 2005 at 03:25:35PM +0100, Steinar H. Gunderson wrote: +>Ah, yes, I forgot -- it's ext3. We're considering simply moving the WAL onto +>a separate partition (with data=writeback and noatime) if that can help us +>any. + +There's no reason to use a journaled filesystem for the wal. Use ext2 in +preference to ext3. + +Mike Stone + +From pgsql-performance-owner@postgresql.org Thu Nov 10 11:16:12 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id DD6EFD8FC5 + for ; + Thu, 10 Nov 2005 11:16:09 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 36868-08 + for ; + Thu, 10 Nov 2005 15:16:04 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from koolancexeon.g2switchworks.com (mail.g2switchworks.com + [63.87.162.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 2A99ED7BB0 + for ; + Thu, 10 Nov 2005 11:16:06 -0400 (AST) +Received: mail.g2switchworks.com 10.10.1.8 from 10.10.1.37 10.10.1.37 via HTTP + with MS-WebStorage 6.5.6944 +Received: from state.g2switchworks.com by mail.g2switchworks.com; + 10 Nov 2005 09:16:10 -0600 +Subject: Re: Some help on buffers and other performance tricks +From: Scott Marlowe +To: Ron Peacetree +Cc: Frank Wiles , pgsql-performance@postgresql.org +In-Reply-To: + <1793468.1131596410309.JavaMail.root@elwamui-hound.atl.sa.earthlink.net> +References: + <1793468.1131596410309.JavaMail.root@elwamui-hound.atl.sa.earthlink.net> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Message-Id: <1131635770.3554.58.camel@state.g2switchworks.com> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) +Date: Thu, 10 Nov 2005 09:16:10 -0600 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.007 required=5 tests=[AWL=0.006, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.007 +X-Spam-Level: +X-Archive-Number: 200511/176 +X-Sequence-Number: 15433 + +On Wed, 2005-11-09 at 22:20, Ron Peacetree wrote: +> The point Gentlemen, was that Good Architecture is King. That's what I was trying to emphasize by calling proper DB architecture step 0. All other things being equal (and they usually aren't, this sort of stuff is _very_ context dependent), the more of your critical schema that you can fit into RAM during normal operation the better. +> +> ...and it all starts with proper DB design. Otherwise, you are quite right in stating that you risk wasting time, effort, and HW. + + +Very valid point. It's the reason, in my last job, we had a mainline +server with dual 2800MHz CPUs and a big RAID array. + +And our development, build and test system was a Dual Pentium Pro 200 +with 256 Meg of ram. You notice slow queries real fast on such a box. + +From pgsql-performance-owner@postgresql.org Thu Nov 10 11:24:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 75A68DB12C + for ; + Thu, 10 Nov 2005 11:24:44 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 41811-08 + for ; + Thu, 10 Nov 2005 15:24:40 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from frank.wiles.org (frank.wiles.org [24.124.39.75]) + by svr1.postgresql.org (Postfix) with ESMTP id 72D33DB0E7 + for ; + Thu, 10 Nov 2005 11:24:42 -0400 (AST) +Received: from kungfu (frank.wiles.org [127.0.0.1]) + by frank.wiles.org (8.13.1/8.13.1) with SMTP id jAAFOhXR009054; + Thu, 10 Nov 2005 09:24:44 -0600 +Date: Thu, 10 Nov 2005 09:25:01 -0600 +From: Frank Wiles +To: Scott Marlowe +Cc: pgsql-performance@postgresql.org +Subject: Re: Some help on buffers and other performance tricks +Message-Id: <20051110092501.36663aa4.frank@wiles.org> +In-Reply-To: <1131635770.3554.58.camel@state.g2switchworks.com> +References: + <1793468.1131596410309.JavaMail.root@elwamui-hound.atl.sa.earthlink.net> + <1131635770.3554.58.camel@state.g2switchworks.com> +X-Mailer: Sylpheed version 2.0.1 (GTK+ 2.6.10; i686-pc-linux-gnu) +Mime-Version: 1.0 +Content-Type: text/plain; charset=US-ASCII +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.015 required=5 tests=[AWL=0.015] +X-Spam-Score: 0.015 +X-Spam-Level: +X-Archive-Number: 200511/177 +X-Sequence-Number: 15434 + +On Thu, 10 Nov 2005 09:16:10 -0600 +Scott Marlowe wrote: + +> Very valid point. It's the reason, in my last job, we had a mainline +> server with dual 2800MHz CPUs and a big RAID array. +> +> And our development, build and test system was a Dual Pentium Pro 200 +> with 256 Meg of ram. You notice slow queries real fast on such a box. + + I know several people who use this development method. It can + sometimes lead to premature optimizations, but overall I think it is + a great way to work. + + --------------------------------- + Frank Wiles + http://www.wiles.org + --------------------------------- + + +From pgsql-performance-owner@postgresql.org Thu Nov 10 11:43:52 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 74859D8FC5 + for ; + Thu, 10 Nov 2005 11:43:48 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 45211-10 + for ; + Thu, 10 Nov 2005 15:43:44 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (c-24-11-237-16.hsd1.mi.comcast.net + [24.11.237.16]) + by svr1.postgresql.org (Postfix) with ESMTP id B97FDD89CA + for ; + Thu, 10 Nov 2005 11:43:46 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Some help on buffers and other performance tricks +Date: Thu, 10 Nov 2005 10:43:50 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD84A@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Some help on buffers and other performance tricks +Thread-Index: AcXlrtjZZr9lrQTFTfKQB2f7ayk1AAAXYC4Q +From: "Merlin Moncure" +To: "Ron Peacetree" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.242 required=5 tests=[AWL=-0.746, + RCVD_IN_SORBS_DUL=1.988] +X-Spam-Score: 1.242 +X-Spam-Level: * +X-Archive-Number: 200511/179 +X-Sequence-Number: 15436 + +> The point Gentlemen, was that Good Architecture is King. That's what +I +> was trying to emphasize by calling proper DB architecture step 0. All +> other things being equal (and they usually aren't, this sort of stuff +is +> _very_ context dependent), the more of your critical schema that you +can +> fit into RAM during normal operation the better. +>=20 +> ...and it all starts with proper DB design. Otherwise, you are quite +> right in stating that you risk wasting time, effort, and HW. +>=20 +> Ron + ++1! + +I answer lots of question on this list that are in the form of 'query x +is running to slow'. Often, the first thing that pops in my mind is +'why are you running query x in the first place?' =20 + +The #1 indicator that something is not right is 'distinct' clause. +Distinct (and its evil cousin, union) are often brought in to address +problems. + +The human brain is the best optimizer. Even on old hardware the server +can handle a *lot* of data. It's just about where we add +inefficiency...lousy database designs lead to lousy queries or (even +worse) extra application code. + +Merlin + +From pgsql-performance-owner@postgresql.org Thu Nov 10 11:51:13 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 7F018D90DA + for ; + Thu, 10 Nov 2005 11:51:12 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 56812-01 + for ; + Thu, 10 Nov 2005 15:51:07 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from koolancexeon.g2switchworks.com (mail.g2switchworks.com + [63.87.162.25]) + by svr1.postgresql.org (Postfix) with ESMTP id BB7EDD7C91 + for ; + Thu, 10 Nov 2005 11:51:09 -0400 (AST) +Received: mail.g2switchworks.com 10.10.1.8 from 10.10.1.37 10.10.1.37 via HTTP + with MS-WebStorage 6.5.6944 +Received: from state.g2switchworks.com by mail.g2switchworks.com; + 10 Nov 2005 09:51:14 -0600 +Subject: Re: Some help on buffers and other performance tricks +From: Scott Marlowe +To: Frank Wiles +Cc: pgsql-performance@postgresql.org +In-Reply-To: <20051110092501.36663aa4.frank@wiles.org> +References: + <1793468.1131596410309.JavaMail.root@elwamui-hound.atl.sa.earthlink.net> + <1131635770.3554.58.camel@state.g2switchworks.com> + <20051110092501.36663aa4.frank@wiles.org> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Message-Id: <1131637874.3554.73.camel@state.g2switchworks.com> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) +Date: Thu, 10 Nov 2005 09:51:14 -0600 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.007 required=5 tests=[AWL=0.006, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.007 +X-Spam-Level: +X-Archive-Number: 200511/180 +X-Sequence-Number: 15437 + +On Thu, 2005-11-10 at 09:25, Frank Wiles wrote: +> On Thu, 10 Nov 2005 09:16:10 -0600 +> Scott Marlowe wrote: +> +> > Very valid point. It's the reason, in my last job, we had a mainline +> > server with dual 2800MHz CPUs and a big RAID array. +> > +> > And our development, build and test system was a Dual Pentium Pro 200 +> > with 256 Meg of ram. You notice slow queries real fast on such a box. +> +> I know several people who use this development method. It can +> sometimes lead to premature optimizations, but overall I think it is +> a great way to work. + +Hehe. Yeah, you get used to things running a bit slower pretty +quickly. Keep in mind though, that the test box is likely only +supporting one single application at a time, whereas the production +server may be running dozens or even hundreds of apps, so it's important +to catch performance issues before they get to production. + +Plus, the Dual PPRo 200 WAS running a decent RAID array, even if it was +a linux kernel software RAID and not hardware. But it was on 8 9 +gigabyte SCSI drives, so it was quite fast for reads. + +In actuality, a lot of the folks developed their code on their own +workstations (generally 1+GHz machines with 1G or more of ram) then had +to move them over to the ppro 200 for testing and acceptance. So that +kind of helps stop the premature optimizations. We were mainly looking +to catch stupidity before it got to production. + +From pgsql-performance-owner@postgresql.org Thu Nov 10 11:52:36 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 07D34D89CA + for ; + Thu, 10 Nov 2005 11:52:35 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 57127-02 + for ; + Thu, 10 Nov 2005 15:52:31 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from koolancexeon.g2switchworks.com (mail.g2switchworks.com + [63.87.162.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 85DB2D7C91 + for ; + Thu, 10 Nov 2005 11:52:33 -0400 (AST) +Received: mail.g2switchworks.com 10.10.1.8 from 10.10.1.37 10.10.1.37 via HTTP + with MS-WebStorage 6.5.6944 +Received: from state.g2switchworks.com by mail.g2switchworks.com; + 10 Nov 2005 09:52:38 -0600 +Subject: Re: WAL sync behaviour +From: Scott Marlowe +To: Michael Stone +Cc: pgsql-performance@postgresql.org +In-Reply-To: <20051110144309.GO9905@mathom.us> +References: <20051110133241.GA4031@uio.no> <437355C6.4030604@archonet.com> + <20051110142535.GA4530@uio.no> <20051110144309.GO9905@mathom.us> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Message-Id: <1131637958.3554.75.camel@state.g2switchworks.com> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) +Date: Thu, 10 Nov 2005 09:52:38 -0600 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.007 required=5 tests=[AWL=0.006, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.007 +X-Spam-Level: +X-Archive-Number: 200511/181 +X-Sequence-Number: 15438 + +On Thu, 2005-11-10 at 08:43, Michael Stone wrote: +> On Thu, Nov 10, 2005 at 03:25:35PM +0100, Steinar H. Gunderson wrote: +> >Ah, yes, I forgot -- it's ext3. We're considering simply moving the WAL onto +> >a separate partition (with data=writeback and noatime) if that can help us +> >any. +> +> There's no reason to use a journaled filesystem for the wal. Use ext2 in +> preference to ext3. + +Not from what I understood. Ext2 can't guarantee that your data will +even be there in any form after a crash. I believe only metadata +journaling is needed though. + +From pgsql-performance-owner@postgresql.org Thu Nov 10 12:04:01 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B0E13DB1D4 + for ; + Thu, 10 Nov 2005 12:03:59 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 59891-07 + for ; + Thu, 10 Nov 2005 16:03:55 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from vms048pub.verizon.net (vms048pub.verizon.net [206.46.252.48]) + by svr1.postgresql.org (Postfix) with ESMTP id 90A7ADB178 + for ; + Thu, 10 Nov 2005 12:03:55 -0400 (AST) +Received: from osgiliath.mathom.us ([70.108.64.202]) + by vms048.mailsrvcs.net (Sun Java System Messaging Server 6.2-4.02 + (built Sep + 9 2005)) with ESMTPA id <0IPQ0055QXTJJOB1@vms048.mailsrvcs.net> for + pgsql-performance@postgresql.org; Thu, 10 Nov 2005 10:00:56 -0600 (CST) +Received: from localhost (localhost [127.0.0.1]) + by osgiliath.mathom.us (Postfix) with ESMTP id 33BDB6001EE; Thu, + 10 Nov 2005 11:00:55 -0500 (EST) +Received: from osgiliath.mathom.us ([127.0.0.1]) + by localhost (osgiliath [127.0.0.1]) (amavisd-new, port 10024) + with LMTP id 30964-05-4; Thu, 10 Nov 2005 11:00:55 -0500 (EST) +Received: by osgiliath.mathom.us (Postfix, from userid 1000) + id 15B296001D7; Thu, 10 Nov 2005 11:00:55 -0500 (EST) +Date: Thu, 10 Nov 2005 11:00:55 -0500 +From: Michael Stone +Subject: Re: WAL sync behaviour +In-reply-to: <1131637958.3554.75.camel@state.g2switchworks.com> +To: Scott Marlowe +Cc: pgsql-performance@postgresql.org +Mail-Followup-To: Scott Marlowe , + pgsql-performance@postgresql.org +Message-id: <20051110160054.GP9905@mathom.us> +MIME-version: 1.0 +Content-type: text/plain; charset=us-ascii; format=flowed +Content-disposition: inline +X-Pgp-Fingerprint: 53 FF 38 00 E7 DD 0A 9C 84 52 84 C5 EE DF 7C 88 +X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at mathom.us +References: <20051110133241.GA4031@uio.no> <437355C6.4030604@archonet.com> + <20051110142535.GA4530@uio.no> <20051110144309.GO9905@mathom.us> + <1131637958.3554.75.camel@state.g2switchworks.com> +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.003 required=5 tests=[AWL=0.003] +X-Spam-Score: 0.003 +X-Spam-Level: +X-Archive-Number: 200511/182 +X-Sequence-Number: 15439 + +On Thu, Nov 10, 2005 at 09:52:38AM -0600, Scott Marlowe wrote: +>Not from what I understood. Ext2 can't guarantee that your data will +>even be there in any form after a crash. + +It can if you sync the data. (Which is the whole point of the WAL.) + +>I believe only metadata journaling is needed though. + +If you don't sync, metadata journaling doesn't do anything to guarantee +that your data will be there, so you're adding no data security in the +non-synchronous-write case. (Which is irrelevant for the WAL.) + +What metadata journalling gets you is fast recovery from crashes by +avoiding a fsck. The fsck time is related to the number of files on a +filesystem--so it's generally pretty quick on a WAL partition anyway. + +Mike Stone + +From pgsql-performance-owner@postgresql.org Thu Nov 10 12:23:35 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 191C0DA081 + for ; + Thu, 10 Nov 2005 12:23:33 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 61309-09 + for ; + Thu, 10 Nov 2005 16:23:30 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from pop-altamira.atl.sa.earthlink.net + (pop-altamira.atl.sa.earthlink.net [207.69.195.62]) + by svr1.postgresql.org (Postfix) with ESMTP id 24BA4D7BAF + for ; + Thu, 10 Nov 2005 12:23:30 -0400 (AST) +Received: from elwamui-hound.atl.sa.earthlink.net ([209.86.224.34]) + by pop-altamira.atl.sa.earthlink.net with esmtp (Exim 3.36 #10) + id 1EaFCt-000011-00; Thu, 10 Nov 2005 11:23:23 -0500 +Message-ID: + <16531385.1131639803429.JavaMail.root@elwamui-hound.atl.sa.earthlink.net> +Date: Thu, 10 Nov 2005 11:23:23 -0500 (EST) +From: Ron Peacetree +Reply-To: Ron Peacetree +To: Kurt De Grave , + pgsql-performance@postgresql.org +Subject: Re: Sort performance on large tables +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Mailer: EarthLink Zoo Mail 1.0 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.312 required=5 tests=[AWL=-0.167, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.312 +X-Spam-Level: +X-Archive-Number: 200511/183 +X-Sequence-Number: 15440 + +My original post did not take into account VAT, I apologize for that oversight. + +However, unless you are naive, or made of gold, or have some sort of "special" relationship that requires you to, _NE VER_ buy RAM from your computer HW OEM. For at least two decades it's been a provable fact that OEMs like DEC, Sun, HP, Compaq, Dell, etc, etc charge far more per GB for the RAM they sell. Same goes for HDs. Buy your memory and HDs direct from reputable manufacturers, you'll get at least the same quality and pay considerably less. + +Your Dell example is evidence that supports my point. As of this writing, decent RAM should cost $75-$150 pr GB (not including VAT ;-) ). Don't let yourself be conned into paying more. + +I'm talking about decent RAM from reputable direct suppliers like Corsair and Kingston (_not_ their Value RAM, the actual Kingston branded stuff), OCZ, etc. Such companies sell via multiple channels, including repuatble websites like dealtime.com, pricewatch.com, newegg.com, etc, etc. + +You are quite correct that there's poor quality junk out there. I was not talking about it, only reasonable quality components. + +Ron + + +-----Original Message----- +From: Kurt De Grave +Sent: Nov 10, 2005 5:40 AM +To: Ron Peacetree +Cc: Charlie Savage , pgsql-performance@postgresql.org +Subject: Re: [PERFORM] Sort performance on large tables + + + +On Wed, 9 Nov 2005, Ron Peacetree wrote: + +> At this writing, 4 1GB DIMMs (4GB) should set you back ~$300 or less. +> 4 2GB DIMMs (8GB) should cost ~$600. As of now, very few mainboards +> support 4GB DIMMs and I doubt the D3000 has such a mainboard. If you +> can use them, 4 4GB DIMMs (16GB) will currently set you back +> ~$1600-$2400. + +Sorry, but every time again I see unrealistic memory prices quoted when +the buy-more-memory argument passes by. +What kind of memory are you buying for your servers? Non-ECC no-name +memory that doesn't even pass a one-hour memtest86 for 20% of the items +you buy? + +Just checked at Dell's web page: adding 4 1GB DIMMs to a PowerEdge 2850 +sets you back _1280 EURO_ excluding VAT. And that's after they already +charged you 140 euro for replacing the obsolete standard 4 512MB DIMMs +with the same capacity in 1GB DIMMs. So the 4GB upgrade actually costs +1420 euro plus VAT, which is quite a bit more than $300. + +Okay, few people will happily buy at those prices. You can get the +exact same goods much cheaper elsewhere, but it'll still cost you way +more than the number you gave, plus you'll have to drive to the server's +location, open up the box yourself, and risk incompatibilities and +support problems if there's ever something wrong with that memory. + +Disclaimers: +I know that you're talking about a desktop in this particular case. +I wouldn't see a need for ECC in a development box either. +I know a Dell hasn't been the smartest choice for a database box lately +(but politics...). + +kurt. + + + +From pgsql-performance-owner@postgresql.org Thu Nov 10 12:34:07 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 439BCD7BAF + for ; + Thu, 10 Nov 2005 12:34:06 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 67703-07 + for ; + Thu, 10 Nov 2005 16:34:04 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.202]) + by svr1.postgresql.org (Postfix) with ESMTP id 822DDD7B75 + for ; + Thu, 10 Nov 2005 12:34:04 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id 57so383386wri + for ; + Thu, 10 Nov 2005 08:34:04 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=sVJL0tFT0QGeEnp3PIycXcDOWh7oy/KLYS/ffmFWRMqpDZ+64tNpGk1aroSNyqzFm9W/ZhYH+Y3ngx4aQm9VRYyK0tUsGAslS1By0fDnTUNRP5MbhIWFX4kTZVuxaIy4/bK/aCqYBVWoHdHtYlOPy2J/V0TZOGehmj9amE+gAbE= +Received: by 10.54.142.2 with SMTP id p2mr813453wrd; + Thu, 10 Nov 2005 08:34:03 -0800 (PST) +Received: by 10.54.83.19 with HTTP; Thu, 10 Nov 2005 08:34:03 -0800 (PST) +Message-ID: <33c6269f0511100834q718e5274mf7230fe95ab8323e@mail.gmail.com> +Date: Thu, 10 Nov 2005 11:34:03 -0500 +From: Alex Turner +To: Ron Peacetree +Subject: Re: Sort performance on large tables +Cc: Kurt De Grave , + pgsql-performance@postgresql.org +In-Reply-To: + <16531385.1131639803429.JavaMail.root@elwamui-hound.atl.sa.earthlink.net> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: + <16531385.1131639803429.JavaMail.root@elwamui-hound.atl.sa.earthlink.net> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.092 required=5 tests=[AWL=0.092] +X-Spam-Score: 0.092 +X-Spam-Level: +X-Archive-Number: 200511/184 +X-Sequence-Number: 15441 + +We use this memory in all our servers (well - the 512 sticks). 0 +problems to date: + +http://www.newegg.com/Product/Product.asp?Item=3DN82E16820145513 + +$163 for 1GB. + +This stuff is probably better than the Samsung RAM dell is selling you +for 3 times the price. + +Alex + +On 11/10/05, Ron Peacetree wrote: +> My original post did not take into account VAT, I apologize for that over= +sight. +> +> However, unless you are naive, or made of gold, or have some sort of "spe= +cial" relationship that requires you to, _NE VER_ buy RAM from your compute= +r HW OEM. For at least two decades it's been a provable fact that OEMs lik= +e DEC, Sun, HP, Compaq, Dell, etc, etc charge far more per GB for the RAM t= +hey sell. Same goes for HDs. Buy your memory and HDs direct from reputabl= +e manufacturers, you'll get at least the same quality and pay considerably = +less. +> +> Your Dell example is evidence that supports my point. As of this writing= +, decent RAM should cost $75-$150 pr GB (not including VAT ;-) ). Don't l= +et yourself be conned into paying more. +> +> I'm talking about decent RAM from reputable direct suppliers like Corsair= + and Kingston (_not_ their Value RAM, the actual Kingston branded stuff), O= +CZ, etc. Such companies sell via multiple channels, including repuatble we= +bsites like dealtime.com, pricewatch.com, newegg.com, etc, etc. +> +> You are quite correct that there's poor quality junk out there. I was no= +t talking about it, only reasonable quality components. +> +> Ron +> +> +> -----Original Message----- +> From: Kurt De Grave +> Sent: Nov 10, 2005 5:40 AM +> To: Ron Peacetree +> Cc: Charlie Savage , pgsql-performance@postgresql.org +> Subject: Re: [PERFORM] Sort performance on large tables +> +> +> +> On Wed, 9 Nov 2005, Ron Peacetree wrote: +> +> > At this writing, 4 1GB DIMMs (4GB) should set you back ~$300 or less. +> > 4 2GB DIMMs (8GB) should cost ~$600. As of now, very few mainboards +> > support 4GB DIMMs and I doubt the D3000 has such a mainboard. If you +> > can use them, 4 4GB DIMMs (16GB) will currently set you back +> > ~$1600-$2400. +> +> Sorry, but every time again I see unrealistic memory prices quoted when +> the buy-more-memory argument passes by. +> What kind of memory are you buying for your servers? Non-ECC no-name +> memory that doesn't even pass a one-hour memtest86 for 20% of the items +> you buy? +> +> Just checked at Dell's web page: adding 4 1GB DIMMs to a PowerEdge 2850 +> sets you back _1280 EURO_ excluding VAT. And that's after they already +> charged you 140 euro for replacing the obsolete standard 4 512MB DIMMs +> with the same capacity in 1GB DIMMs. So the 4GB upgrade actually costs +> 1420 euro plus VAT, which is quite a bit more than $300. +> +> Okay, few people will happily buy at those prices. You can get the +> exact same goods much cheaper elsewhere, but it'll still cost you way +> more than the number you gave, plus you'll have to drive to the server's +> location, open up the box yourself, and risk incompatibilities and +> support problems if there's ever something wrong with that memory. +> +> Disclaimers: +> I know that you're talking about a desktop in this particular case. +> I wouldn't see a need for ECC in a development box either. +> I know a Dell hasn't been the smartest choice for a database box lately +> (but politics...). +> +> kurt. +> +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 3: Have you checked our extensive FAQ? +> +> http://www.postgresql.org/docs/faq +> + +From pgsql-performance-owner@postgresql.org Thu Nov 10 12:39:39 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B1F33D9DFD + for ; + Thu, 10 Nov 2005 12:39:37 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 68950-09 + for ; + Thu, 10 Nov 2005 16:39:36 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 35C00D8FC5 + for ; + Thu, 10 Nov 2005 12:39:36 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAAGdYFW009792; + Thu, 10 Nov 2005 11:39:34 -0500 (EST) +To: Scott Marlowe +Cc: Michael Stone , + pgsql-performance@postgresql.org +Subject: Re: WAL sync behaviour +In-reply-to: <1131637958.3554.75.camel@state.g2switchworks.com> +References: <20051110133241.GA4031@uio.no> <437355C6.4030604@archonet.com> + <20051110142535.GA4530@uio.no> <20051110144309.GO9905@mathom.us> + <1131637958.3554.75.camel@state.g2switchworks.com> +Comments: In-reply-to Scott Marlowe + message dated "Thu, 10 Nov 2005 09:52:38 -0600" +Date: Thu, 10 Nov 2005 11:39:34 -0500 +Message-ID: <9791.1131640774@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/185 +X-Sequence-Number: 15442 + +Scott Marlowe writes: +> On Thu, 2005-11-10 at 08:43, Michael Stone wrote: +>> There's no reason to use a journaled filesystem for the wal. Use ext2 in +>> preference to ext3. + +> Not from what I understood. Ext2 can't guarantee that your data will +> even be there in any form after a crash. I believe only metadata +> journaling is needed though. + +No, Mike is right: for WAL you shouldn't need any journaling. This is +because we zero out *and fsync* an entire WAL file before we ever +consider putting live WAL data in it. During live use of a WAL file, +its metadata is not changing. As long as the filesystem follows +the minimal rule of syncing metadata about a file when it fsyncs the +file, all the live WAL files should survive crashes OK. + +We can afford to do this mainly because WAL files can normally be +recycled instead of created afresh, so the zero-out overhead doesn't +get paid during normal operation. + +You do need metadata journaling for all non-WAL PG files, since we don't +fsync them every time we extend them; which means the filesystem could +lose track of which disk blocks belong to such a file, if it's not +journaled. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Thu Nov 10 13:11:57 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 98EE9DAA17 + for ; + Thu, 10 Nov 2005 13:11:56 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 03886-09 + for ; + Thu, 10 Nov 2005 17:11:54 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.envyfinancial.com (unknown [206.248.142.186]) + by svr1.postgresql.org (Postfix) with ESMTP id 313A5DA7BA + for ; + Thu, 10 Nov 2005 13:11:53 -0400 (AST) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by mail.envyfinancial.com (Postfix) with ESMTP id BDBE21D9B9; + Thu, 10 Nov 2005 11:53:13 -0500 (EST) +Received: from mail.envyfinancial.com ([127.0.0.1]) + by localhost (mark.mielke.cc [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id 14478-02; Thu, 10 Nov 2005 11:53:13 -0500 (EST) +Received: by mail.envyfinancial.com (Postfix, from userid 500) + id 7BC701D9D1; Thu, 10 Nov 2005 11:53:13 -0500 (EST) +Date: Thu, 10 Nov 2005 11:53:13 -0500 +From: mark@mark.mielke.cc +To: Tom Lane +Cc: Scott Marlowe , + Michael Stone , pgsql-performance@postgresql.org +Subject: Re: WAL sync behaviour +Message-ID: <20051110165313.GA14444@mark.mielke.cc> +References: <20051110133241.GA4031@uio.no> <437355C6.4030604@archonet.com> + <20051110142535.GA4530@uio.no> <20051110144309.GO9905@mathom.us> + <1131637958.3554.75.camel@state.g2switchworks.com> + <9791.1131640774@sss.pgh.pa.us> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <9791.1131640774@sss.pgh.pa.us> +User-Agent: Mutt/1.4.2.1i +X-Virus-Scanned: amavisd-new at mail.envyfinancial.com +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.399 required=5 tests=[AWL=-0.151, + NO_REAL_NAME=0.55] +X-Spam-Score: 0.399 +X-Spam-Level: +X-Archive-Number: 200511/189 +X-Sequence-Number: 15446 + +On Thu, Nov 10, 2005 at 11:39:34AM -0500, Tom Lane wrote: +> No, Mike is right: for WAL you shouldn't need any journaling. This is +> because we zero out *and fsync* an entire WAL file before we ever +> consider putting live WAL data in it. During live use of a WAL file, +> its metadata is not changing. As long as the filesystem follows +> the minimal rule of syncing metadata about a file when it fsyncs the +> file, all the live WAL files should survive crashes OK. + +Yes, with emphasis on the zero out... :-) + +> You do need metadata journaling for all non-WAL PG files, since we don't +> fsync them every time we extend them; which means the filesystem could +> lose track of which disk blocks belong to such a file, if it's not +> journaled. + +I think there may be theoretical problems with regard to the ordering +of the fsync operation, for files that are not pre-allocated. For +example, if a new block is allocated - there are two blocks that need +to be updated. The indirect reference block (or inode block, if block +references fit into the inode entry), and the block itself. If the +indirect reference block is written first, before the data block, the +state of the disk is inconsistent. This would be a crash during the +fsync() operation. The metadata journalling can ensure that the data +block is allocated first, and then all the necessary references +updated, allowing for the operation to be incomplete and rolled back, +or committed in full. + +Or, that is my understanding, anyways, and this is why I would not use +ext2 for the database, even if it was claimed that fsync() was used. + +For WAL, with pre-allocated zero blocks? Sure. Ext2... :-) + +mark + +-- +mark@mielke.cc / markm@ncf.ca / markm@nortel.com __________________________ +. . _ ._ . . .__ . . ._. .__ . . . .__ | Neighbourhood Coder +|\/| |_| |_| |/ |_ |\/| | |_ | |/ |_ | +| | | | | \ | \ |__ . | | .|. |__ |__ | \ |__ | Ottawa, Ontario, Canada + + One ring to rule them all, one ring to find them, one ring to bring them all + and in the darkness bind them... + + http://mark.mielke.cc/ + + +From pgsql-performance-owner@postgresql.org Thu Nov 10 12:59:37 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 027EADA461 + for ; + Thu, 10 Nov 2005 12:59:35 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 75412-09 + for ; + Thu, 10 Nov 2005 16:59:28 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id AD7B9D70C0 + for ; + Thu, 10 Nov 2005 12:59:27 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id D832E31059; Thu, 10 Nov 2005 17:59:26 +0100 (MET) +From: Charlie Savage +X-Newsgroups: pgsql.performance +Subject: Index Scan Costs versus Sort +Date: Thu, 10 Nov 2005 09:59:21 -0700 +Organization: Hub.Org Networking Services +Lines: 324 +Message-ID: +Mime-Version: 1.0 +Content-Type: text/plain; charset=UTF-8; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +User-Agent: Thunderbird 1.5 (Windows/20051025) +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/187 +X-Sequence-Number: 15444 + +This is related to my post the other day about sort performance. + +Part of my problem seems to be that postgresql is greatly overestimating +the cost of index scans. As a result, it prefers query plans that +involve seq scans and sorts versus query plans that use index scans. +Here is an example query: + +SELECT tlid, count(tlid) +FROM completechain +GROUP BY tlid; + +Approach #1 - seq scan with sort: + +"GroupAggregate (cost=10177594.61..11141577.89 rows=48199164 width=4) +(actual time=7439085.877..8429628.234 rows=47599910 loops=1)" +" -> Sort (cost=10177594.61..10298092.52 rows=48199164 width=4) +(actual time=7439085.835..8082452.721 rows=48199165 loops=1)" +" Sort Key: tlid" +" -> Seq Scan on completechain (cost=0.00..2229858.64 +rows=48199164 width=4) (actual time=10.788..768403.874 rows=48199165 +loops=1)" +"Total runtime: 8596987.505 ms" + + +Approach #2 - index scan (done by setting enable_seqscan to false and +enable_sort to false): + +"GroupAggregate (cost=0.00..113713861.43 rows=48199164 width=4) (actual +time=53.211..2652227.201 rows=47599910 loops=1)" +" -> Index Scan using idx_completechain_tlid on completechain +(cost=0.00..112870376.06 rows=48199164 width=4) (actual +time=53.168..2312426.321 rows=48199165 loops=1)" +"Total runtime: 2795420.933 ms" + +Approach #1 is estimated to be 10 times less costly, yet takes 3 times +longer to execute. + + +My questions: + +1. Postgresql estimates the index scan will be 50 times more costly +than the seq scan (112870376 vs 2229858) yet in fact it only takes 3 +times longer to execute (2312426 s vs. 768403 s). My understanding is +that postgresql assumes, via the random_page_cost parameter, that an +index scan will take 4 times longer than a sequential scan. So why is +the analyzer estimating it is 50 times slower? + +2. In approach #1, the planner thinks the sort will take roughly 4 +times longer [(10,298,092 - 2,229,858) / 2,229,858] than the sequential +scan. Yet it really takes almost ten times longer. It seems as is the +planner is greatly underestimating the sort cost? + +Due to these two apparent miscalculations, postgresql is choosing the +wrong query plan to execute this query. I've attached my +postgresql.conf file below just in case this is due to some +misconfiguration on my part. + +Some setup notes: +* All tables are vacuumed and analyzed +* Running Postgresql 8.1 on Suse 10 +* Low end hardware - Dell Dimension 3000, 1GB ram, 1 built-in 80 GB IDE +drive, 1 SATA Seagate 400GB drive. The IDE drive has the OS and the WAL +files, the SATA drive the database. From hdparm the max IO for the IDE +drive is about 50Mb/s and the SATA drive is about 65Mb/s. + + +------------------------------- + +#--------------------------------------------------------------------------- +# RESOURCE USAGE (except WAL) +#--------------------------------------------------------------------------- + +shared_buffers = 40000 # 40000 buffers * 8192 +bytes/buffer = 327,680,000 bytes +#shared_buffers = 1000 # min 16 or max_connections*2, 8KB each + +temp_buffers = 5000 +#temp_buffers = 1000 # min 100, 8KB each +#max_prepared_transactions = 5 # can be 0 or more +# note: increasing max_prepared_transactions costs ~600 bytes of shared +memory +# per transaction slot, plus lock space (see max_locks_per_transaction). + +work_mem = 16384 # in Kb +#work_mem = 1024 # min 64, size in KB + +maintenance_work_mem = 262144 # in kb +#maintenance_work_mem = 16384 # min 1024, size in KB +#max_stack_depth = 2048 # min 100, size in KB + +# - Free Space Map - + +max_fsm_pages = 60000 +#max_fsm_pages = 20000 # min max_fsm_relations*16, 6 bytes each + +#max_fsm_relations = 1000 # min 100, ~70 bytes each + +# - Kernel Resource Usage - + +#max_files_per_process = 1000 # min 25 +#preload_libraries = '' + +# - Cost-Based Vacuum Delay - + +#vacuum_cost_delay = 0 # 0-1000 milliseconds +#vacuum_cost_page_hit = 1 # 0-10000 credits +#vacuum_cost_page_miss = 10 # 0-10000 credits +#vacuum_cost_page_dirty = 20 # 0-10000 credits +#vacuum_cost_limit = 200 # 0-10000 credits + +# - Background writer - + +#bgwriter_delay = 200 # 10-10000 milliseconds between rounds +#bgwriter_lru_percent = 1.0 # 0-100% of LRU buffers scanned/round +#bgwriter_lru_maxpages = 5 # 0-1000 buffers max written/round +#bgwriter_all_percent = 0.333 # 0-100% of all buffers scanned/round +#bgwriter_all_maxpages = 5 # 0-1000 buffers max written/round + + +#--------------------------------------------------------------------------- +# WRITE AHEAD LOG +#--------------------------------------------------------------------------- + +# - Settings - + +fsync = on # turns forced synchronization on or off +#wal_sync_method = fsync # the default is the first option + # supported by the operating system: + # open_datasync + # fdatasync + # fsync + # fsync_writethrough + # open_sync +#full_page_writes = on # recover from partial page writes + +wal_buffers = 128 +#wal_buffers = 8 # min 4, 8KB each + +#commit_delay = 0 # range 0-100000, in microseconds +#commit_siblings = 5 # range 1-1000 + +# - Checkpoints - + +checkpoint_segments = 256 # 256 * 16Mb = 4,294,967,296 bytes +checkpoint_timeout = 1200 # 1200 seconds (20 minutes) +checkpoint_warning = 30 # in seconds, 0 is off + +#checkpoint_segments = 3 # in logfile segments, min 1, 16MB each +#checkpoint_timeout = 300 # range 30-3600, in seconds +#checkpoint_warning = 30 # in seconds, 0 is off + +# - Archiving - + +#archive_command = '' # command to use to archive a logfile + # segment + + +#--------------------------------------------------------------------------- +# QUERY TUNING +#--------------------------------------------------------------------------- + +# - Planner Method Configuration - + +#enable_bitmapscan = on +#enable_hashagg = on +#enable_hashjoin = on +#enable_indexscan = on +#enable_mergejoin = on +#enable_nestloop = on +#enable_seqscan = on +#enable_sort = on +#enable_tidscan = on + +# - Planner Cost Constants - + +effective_cache_size = 80000 # 80000 * 8192 = 655,360,000 bytes +#effective_cache_size = 1000 # typically 8KB each + +random_page_cost = 2.5 # units are one sequential page fetch +#random_page_cost = 4 # units are one sequential page fetch + # cost +#cpu_tuple_cost = 0.01 # (same) +#cpu_index_tuple_cost = 0.001 # (same) +#cpu_operator_cost = 0.0025 # (same) + +# - Genetic Query Optimizer - + +#geqo = on +#geqo_threshold = 12 +#geqo_effort = 5 # range 1-10 +#geqo_pool_size = 0 # selects default based on effort +#geqo_generations = 0 # selects default based on effort +#geqo_selection_bias = 2.0 # range 1.5-2.0 + +# - Other Planner Options - + +default_statistics_target = 100 # range 1-1000 +#default_statistics_target = 10 # range 1-1000 +#constraint_exclusion = off +#from_collapse_limit = 8 +#join_collapse_limit = 8 # 1 disables collapsing of explicit + # JOINs + + +#--------------------------------------------------------------------------- +#--------------------------------------------------------------------------- +# RUNTIME STATISTICS +#--------------------------------------------------------------------------- + +# - Statistics Monitoring - + +#log_parser_stats = off +#log_planner_stats = off +#log_executor_stats = off +#log_statement_stats = off + +# - Query/Index Statistics Collector - + +stats_start_collector = on +stats_command_string = on +stats_block_level = on +stats_row_level = on + +#stats_start_collector = on +#stats_command_string = off +#stats_block_level = off +#stats_row_level = off +#stats_reset_on_server_start = off + + +#--------------------------------------------------------------------------- +# AUTOVACUUM PARAMETERS +#--------------------------------------------------------------------------- + +autovacuum = true +autovacuum_naptime = 600 + +#autovacuum = false # enable autovacuum subprocess? +#autovacuum_naptime = 60 # time between autovacuum runs, in secs +#autovacuum_vacuum_threshold = 1000 # min # of tuple updates before + # vacuum +#autovacuum_analyze_threshold = 500 # min # of tuple updates before + # analyze +#autovacuum_vacuum_scale_factor = 0.4 # fraction of rel size before + # vacuum +#autovacuum_analyze_scale_factor = 0.2 # fraction of rel size before + # analyze +#autovacuum_vacuum_cost_delay = -1 # default vacuum cost delay for + # autovac, -1 means use + # vacuum_cost_delay +#autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for + # autovac, -1 means use + # vacuum_cost_ + + +---------------------- +-- Table: tiger.completechain + +-- DROP TABLE tiger.completechain; + +CREATE TABLE tiger.completechain +( + ogc_fid int4 NOT NULL DEFAULT +nextval('completechain_ogc_fid_seq'::regclass), + module varchar(8) NOT NULL, + tlid int4 NOT NULL, + side1 int4, + source varchar(1) NOT NULL, + fedirp varchar(2), + fename varchar(30), + fetype varchar(4), + fedirs varchar(2), + cfcc varchar(3) NOT NULL, + fraddl varchar(11), + toaddl varchar(11), + fraddr varchar(11), + toaddr varchar(11), + friaddl varchar(1), + toiaddl varchar(1), + friaddr varchar(1), + toiaddr varchar(1), + zipl int4, + zipr int4, + aianhhfpl int4, + aianhhfpr int4, + aihhtlil varchar(1), + aihhtlir varchar(1), + census1 varchar(1), + census2 varchar(1), + statel int4, + stater int4, + countyl int4, + countyr int4, + cousubl int4, + cousubr int4, + submcdl int4, + submcdr int4, + placel int4, + placer int4, + tractl int4, + tractr int4, + blockl int4, + blockr int4, + wkb_geometry public.geometry NOT NULL, + CONSTRAINT enforce_dims_wkb_geometry CHECK (ndims(wkb_geometry) = 2), + CONSTRAINT enforce_geotype_wkb_geometry CHECK +(geometrytype(wkb_geometry) = 'LINESTRING'::text OR wkb_geometry IS NULL), + CONSTRAINT enforce_srid_wkb_geometry CHECK (srid(wkb_geometry) = 4269) +) +WITHOUT OIDS; +ALTER TABLE tiger.completechain OWNER TO postgres; + + +-- Index: tiger.idx_completechain_tlid + +-- DROP INDEX tiger.idx_completechain_tlid; + +CREATE INDEX idx_completechain_tlid + ON tiger.completechain + USING btree + (tlid); + + + + +From pgsql-performance-owner@postgresql.org Thu Nov 10 13:00:14 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6EC84DB159 + for ; + Thu, 10 Nov 2005 13:00:13 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 95615-06 + for ; + Thu, 10 Nov 2005 17:00:12 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from koolancexeon.g2switchworks.com (mail.g2switchworks.com + [63.87.162.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 4F320DB129 + for ; + Thu, 10 Nov 2005 13:00:10 -0400 (AST) +Received: mail.g2switchworks.com 10.10.1.8 from 10.10.1.37 10.10.1.37 via HTTP + with MS-WebStorage 6.5.6944 +Received: from state.g2switchworks.com by mail.g2switchworks.com; + 10 Nov 2005 11:00:10 -0600 +Subject: Re: WAL sync behaviour +From: Scott Marlowe +To: Tom Lane +Cc: Michael Stone , + pgsql-performance@postgresql.org +In-Reply-To: <9791.1131640774@sss.pgh.pa.us> +References: <20051110133241.GA4031@uio.no> <437355C6.4030604@archonet.com> + <20051110142535.GA4530@uio.no> <20051110144309.GO9905@mathom.us> + <1131637958.3554.75.camel@state.g2switchworks.com> + <9791.1131640774@sss.pgh.pa.us> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Message-Id: <1131642009.3554.87.camel@state.g2switchworks.com> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) +Date: Thu, 10 Nov 2005 11:00:10 -0600 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.007 required=5 tests=[AWL=0.006, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.007 +X-Spam-Level: +X-Archive-Number: 200511/188 +X-Sequence-Number: 15445 + +On Thu, 2005-11-10 at 10:39, Tom Lane wrote: +> Scott Marlowe writes: +> > On Thu, 2005-11-10 at 08:43, Michael Stone wrote: +> >> There's no reason to use a journaled filesystem for the wal. Use ext2 in +> >> preference to ext3. +> +> > Not from what I understood. Ext2 can't guarantee that your data will +> > even be there in any form after a crash. I believe only metadata +> > journaling is needed though. +> +> No, Mike is right: for WAL you shouldn't need any journaling. This is +> because we zero out *and fsync* an entire WAL file before we ever +> consider putting live WAL data in it. During live use of a WAL file, +> its metadata is not changing. As long as the filesystem follows +> the minimal rule of syncing metadata about a file when it fsyncs the +> file, all the live WAL files should survive crashes OK. +> +> We can afford to do this mainly because WAL files can normally be +> recycled instead of created afresh, so the zero-out overhead doesn't +> get paid during normal operation. +> +> You do need metadata journaling for all non-WAL PG files, since we don't +> fsync them every time we extend them; which means the filesystem could +> lose track of which disk blocks belong to such a file, if it's not +> journaled. + +Thanks for the clarification! Nice to know I can setup an ext2 +partition for my WAL files then. Is this in the docs anywhere? + +From pgsql-performance-owner@postgresql.org Thu Nov 10 13:24:40 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id EBC26DAE49 + for ; + Thu, 10 Nov 2005 13:24:37 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 12429-10 + for ; + Thu, 10 Nov 2005 17:24:36 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 664CCDA5B3 + for ; + Thu, 10 Nov 2005 13:24:36 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAAHNKhH010165; + Thu, 10 Nov 2005 12:23:20 -0500 (EST) +To: Mitch Skinner +Cc: pgsql-performance@postgresql.org +Subject: Re: same plan, add 1 condition, 1900x slower +In-reply-to: <1131630176.29496.91.camel@enzian> +References: <1131630176.29496.91.camel@enzian> +Comments: In-reply-to Mitch Skinner + message dated "Thu, 10 Nov 2005 05:42:56 -0800" +Date: Thu, 10 Nov 2005 12:23:20 -0500 +Message-ID: <10164.1131643400@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/190 +X-Sequence-Number: 15447 + +Mitch Skinner writes: +> This is with Postgres 8.0.3. Any advice is appreciated. + +These are exactly the same plan, except for the addition of the extra +filter condition ... + +> -> Index Scan using external_id_map_primary_key on external_id_map +> eim (cost=0.00..2345747.01 rows=15560708 width=26) (actual +> time=0.061..2.944 rows=2175 loops=1) + +> -> Index Scan using external_id_map_primary_key on external_id_map +> eim (cost=0.00..2384648.78 rows=4150 width=26) (actual +> time=0.020..21068.508 rows=1186 loops=1) +> Filter: (source = 'SCH'::bpchar) + +Apparently, you are using a platform and/or locale in which strcoll() is +spectacularly, god-awfully slow --- on the order of 10 msec per comparison. +This is a bit hard to believe but I can't make sense of those numbers +any other way. What is the platform exactly, and what database locale +and encoding are you using? + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Thu Nov 10 13:44:21 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 453BCD7BAF + for ; + Thu, 10 Nov 2005 13:44:19 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 21804-01 + for ; + Thu, 10 Nov 2005 17:44:17 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 7A597D7115 + for ; + Thu, 10 Nov 2005 13:44:17 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAAHiFer010321; + Thu, 10 Nov 2005 12:44:16 -0500 (EST) +To: Scott Marlowe +Cc: Michael Stone , + pgsql-performance@postgresql.org +Subject: Re: WAL sync behaviour +In-reply-to: <1131642009.3554.87.camel@state.g2switchworks.com> +References: <20051110133241.GA4031@uio.no> <437355C6.4030604@archonet.com> + <20051110142535.GA4530@uio.no> <20051110144309.GO9905@mathom.us> + <1131637958.3554.75.camel@state.g2switchworks.com> + <9791.1131640774@sss.pgh.pa.us> + <1131642009.3554.87.camel@state.g2switchworks.com> +Comments: In-reply-to Scott Marlowe + message dated "Thu, 10 Nov 2005 11:00:10 -0600" +Date: Thu, 10 Nov 2005 12:44:15 -0500 +Message-ID: <10320.1131644655@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/191 +X-Sequence-Number: 15448 + +Scott Marlowe writes: +> Thanks for the clarification! Nice to know I can setup an ext2 +> partition for my WAL files then. Is this in the docs anywhere? + +Don't think so ... want to write something up? Hard part is to +figure out where to put it ... + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Thu Nov 10 13:58:51 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 80551DB1D0 + for ; + Thu, 10 Nov 2005 13:58:50 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 03722-10 + for ; + Thu, 10 Nov 2005 17:58:47 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from cassarossa.samfundet.no (cassarossa.samfundet.no + [129.241.93.19]) + by svr1.postgresql.org (Postfix) with ESMTP id 0C4B0DB178 + for ; + Thu, 10 Nov 2005 13:58:47 -0400 (AST) +Received: from trofast.ipv6.sesse.net ([2001:700:300:dc03:20e:cff:fe36:a766] + helo=trofast.sesse.net) + by cassarossa.samfundet.no with esmtp (Exim 4.50) id 1EaGhB-0002Jg-Kr + for pgsql-performance@postgresql.org; Thu, 10 Nov 2005 18:58:47 +0100 +Received: from sesse by trofast.sesse.net with local (Exim 3.36 #1 (Debian)) + id 1EaGh9-0001dr-00 + for ; Thu, 10 Nov 2005 18:58:43 +0100 +Date: Thu, 10 Nov 2005 18:58:43 +0100 +From: "Steinar H. Gunderson" +To: pgsql-performance@postgresql.org +Subject: Re: WAL sync behaviour +Message-ID: <20051110175843.GA6254@uio.no> +Mail-Followup-To: pgsql-performance@postgresql.org +References: <20051110133241.GA4031@uio.no> <437355C6.4030604@archonet.com> + <20051110142535.GA4530@uio.no> <20051110144309.GO9905@mathom.us> + <1131637958.3554.75.camel@state.g2switchworks.com> + <9791.1131640774@sss.pgh.pa.us> + <1131642009.3554.87.camel@state.g2switchworks.com> + <10320.1131644655@sss.pgh.pa.us> +MIME-Version: 1.0 +Content-Type: text/plain; charset=utf-8 +Content-Disposition: inline +In-Reply-To: <10320.1131644655@sss.pgh.pa.us> +X-Operating-System: Linux 2.6.14 on a i686 +X-Message-Flag: Outlook? --> http://www.mozilla.org/products/thunderbird/ +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.008 required=5 tests=[AWL=0.008] +X-Spam-Score: 0.008 +X-Spam-Level: +X-Archive-Number: 200511/192 +X-Sequence-Number: 15449 + +On Thu, Nov 10, 2005 at 12:44:15PM -0500, Tom Lane wrote: +> Don't think so ... want to write something up? Hard part is to +> figure out where to put it ... + +To be honest, I think we could use a "newbie's guide to PostgreSQL +performance tuning". I've seen rather good guides for query tuning, and +guides for general performance tuning, but none that really cover both in a +coherent way. (Also, many of the ones I've seen start getting rather dated; +after bitmap index scans arrived, for instance, many of the rules with regard +to index planning probably changed.) + +I'd guess http://www.powerpostgresql.com/PerfList is a rather good start for +the second part (and it's AFAICS under a free license); having something like +that in the docs (or some other document) would probably be a good start. + +/* Steinar */ +-- +Homepage: http://www.sesse.net/ + +From pgsql-performance-owner@postgresql.org Thu Nov 10 14:04:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 57C4ADB01E + for ; + Thu, 10 Nov 2005 14:04:43 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 39828-09 + for ; + Thu, 10 Nov 2005 18:04:41 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id D6DC9DAF1B + for ; + Thu, 10 Nov 2005 14:04:41 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAAI4fE6010462; + Thu, 10 Nov 2005 13:04:41 -0500 (EST) +To: Charlie Savage +Cc: pgsql-performance@postgresql.org +Subject: Re: Index Scan Costs versus Sort +In-reply-to: +References: +Comments: In-reply-to Charlie Savage + message dated "Thu, 10 Nov 2005 09:59:21 -0700" +Date: Thu, 10 Nov 2005 13:04:41 -0500 +Message-ID: <10461.1131645881@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/193 +X-Sequence-Number: 15450 + +Charlie Savage writes: +> 1. Postgresql estimates the index scan will be 50 times more costly +> than the seq scan (112870376 vs 2229858) yet in fact it only takes 3 +> times longer to execute (2312426 s vs. 768403 s). My understanding is +> that postgresql assumes, via the random_page_cost parameter, that an +> index scan will take 4 times longer than a sequential scan. So why is +> the analyzer estimating it is 50 times slower? + +The other factors that are likely to affect this are index correlation +and effective cache size. It's fairly remarkable that a full-table +index scan only takes 3 times longer than a seqscan; you must have both +a high correlation and a reasonably large cache. You showed us your +effective_cache_size setting, but what's the pg_stats entry for +completechain.tlid contain? Can you quantify what the physical +ordering of tlid values is likely to be? + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Thu Nov 10 14:17:37 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A0F64D9599 + for ; + Thu, 10 Nov 2005 14:17:35 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 68883-10 + for ; + Thu, 10 Nov 2005 18:17:33 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from brmea-mail-4.sun.com (brmea-mail-4.Sun.COM [192.18.98.36]) + by svr1.postgresql.org (Postfix) with ESMTP id D35CCD7CB7 + for ; + Thu, 10 Nov 2005 14:17:33 -0400 (AST) +Received: from phys-hanwk-1 ([129.149.2.111]) + by brmea-mail-4.sun.com (8.12.10/8.12.9) with ESMTP id jAAIHXD7000132 + for ; + Thu, 10 Nov 2005 11:17:33 -0700 (MST) +Received: from conversion-daemon.hanwk-mail1.sfbay.sun.com by + hanwk-mail1.sfbay.sun.com + (iPlanet Messaging Server 5.2 HotFix 1.24 (built Dec 19 2003)) + id <0IPR00B013ZUPV@hanwk-mail1.sfbay.sun.com> + (original mail from Ashok.Agrawal@Sun.COM) + for pgsql-performance@postgresql.org; + Thu, 10 Nov 2005 10:17:33 -0800 (PST) +Received: from Sun.COM (sr1-unwk-09.SFBay.Sun.COM [129.149.2.159]) + by hanwk-mail1.sfbay.sun.com + (iPlanet Messaging Server 5.2 HotFix 1.24 (built Dec 19 2003)) + with ESMTP id <0IPR008TV459LG@hanwk-mail1.sfbay.sun.com>; Thu, + 10 Nov 2005 10:17:33 -0800 (PST) +Date: Thu, 10 Nov 2005 10:17:33 -0800 +From: Ashok Agrawal +Subject: Re: Outer Join performance in PostgreSQL +In-reply-to: <87d5l9r1mm.fsf@hero.mallet-assembly.org> +To: Michael Alan Dorman +Cc: pgsql-performance@postgresql.org +Reply-To: Ashok.Agrawal@Sun.COM +Message-id: <43738EBD.1090507@Sun.COM> +MIME-version: 1.0 +Content-type: text/plain; charset=us-ascii +Content-transfer-encoding: 7BIT +X-Accept-Language: en-us, en +User-Agent: Mozilla/5.0 (X11; U; SunOS sun4u; en-US; rv:1.4) Gecko/20041214 +References: <43725511.3040809@Sun.COM> + <87d5l9r1mm.fsf@hero.mallet-assembly.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.053 required=5 tests=[AWL=0.052, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.053 +X-Spam-Level: +X-Archive-Number: 200511/194 +X-Sequence-Number: 15451 + +Hello Michael, + +Here is the information : I had executed explain analyze with modified +FROM clause. + +Oops forgot to mention the version earlier. + +Using postgres 8.0.0 on Solaris 9. + +Rows Count : + +cic=# select count(*) from taxpack_user; + count +-------- + 172645 +(1 row) + +cic=# select count(*) from ecms_certificate_types; + count +------- + 10 +(1 row) + +cic=# select count(*) from ecms_cert_headers; + count +------- + 17913 +(1 row) + +Table Information : + + Table "ecms.ecms_certificate_types" + Column | Type | Modifiers +------------------------------+-----------------------------+----------- + certificate_type_id | smallint | not null + certificate_type_description | character varying(60) | + created_by | character varying(30) | + created_date | timestamp without time zone | + updated_by | character varying(30) | + updated_date | timestamp without time zone | +Indexes: + "sys_c003733" PRIMARY KEY, btree (certificate_type_id) + "pk_ecms_certificate_types" UNIQUE, btree (certificate_type_id) + + Table "ecms.ecms_cert_headers" + Column | Type | Modifiers +---------------------+-----------------------------+----------- + dln_code | character varying(10) | not null + sun_legal_entity | character varying(12) | not null + other_entity_name | character varying(20) | + company_name | character varying(80) | not null + certificate_date | timestamp without time zone | not null + certificate_type_id | smallint | not null + description | character varying(80) | not null + blanket_single | character(1) | not null + notes | character varying(4000) | + certificate_status | character(1) | not null + approved_by | character varying(30) | + approved_date | timestamp without time zone | + created_by | character varying(30) | + created_date | timestamp without time zone | + updated_by | character varying(30) | + updated_date | timestamp without time zone | +Indexes: + "pk_ecms_cert_headers" UNIQUE, btree (dln_code) + "ecms_cert_headers_idx1" btree (certificate_type_id) + "ecms_cert_headers_idx2" btree (company_name) + "ecms_cert_headers_idx3" btree (description) +Foreign-key constraints: + "sys_c003754" FOREIGN KEY (certificate_type_id) REFERENCES +ecms_certificate_types(certificate_type_id) + + Table "ecms.taxpack_user" + Column | Type | Modifiers +------------+-----------------------+----------- + emp_no | character varying(12) | not null + name | character varying(60) | not null + manager_id | character varying(12) | + dept_no | character varying(12) | + mailstop | character varying(12) | + phone | character varying(60) | + email | character varying(60) | + active | character varying(3) | not null + admin | smallint | not null + super_user | smallint | not null + + +Merge Right Join (cost=1757437.54..21072796.15 rows=643816513 width=874) +(actual time=27800.250..27800.256 rows=1 loops=1) + Merge Cond: ("outer"."?column3?" = "inner"."?column17?") + -> Sort (cost=30776.19..31207.80 rows=172645 width=64) (actual +time=12229.482..12791.468 rows=172645 loops=1) + Sort Key: (e.emp_no)::text + -> Seq Scan on taxpack_user e (cost=0.00..4898.45 rows=172645 +width=64) (actual time=0.050..1901.218 rows=172645 loops=1) + -> Sort (cost=1726661.35..1728525.92 rows=745827 width=859) (actual +time=12675.899..12675.901 rows=1 loops=1) + Sort Key: (a.approved_by)::text + -> Merge Left Join (cost=29219.87..40411.59 rows=745827 width=859) +(actual time=12675.815..12675.830 rows=1 loops=1) + Merge Cond: ("outer"."?column18?" = "inner"."?column2?") + -> Sort (cost=7106.77..7108.93 rows=864 width=892) (actual +time=1441.644..1441.646 rows=1 loops=1) + Sort Key: (a.updated_by)::text + -> Nested Loop Left Join (cost=0.00..7064.62 rows=864 +width=892) (actual time=435.864..1441.465 rows=1 loops=1) + Join Filter: (("outer".created_by)::text = +("inner".emp_no)::text) + -> Nested Loop Left Join (cost=0.00..8.11 rows=1 +width=877) (actual time=0.251..0.361 rows=1 loops=1) + Join Filter: ("outer".certificate_type_id = +"inner".certificate_type_id) + -> Index Scan using pk_ecms_cert_headers on +ecms_cert_headers a (cost=0.00..6.01 rows=1 width=829) (actual +time=0.113..0.136 rows=1 loops=1) + Index Cond: ((dln_code)::text = +'17319'::text) + -> Seq Scan on ecms_certificate_types b +(cost=0.00..1.49 rows=49 width=50) (actual time=0.018..0.059 rows=10 loops=1) + -> Seq Scan on taxpack_user c (cost=0.00..4898.45 +rows=172645 width=64) (actual time=0.014..674.881 rows=172645 loops=1) + -> Sort (cost=22113.10..22544.71 rows=172645 width=16) (actual +time=10689.742..10885.155 rows=71665 loops=1) + Sort Key: (d.emp_no)::text + -> Seq Scan on taxpack_user d (cost=0.00..4898.45 +rows=172645 width=16) (actual time=0.031..1791.036 rows=172645 loops=1) + Total runtime: 27802.014 ms +(23 rows) + + + +Michael Alan Dorman wrote On 11/09/05 12:45,: +> Ashok Agrawal writes: +> +>>I noticed outer join is very very slow in postgresql as compared +>>to Oracle. +> +> +> I think the three things the people best able to help you are going to +> ask for are 1) what version of PostgreSQL, 2) what are the tables, and +> how many rows in each, and 3) output from 'explain analyze' rather +> than just 'explain'. +> +> That said, I'm willing to take an amateurish stab at it even without +> that. +> +> In fact, I don't think the outer joins are the issue at all. I see +> that you're forcing a right join from ecms_certificate_types to +> ecms_cert_headers. This seems to be causing postgresql to think it +> must (unnecessarily) consider three quarters of a billion rows, which, +> if I'm reading right, seems to be producing the majority of the +> estimated cost: +> +> +>> Hash Join (cost=1666049.74..18486619.37 rows=157735046 width=874) +>> Hash Cond: ("outer".certificate_type_id = "inner".certificate_type_id) +>> -> Merge Right Join (cost=1666048.13..11324159.05 rows=643816513 width=826) +> +> +> In fact, looking at the fact that you're doing a COALESCE on a column +> from b, it seems to me that doing a right join from ecms_cert_headers +> to ecms_certificate_types is just wrong. It seems to me that that +> should be a left join as well. +> +> With that in mind, I would rewrite the whole FROM clause as: +> +> FROM ecms_cert_headers a +> LEFT OUTER JOIN ecms_certificate_types b +> ON (a.certificate_type_id = b.certificate_type_id) +> LEFT OUTER JOIN taxpack_user c +> ON (a.created_by = c.emp_no) +> LEFT OUTER JOIN taxpack_user d +> ON (a.updated_by = d.emp_no) +> LEFT OUTER JOIN taxpack_user e +> ON (a.approved_by = e.emp_no) +> WHERE a.dln_code = '17319' +> +> It seems to me that this more reflects the intent of the data that is +> being retrieved. I would also expect it to be a boatload faster. +> +> Assuming I've understood the intent correctly, I would guess that the +> difference is the result of the Oracle planner being able to eliminate +> the right join or something. +> +> Mike +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 4: Have you searched our list archives? +> +> http://archives.postgresql.org + +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +NOTICE: This email message is for the sole use of the intended +recipient(s) and may contain confidential and privileged +information. Any unauthorized review, use, disclosure or +distribution is prohibited. If you are not the intended +recipient, please contact the sender by reply email and destroy +all copies of the original message. +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + + +From pgsql-performance-owner@postgresql.org Thu Nov 10 15:01:02 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 3AB61DAF90 + for ; + Thu, 10 Nov 2005 15:01:01 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 88555-08 + for ; + Thu, 10 Nov 2005 19:00:59 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id CE795DAF13 + for ; + Thu, 10 Nov 2005 15:00:58 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id D486E31059; Thu, 10 Nov 2005 20:00:58 +0100 (MET) +From: Charlie Savage +X-Newsgroups: pgsql.performance +Subject: Re: Index Scan Costs versus Sort +Date: Thu, 10 Nov 2005 12:00:51 -0700 +Organization: Hub.Org Networking Services +Lines: 56 +Message-ID: <437398E3.2020900@interserv.com> +References: <10461.1131645881@sss.pgh.pa.us> +Mime-Version: 1.0 +Content-Type: text/plain; charset=UTF-8; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +To: Tom Lane +User-Agent: Thunderbird 1.5 (Windows/20051025) +In-Reply-To: <10461.1131645881@sss.pgh.pa.us> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/195 +X-Sequence-Number: 15452 + +Hi Tom, + + From pg_stats: + +schema = "tiger"; +tablename = "completechain"; +attname = "tlid"; +null_frac = 0; +avg_width = 4; +n_distinct = -1; +most_common_vals = ; +most_common_freqs = ; +correlation = 0.155914; + +Note that I have default_statistics_target set to 100. Here is the +first few values from histogram_bounds: + +"{102450,2202250,4571797,6365754,8444936,10541593,12485818,14545727,16745594,18421868,20300549,22498643,24114709,26301001,28280632,30370123,32253657,33943046,35898115,37499478,39469054,41868498,43992143,45907830,47826340,49843926,52051798,54409298,56447416, + + +The tlid column is a US Census bureau ID assigned to each chain in the +US - where a chain is a road segment, river segment, railroad segment, +etc. The data is loaded on state-by-state basis, and then a +county-by-county basis. There is no overall ordering to TLIDs, although +perhaps there is some local ordering at the county level (but from a +quick look at the data I don't see any, and the correlation factor +indicates there isn't any if I am interpreting it correctly). + +Any other info that would be helpful to see? + + +Charlie + + +Tom Lane wrote: +> Charlie Savage writes: +>> 1. Postgresql estimates the index scan will be 50 times more costly +>> than the seq scan (112870376 vs 2229858) yet in fact it only takes 3 +>> times longer to execute (2312426 s vs. 768403 s). My understanding is +>> that postgresql assumes, via the random_page_cost parameter, that an +>> index scan will take 4 times longer than a sequential scan. So why is +>> the analyzer estimating it is 50 times slower? +> +> The other factors that are likely to affect this are index correlation +> and effective cache size. It's fairly remarkable that a full-table +> index scan only takes 3 times longer than a seqscan; you must have both +> a high correlation and a reasonably large cache. You showed us your +> effective_cache_size setting, but what's the pg_stats entry for +> completechain.tlid contain? Can you quantify what the physical +> ordering of tlid values is likely to be? +> +> regards, tom lane +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 5: don't forget to increase your free space map settings +> + +From pgsql-performance-owner@postgresql.org Thu Nov 10 16:46:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0C65FD7115 + for ; + Thu, 10 Nov 2005 16:46:48 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 49664-02 + for ; + Thu, 10 Nov 2005 20:46:45 +0000 (GMT) +X-Greylist: delayed 00:06:43.707071 by SQLgrey- +Received: from tbmail.tradebot.com + (Tradebot-Systems-1096753.cust-rtr.swbell.net [68.90.170.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 811C3D70C0 + for ; + Thu, 10 Nov 2005 16:46:46 -0400 (AST) +Received: from 192.168.200.29 ([192.168.200.29]) by tbmail.tradebot.com + ([192.168.1.50]) with Microsoft Exchange Server HTTP-DAV ; + Thu, 10 Nov 2005 20:46:48 +0000 +Received: from krb06 by TBMAIL; 10 Nov 2005 14:46:48 -0600 +Subject: Re: 8.x index insert performance +From: Kelly Burkhart +To: Ron Peacetree +Cc: pgsql-performance@postgresql.org +In-Reply-To: + <867256.1130859455220.JavaMail.root@elwamui-norfolk.atl.sa.earthlink.net> +References: + <867256.1130859455220.JavaMail.root@elwamui-norfolk.atl.sa.earthlink.net> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Thu, 10 Nov 2005 14:46:48 -0600 +Message-Id: <1131655608.7514.51.camel@krb06.tradebot.com> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.1 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.02 required=5 tests=[AWL=0.019, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.02 +X-Spam-Level: +X-Archive-Number: 200511/196 +X-Sequence-Number: 15453 + +On Tue, 2005-11-01 at 10:37 -0500, Ron Peacetree wrote: +> I'm surprised that no one seems to have yet suggested the following +> simple experiment: +> +> Increase the RAM 4GB -> 8GB, tune for best performance, and +> repeat your 100M row insert experiment. +> +> Does overall insert performance change? Does the performance +> drop rows in still occur? Does it occur in ~ the same place? +> Etc. +> +> If the effect does seem to be sensitive to the amount of RAM in the +> server, it might be worth redoing the experiment(s) with 2GB and +> 16GB as well... + +Ron, + +I would like to try this, however, since I'm sitting about 1000 miles +away from the server, tweaking things is not as simple as one might +hope. I would also like to understand what is going on before I start +changing things. If I can't get a satisfactory explanation for what I'm +seeing with current hardware, I'll have memory added and see what +happens. + +-K + +From pgsql-performance-owner@postgresql.org Thu Nov 10 18:01:58 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 487BBD7115 + for ; + Thu, 10 Nov 2005 18:01:57 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 64127-06 + for ; + Thu, 10 Nov 2005 22:01:54 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from tbmail.tradebot.com + (Tradebot-Systems-1096753.cust-rtr.swbell.net [68.90.170.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 442C4D70C0 + for ; + Thu, 10 Nov 2005 18:01:54 -0400 (AST) +Received: from 192.168.200.29 ([192.168.200.29]) by tbmail.tradebot.com + ([192.168.1.50]) with Microsoft Exchange Server HTTP-DAV ; + Thu, 10 Nov 2005 22:01:57 +0000 +Received: from krb06 by TBMAIL; 10 Nov 2005 16:01:57 -0600 +Subject: Re: 8.x index insert performance +From: Kelly Burkhart +To: pgsql-performance@postgresql.org +In-Reply-To: <24845.1130852730@sss.pgh.pa.us> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD725@Herge.rcsinc.local> + <20051031193547.GA3311@mark.mielke.cc> <18647.1130790629@sss.pgh.pa.us> + <1130792391.7026.55.camel@krb06.tradebot.com> + <19065.1130793527@sss.pgh.pa.us> + <1130852029.7026.88.camel@krb06.tradebot.com> + <24845.1130852730@sss.pgh.pa.us> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Thu, 10 Nov 2005 16:01:57 -0600 +Message-Id: <1131660117.7514.57.camel@krb06.tradebot.com> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.1 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.018 required=5 tests=[AWL=0.017, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.018 +X-Spam-Level: +X-Archive-Number: 200511/197 +X-Sequence-Number: 15454 + +Second try... no attachment this time. + +I've finally gotten around to profiling the back end. Here is a more +precise description of what I'm doing: + +I am copying data into two tables, order_main and order_transition +(table defs at the end of this post). The order_transition table has +roughly double the number of rows as the order_main table. + +My program is a C program using the libpq copy api which effectively +simulates our real application. It reads data from two data files, and +appends copy-formatted data into two in-memory buffers. After 10,000 +order_transitions, it copies the order_main data, then the +order_transition data, then commits. The test program is running on a +different machine than the DB. + +After each batch it writes a record to stdout with the amount of time it +took to copy and commit the data (time only includes pg time, not the +time it took to build the buffers). A graph showing the performance +characteristics is here: + + + +The horizontal axis is number of transitions * 10000 that have been +written. The vertical axis is time in milliseconds to copy and commit +the data. The commit time is very consistent up until about 60,000,000 +rows, then performance drops and times become much less consistent. + +I profiled the backend at three points, on batches 4, 6042 and 6067. +The first is right after start, the second is right before we hit the +wall, and the third is one of the initial slow batches. + +I'm including inline the first 20 lines of gprof output for each batch. +Please let me know if this is insufficient. I'll supply any necessary +further info. + +Since this thread is stale, I'll repeat relevant hardware/software +stats: server is a dual, dual-core opteron with 4GB RAM. Disk is an +EMC Symmetrix connected via FC. Data, index, logs on three separate +LUNS. OS is SuSE Enterprise 9. Postgres version is 8.1.b4. +shared_buffers=32768, fsync=off. + +Thanks in advance for your help. + +-K + +--------------------------- +> head -n 20 gprof.txt.4.777.47 +Flat profile: + +Each sample counts as 0.01 seconds. + % cumulative self self total + time seconds seconds calls s/call s/call name + 10.92 0.38 0.38 55027 0.00 0.00 XLogInsert + 6.90 0.62 0.24 702994 0.00 0.00 _bt_compare + 5.46 0.81 0.19 2 0.10 1.64 DoCopy + 4.60 0.97 0.16 16077 0.00 0.00 CopyReadLine + 3.74 1.10 0.13 484243 0.00 0.00 bttextcmp + 2.87 1.20 0.10 93640 0.00 0.00 _bt_binsrch + 2.59 1.29 0.09 484243 0.00 0.00 varstr_cmp + 2.59 1.38 0.09 364292 0.00 0.00 LWLockRelease + 2.30 1.46 0.08 703394 0.00 0.00 FunctionCall2 + 2.01 1.53 0.07 138025 0.00 0.00 hash_any + 2.01 1.60 0.07 133176 0.00 0.00 ReadBuffer + 2.01 1.67 0.07 364110 0.00 0.00 LWLockAcquire + 2.01 1.74 0.07 132563 0.00 0.00 PinBuffer + 1.72 1.80 0.06 38950 0.00 0.00 _bt_insertonpg + 1.72 1.86 0.06 38767 0.00 0.00 _bt_mkscankey + +--------------------------- +> head -n 20 gprof.txt.6042.1344.84 +Flat profile: + +Each sample counts as 0.01 seconds. + % cumulative self self total + time seconds seconds calls s/call s/call name + 9.67 0.52 0.52 50431 0.00 0.00 XLogInsert + 7.71 0.94 0.42 1045427 0.00 0.00 _bt_compare + 5.95 1.26 0.32 713392 0.00 0.00 bttextcmp + 4.28 1.49 0.23 1045814 0.00 0.00 FunctionCall2 + 3.35 1.67 0.18 155756 0.00 0.00 _bt_binsrch + 2.60 1.81 0.14 713392 0.00 0.00 varstr_cmp + 2.60 1.95 0.14 475524 0.00 0.00 LWLockAcquire + 2.60 2.09 0.14 191837 0.00 0.00 ReadBuffer + 2.60 2.23 0.14 2 0.07 2.52 DoCopy + 2.60 2.37 0.14 197393 0.00 0.00 hash_search + 2.60 2.51 0.14 197205 0.00 0.00 hash_any + 2.23 2.63 0.12 190481 0.00 0.00 PinBuffer + 2.04 2.74 0.11 345866 0.00 0.00 AllocSetAlloc + 1.86 2.84 0.10 475788 0.00 0.00 LWLockRelease + 1.86 2.94 0.10 29620 0.00 0.00 pg_localtime + +--------------------------- +> head -n 20 gprof.txt.6067.9883.31 +Flat profile: + +Each sample counts as 0.01 seconds. + % cumulative self self total + time seconds seconds calls s/call s/call name + 17.17 1.14 1.14 51231 0.00 0.00 XLogInsert + 10.82 1.85 0.72 1065556 0.00 0.00 _bt_compare + 4.77 2.17 0.32 158378 0.00 0.00 _bt_binsrch + 3.18 2.38 0.21 202921 0.00 0.00 hash_search + 3.18 2.59 0.21 742891 0.00 0.00 bttextcmp + 2.87 2.78 0.19 1485787 0.00 0.00 pg_detoast_datum + 2.87 2.97 0.19 1065325 0.00 0.00 FunctionCall2 + 2.65 3.14 0.18 490373 0.00 0.00 LWLockAcquire + 2.27 3.29 0.15 2 0.08 3.08 DoCopy + 2.27 3.44 0.15 490908 0.00 0.00 LWLockRelease + 1.97 3.57 0.13 195049 0.00 0.00 ReadBuffer + 1.97 3.70 0.13 742891 0.00 0.00 varstr_cmp + 1.66 3.81 0.11 462134 0.00 0.00 LockBuffer + 1.51 3.91 0.10 191345 0.00 0.00 PinBuffer + 1.51 4.01 0.10 195049 0.00 0.00 UnpinBuffer + +--------------------------- +create table order_main ( + ord_id varchar(12) not null, + firm_id varchar not null, + firm_sub_id varchar not null, + cl_ord_id varchar not null, + clearing_firm varchar not null, + clearing_account varchar not null, + symbol varchar not null, + side varchar(1) not null, + size integer not null, + price numeric(10,4) not null, + expire_time timestamp with time zone, + flags varchar(7) not null +); + +create unique index order_main_pk on order_main ( + ord_id +) tablespace idx_space; + +create index order_main_ak1 on order_main ( + cl_ord_id +) tablespace idx_space; + + +create table order_transition ( + collating_seq bigint not null, + ord_id varchar(12) not null, + cl_ord_id varchar, + sending_time timestamp with time zone not null, + transact_time timestamp with time zone not null, + flags varchar(6) not null, + exec_id varchar(12), + size integer, + price numeric(10,4), + remainder integer, + contra varchar +); + +create unique index order_transition_pk on order_transition ( + collating_seq +) tablespace idx_space; + +create index order_transition_ak1 on order_transition ( + ord_id +) tablespace idx_space; + +create index order_transition_ak2 on order_transition ( + cl_ord_id +) +tablespace idx_space +where cl_ord_id is not null; + +create index order_transition_ak3 on order_transition ( + exec_id +) +tablespace idx_space +where exec_id is not null; + + + +From pgsql-performance-owner@postgresql.org Thu Nov 10 18:18:14 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0ED23D7B75 + for ; + Thu, 10 Nov 2005 18:18:13 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 71779-09 + for ; + Thu, 10 Nov 2005 22:18:10 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id BFEFBD7115 + for ; + Thu, 10 Nov 2005 18:18:11 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAAMIE1T012267; + Thu, 10 Nov 2005 17:18:14 -0500 (EST) +To: Kelly Burkhart +Cc: pgsql-performance@postgresql.org +Subject: Re: 8.x index insert performance +In-reply-to: <1131655202.7514.46.camel@krb06.tradebot.com> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD725@Herge.rcsinc.local> + <20051031193547.GA3311@mark.mielke.cc> + <18647.1130790629@sss.pgh.pa.us> + <1130792391.7026.55.camel@krb06.tradebot.com> + <19065.1130793527@sss.pgh.pa.us> + <1130852029.7026.88.camel@krb06.tradebot.com> + <24845.1130852730@sss.pgh.pa.us> + <1131655202.7514.46.camel@krb06.tradebot.com> +Comments: In-reply-to Kelly Burkhart + message dated "Thu, 10 Nov 2005 14:40:02 -0600" +Date: Thu, 10 Nov 2005 17:18:14 -0500 +Message-ID: <12266.1131661094@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/198 +X-Sequence-Number: 15455 + +Kelly Burkhart writes: +> I've finally gotten around to profiling the back end. + +Thanks for following up. + +The sudden appearance of pg_detoast_datum() in the top ten in the third +profile is suspicious. I wouldn't expect that to get called at all, +really, during a normal COPY IN process. The only way I can imagine it +getting called is if you have index entries that require toasting, which +seems a bit unlikely to start happening only after 60 million rows. +Is it possible that the index keys are getting longer and longer as your +test run proceeds? + +Could you send me (off list) the complete gprof output files? + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Thu Nov 10 19:01:39 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 36266D7B75 + for ; + Thu, 10 Nov 2005 19:01:38 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 79334-10 + for ; + Thu, 10 Nov 2005 23:01:34 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id A7C30D70C0 + for ; + Thu, 10 Nov 2005 19:01:35 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAAN1ckG012583; + Thu, 10 Nov 2005 18:01:38 -0500 (EST) +To: Kelly Burkhart +Cc: pgsql-performance@postgresql.org +Subject: Re: 8.x index insert performance +In-reply-to: <1131662056.7514.61.camel@krb06.tradebot.com> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD725@Herge.rcsinc.local> + <20051031193547.GA3311@mark.mielke.cc> + <18647.1130790629@sss.pgh.pa.us> + <1130792391.7026.55.camel@krb06.tradebot.com> + <19065.1130793527@sss.pgh.pa.us> + <1130852029.7026.88.camel@krb06.tradebot.com> + <24845.1130852730@sss.pgh.pa.us> + <1131655202.7514.46.camel@krb06.tradebot.com> + <12266.1131661094@sss.pgh.pa.us> + <1131662056.7514.61.camel@krb06.tradebot.com> +Comments: In-reply-to Kelly Burkhart + message dated "Thu, 10 Nov 2005 16:34:16 -0600" +Date: Thu, 10 Nov 2005 18:01:38 -0500 +Message-ID: <12582.1131663698@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/199 +X-Sequence-Number: 15456 + +Kelly Burkhart writes: +> On Thu, 2005-11-10 at 17:18 -0500, Tom Lane wrote: +>> Could you send me (off list) the complete gprof output files? + +> Sure, + +Thanks. Right offhand I can see no smoking gun here. The +pg_detoast_datum entry I was worried about seems to be just measurement +noise --- the gprof trace shows that it's called a proportional number +of times in both cases, and it falls through without actually doing +anything in all cases. + +The later trace involves a slightly larger amount of time spent +inserting into the indexes, which is what you'd expect as the indexes +get bigger, but it doesn't seem that CPU time per se is the issue. +The just-before-the-cliff trace shows total CPU of 5.38 sec and the +after-the-cliff one shows 6.61 sec. + +What I now suspect is happening is that you "hit the wall" at the point +where the indexes no longer fit into main memory and it starts taking +significant I/O to search and update them. Have you tried watching +iostat or vmstat output to see if there's a noticeable increase in I/O +at the point where things slow down? Can you check the physical size of +the indexes at that point, and see if it seems related to your available +RAM? + +If that is the correct explanation, then the only solutions I can see +are (1) buy more RAM or (2) avoid doing incremental index updates; +that is, drop the indexes before bulk load and rebuild them afterwards. + +One point to consider is that an index will be randomly accessed only +if its data is being loaded in random order. If you're loading keys in +sequential order then only the "right-hand edge" of the index would get +touched, and it wouldn't need much RAM. So, depending on what order +you're loading data in, the primary key index may not be contributing +to the problem. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Thu Nov 10 20:11:56 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D398ADB250 + for ; + Thu, 10 Nov 2005 20:11:55 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 01894-06 + for ; + Fri, 11 Nov 2005 00:11:52 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id DD7FFD7115 + for ; + Thu, 10 Nov 2005 20:11:53 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id CE6EC31059; Fri, 11 Nov 2005 01:11:55 +0100 (MET) +From: Charlie Savage +X-Newsgroups: pgsql.performance +Subject: Re: Index Scan Costs versus Sort +Date: Thu, 10 Nov 2005 17:11:48 -0700 +Organization: Hub.Org Networking Services +Lines: 33 +Message-ID: +References: <10461.1131645881@sss.pgh.pa.us> + <437398E3.2020900@interserv.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=UTF-8; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +User-Agent: Thunderbird 1.5 (Windows/20051025) +In-Reply-To: <437398E3.2020900@interserv.com> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/200 +X-Sequence-Number: 15457 + +Following up with some additional information. + +The machine has 1Gb physical RAM. When I run the query (with sort and +seqscan enabled), top reports (numbers are fairly consistent): + +Mem: 1,032,972k total, 1,019,516k used, 13,412k free, 17,132k buffers + +Swap: 2,032,140k total, 17,592k used, 2,014,548k free, 742,636k cached + +The postmaster process is using 34.7% of RAM - 359m virt, 349 res, 319m. + No other process is using more than 2% of the memory. + + From vmstat: + +r b swpd free buff cache +1 0 17592 13568 17056 743676 + +vmstat also shows no swapping going on. + +Note that I have part of the database, for just Colorado, on my Windows +XP laptop (table size for completechain table in this case is 1Gb versus +18Gb for the whole US) for development purposes. I see the same +behavior on it, which is a Dell D6100 laptop with 1Gb, running 8.1, and +a default postgres.conf file with three changes (shared_buffers set to +7000, and work_mem set to 8192, effective_cache_size 2500). + +Out of curiosity, how much longer would an index_scan expected to be +versus a seq scan? I was under the impression it would be about a facto +of 4, or is that not usually the case? + +Thanks for the help, + +Charlie + +From pgsql-performance-owner@postgresql.org Thu Nov 10 20:13:27 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id C076BDB259 + for ; + Thu, 10 Nov 2005 20:13:26 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 07776-04 + for ; + Fri, 11 Nov 2005 00:13:23 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 3372CDB250 + for ; + Thu, 10 Nov 2005 20:13:25 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAB0DSW6013168; + Thu, 10 Nov 2005 19:13:28 -0500 (EST) +To: Kelly Burkhart +Cc: pgsql-performance@postgresql.org +Subject: Re: 8.x index insert performance +In-reply-to: <1131660117.7514.57.camel@krb06.tradebot.com> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD725@Herge.rcsinc.local> + <20051031193547.GA3311@mark.mielke.cc> + <18647.1130790629@sss.pgh.pa.us> + <1130792391.7026.55.camel@krb06.tradebot.com> + <19065.1130793527@sss.pgh.pa.us> + <1130852029.7026.88.camel@krb06.tradebot.com> + <24845.1130852730@sss.pgh.pa.us> + <1131660117.7514.57.camel@krb06.tradebot.com> +Comments: In-reply-to Kelly Burkhart + message dated "Thu, 10 Nov 2005 16:01:57 -0600" +Date: Thu, 10 Nov 2005 19:13:28 -0500 +Message-ID: <13167.1131668008@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/201 +X-Sequence-Number: 15458 + +Kelly Burkhart writes: +> ... A graph showing the performance +> characteristics is here: + +> + +I hadn't looked at this chart till just now, but it sure seems to put a +crimp in my theory that you are running out of room to hold the indexes +in RAM. That theory would predict that once you fall over the knee of +the curve, performance would get steadily worse; instead it gets +markedly worse and then improves a bit. And there's another cycle of +worse-and-better around 80M rows. I have *no* idea what's up with that. +Anyone? Kelly, could there be any patterns in the data that might be +related? + +The narrow spikes look like they are probably induced by checkpoints. +You could check that by seeing if their spacing changes when you alter +checkpoint_segments and checkpoint_timeout. It might also be +entertaining to make the bgwriter parameters more aggressive to see +if you can ameliorate the spikes. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Thu Nov 10 20:32:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CFACADB2BB + for ; + Thu, 10 Nov 2005 20:32:45 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 11431-07 + for ; + Fri, 11 Nov 2005 00:32:42 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 175FCDB2ED + for ; + Thu, 10 Nov 2005 20:32:43 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAB0Wkim013276; + Thu, 10 Nov 2005 19:32:46 -0500 (EST) +To: Charlie Savage +Cc: pgsql-performance@postgresql.org +Subject: Re: Index Scan Costs versus Sort +In-reply-to: +References: <10461.1131645881@sss.pgh.pa.us> + <437398E3.2020900@interserv.com> +Comments: In-reply-to Charlie Savage + message dated "Thu, 10 Nov 2005 17:11:48 -0700" +Date: Thu, 10 Nov 2005 19:32:46 -0500 +Message-ID: <13275.1131669166@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/202 +X-Sequence-Number: 15459 + +Charlie Savage writes: +> Out of curiosity, how much longer would an index_scan expected to be +> versus a seq scan? I was under the impression it would be about a facto +> of 4, or is that not usually the case? + +No, it can easily be dozens or even hundreds of times worse, in the +worst case. The factor of 4 you are thinking of is the random_page_cost +which is the assumed ratio between the cost of randomly fetching a page +and the cost of fetching it in a sequential scan of the whole table. +Not only is the sequential scan fetch normally much cheaper (due to less +seeking and the kernel probably catching on and doing read-ahead), but +if there are N tuples on a page then a seqscan reads them all with one +page fetch. In the worst case an indexscan might fetch the page from +disk N separate times, if all its tuples are far apart in the index +order. This is all on top of the extra cost to read the index itself, +too. + +The planner's estimate of 50x higher cost is not out of line for small +tuples (large N) and a badly-out-of-order table. What's puzzling is +that you seem to be getting near best-case behavior in what does not +seem to be a best-case scenario for an indexscan. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 11 05:17:18 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0CE17D6D4F + for ; + Fri, 11 Nov 2005 05:17:17 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 30057-03 + for ; + Fri, 11 Nov 2005 09:17:12 +0000 (GMT) +X-Greylist: delayed 19:34:22.308673 by SQLgrey- +Received: from mail2.egcrc.net (63-193-204-9.egcrc.org [63.193.204.9]) + by svr1.postgresql.org (Postfix) with ESMTP id 50A32D6D46 + for ; + Fri, 11 Nov 2005 05:17:12 -0400 (AST) +Received: from egcrc-ex01.egcrc.org ([172.16.1.4]) by mail2.egcrc.net with + Microsoft SMTPSVC(6.0.3790.211); Fri, 11 Nov 2005 01:17:13 -0800 +Received: from 172.16.0.166 ([172.16.0.166]) by egcrc-ex01.egcrc.org + ([172.16.1.4]) with Microsoft Exchange Server HTTP-DAV ; + Fri, 11 Nov 2005 09:17:12 +0000 +Received: from enzian by egcrc-ex01.egcrc.org; 11 Nov 2005 01:17:15 -0800 +Subject: Re: same plan, add 1 condition, 1900x slower +From: Mitch Skinner +To: Tom Lane +Cc: pgsql-performance@postgresql.org +In-Reply-To: <10164.1131643400@sss.pgh.pa.us> +References: <1131630176.29496.91.camel@enzian> + <10164.1131643400@sss.pgh.pa.us> +Content-Type: multipart/mixed; boundary="=-hgMMVV2ifun8oB6Cmlku" +Date: Fri, 11 Nov 2005 01:17:15 -0800 +Message-Id: <1131700635.29496.136.camel@enzian> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) +X-OriginalArrivalTime: 11 Nov 2005 09:17:13.0247 (UTC) + FILETIME=[B39CA2F0:01C5E6A0] +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/203 +X-Sequence-Number: 15460 + + +--=-hgMMVV2ifun8oB6Cmlku +Content-Type: text/plain +Content-Transfer-Encoding: 7bit + +On Thu, 2005-11-10 at 12:23 -0500, Tom Lane wrote: +> Apparently, you are using a platform and/or locale in which strcoll() is +> spectacularly, god-awfully slow --- on the order of 10 msec per comparison. + +The version with the condition is definitely doing more I/O. The +version without the condition doesn't read at all. I strace'd an +explain analyze for each separately, and this is what I ended up with +(the first is with the condition, the second is without): + +bash-2.05b$ cut '-d(' -f1 subsourcestrace | sort | uniq -c + 7127 gettimeofday + 75213 _llseek + 1 Process 30227 attached - interrupt to quit + 1 Process 30227 detached + 148671 read + 2 recv + 4 semop + 4 send +bash-2.05b$ cut '-d(' -f1 subsourcestrace-nocond | sort | uniq -c + 9103 gettimeofday + 7 _llseek + 1 Process 30227 attached - interrupt to quit + 1 Process 30227 detached + 2 recv + 4 send + +For the moment, all of the rows in the view I'm selecting from satisfy +the condition, so the output of both queries is the same. The relevant +rows of the underlying tables are probably pretty contiguous (all of the +rows satisfying the condition and the join were inserted at the same +time). Could it just be the result of a weird physical distribution of +data in the table/index files? For the fast query, the actual number of +rows is a lot less than the planner expects. + +> This is a bit hard to believe but I can't make sense of those numbers +> any other way. What is the platform exactly, and what database locale +> and encoding are you using? + +It's RHEL 3 on x86: +[root@rehoboam root]# uname -a +Linux rehoboam 2.4.21-32.0.1.ELsmp #1 SMP Tue May 17 17:52:23 EDT 2005 +i686 i686 i386 GNU/Linux + +The glibc version is 2.3.2. + +statgen=# select current_setting('lc_collate'); + current_setting +----------------- + en_US.UTF-8 + +Not sure what's relevant, but here's some more info: +The machine has 4.5GiB of RAM and a 5-disk Raid 5. It's a dual xeon +3.2ghz. + + relname | relpages | reltuples +-----------------------------+----------+------------- + external_id_map | 126883 | 1.55625e+07 + external_id_map_primary_key | 64607 | 1.55625e+07 + subject | 31 | 1186 + subject_pkey | 19 | 1186 + +I've attached the output of "select name, setting from pg_settings". + +And, in case my original message isn't handy, the explain analyze output +and table/view info is below. + +Thanks for taking a look, +Mitch + +statgen=> explain analyze select * from subject_source; + +QUERY PLAN +------------------------------------------------------------------------------------------------------------------------------------------------------------------------ + Merge Join (cost=0.00..330.72 rows=1186 width=46) (actual +time=0.051..8.890 rows=1186 loops=1) + Merge Cond: ("outer".id = "inner".target_id) + -> Index Scan using subject_pkey on subject norm (cost=0.00..63.36 +rows=1186 width=28) (actual time=0.022..1.441 rows=1186 loops=1) + -> Index Scan using external_id_map_primary_key on external_id_map +eim (cost=0.00..2485226.70 rows=15562513 width=26) (actual +time=0.016..2.532 rows=2175 loops=1) + Total runtime: 9.592 ms +(5 rows) + +statgen=> explain analyze select * from subject_source where +source='SCH'; + +QUERY PLAN +------------------------------------------------------------------------------------------------------------------------------------------------------------------------ + Merge Join (cost=0.00..1147.33 rows=1 width=46) (actual +time=0.054..20258.161 rows=1186 loops=1) + Merge Cond: ("outer".id = "inner".target_id) + -> Index Scan using subject_pkey on subject norm (cost=0.00..63.36 +rows=1186 width=28) (actual time=0.022..1.478 rows=1186 loops=1) + -> Index Scan using external_id_map_primary_key on external_id_map +eim (cost=0.00..2524132.99 rows=2335 width=26) (actual +time=0.022..20252.326 rows=1186 loops=1) + Filter: (source = 'SCH'::bpchar) + Total runtime: 20258.922 ms +(6 rows) + +statgen=> \d subject_source + View "public.subject_source" + Column | Type | Modifiers +-----------+-----------------------+----------- + id | bigint | + sex | integer | + parent1 | bigint | + parent2 | bigint | + source | character(3) | + source_id | character varying(32) | +View definition: + SELECT norm.id, norm.sex, norm.parent1, norm.parent2, eim.source, +eim.source_id + FROM subject norm + JOIN util.external_id_map eim ON norm.id = eim.target_id; + +statgen=> \d subject + Table "public.subject" + Column | Type | Modifiers +---------+---------+----------- + id | bigint | not null + sex | integer | + parent1 | bigint | + parent2 | bigint | +Indexes: + "subject_pkey" PRIMARY KEY, btree (id) +Foreign-key constraints: + "subject_parent1" FOREIGN KEY (parent1) REFERENCES subject(id) +DEFERRABLE INITIALLY DEFERRED + "subject_parent2" FOREIGN KEY (parent2) REFERENCES subject(id) +DEFERRABLE INITIALLY DEFERRED + "subject_id_map" FOREIGN KEY (id) REFERENCES +util.external_id_map(target_id) DEFERRABLE INITIALLY DEFERRED + +statgen=> \d util.external_id_map + Table "util.external_id_map" + Column | Type | Modifiers +-----------+-----------------------+----------- + source_id | character varying(32) | not null + source | character(3) | not null + target_id | bigint | not null +Indexes: + "external_id_map_primary_key" PRIMARY KEY, btree (target_id) + "external_id_map_source_source_id_unique" UNIQUE, btree (source, +source_id) + "external_id_map_source" btree (source) + "external_id_map_source_target_id" btree (source, target_id) +Foreign-key constraints: + "external_id_map_source" FOREIGN KEY (source) REFERENCES +util.source(id) + + + +--=-hgMMVV2ifun8oB6Cmlku +Content-Disposition: attachment; filename=pg_settings +Content-Type: text/plain; name=pg_settings; charset=utf-8 +Content-Transfer-Encoding: base64 + +ICAgICAgICAgICAgICBuYW1lICAgICAgICAgICAgICB8ICAgIHNldHRpbmcgICAgIA0KLS0tLS0t +LS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0rLS0tLS0tLS0tLS0tLS0tLQ0KIGFkZF9taXNzaW5n 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SQLgrey- +Received: from mail.metronet.co.uk (mail.metronet.co.uk [213.162.97.75]) + by svr1.postgresql.org (Postfix) with ESMTP id 3445ED6D29 + for ; + Fri, 11 Nov 2005 07:56:58 -0400 (AST) +Received: from mainbox.archonet.com + (84-51-143-99.archon037.adsl.metronet.co.uk [84.51.143.99]) + by smtp.metronet.co.uk (MetroNet Mail) with ESMTP + id CDBD740C4ED; Fri, 11 Nov 2005 11:55:26 +0000 (GMT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by mainbox.archonet.com (Postfix) with ESMTP id DB8A015F97; + Fri, 11 Nov 2005 11:51:58 +0000 (GMT) +Received: from mainbox.archonet.com ([127.0.0.1]) + by localhost (mainbox [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id 09495-02; Fri, 11 Nov 2005 11:51:55 +0000 (GMT) +Received: from [192.168.1.17] (client17.office.archonet.com [192.168.1.17]) + by mainbox.archonet.com (Postfix) with ESMTP id 9AA8015F8F; + Fri, 11 Nov 2005 11:51:55 +0000 (GMT) +Message-ID: <437485DB.50005@archonet.com> +Date: Fri, 11 Nov 2005 11:51:55 +0000 +From: Richard Huxton +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20051013) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Mitch Skinner +Cc: Tom Lane , pgsql-performance@postgresql.org +Subject: Re: same plan, add 1 condition, 1900x slower +References: <1131630176.29496.91.camel@enzian> + <10164.1131643400@sss.pgh.pa.us> + <1131700635.29496.136.camel@enzian> +In-Reply-To: <1131700635.29496.136.camel@enzian> +Content-Type: text/plain; charset=ISO-8859-15; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.031 required=5 tests=[AWL=0.031] +X-Spam-Score: 0.031 +X-Spam-Level: +X-Archive-Number: 200511/204 +X-Sequence-Number: 15461 + +Mitch Skinner wrote: +> +> The version with the condition is definitely doing more I/O. The +> version without the condition doesn't read at all. +[snip] +> relname | relpages | reltuples +> -----------------------------+----------+------------- +> external_id_map | 126883 | 1.55625e+07 +> external_id_map_primary_key | 64607 | 1.55625e+07 +> subject | 31 | 1186 +> subject_pkey | 19 | 1186 + +Does external_id_map really have 15 million rows? If not, try a VACUUM +FULL on it. Be prepared to give it some time to complete. + +-- + Richard Huxton + Archonet Ltd + +From pgsql-performance-owner@postgresql.org Fri Nov 11 10:10:51 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 4000BDAABF + for ; + Fri, 11 Nov 2005 10:10:50 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 62311-02 + for ; + Fri, 11 Nov 2005 14:10:46 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 9E3B4DA481 + for ; + Fri, 11 Nov 2005 10:10:48 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jABE9bpT018037; + Fri, 11 Nov 2005 09:09:37 -0500 (EST) +To: Mitch Skinner +cc: pgsql-performance@postgresql.org +Subject: Re: same plan, add 1 condition, 1900x slower +In-reply-to: <1131700635.29496.136.camel@enzian> +References: <1131630176.29496.91.camel@enzian> + <10164.1131643400@sss.pgh.pa.us> + <1131700635.29496.136.camel@enzian> +Comments: In-reply-to Mitch Skinner + message dated "Fri, 11 Nov 2005 01:17:15 -0800" +Date: Fri, 11 Nov 2005 09:09:36 -0500 +Message-ID: <18036.1131718176@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/205 +X-Sequence-Number: 15462 + +Mitch Skinner writes: +> On Thu, 2005-11-10 at 12:23 -0500, Tom Lane wrote: +>> Apparently, you are using a platform and/or locale in which strcoll() is +>> spectacularly, god-awfully slow --- on the order of 10 msec per comparison. + +> The version with the condition is definitely doing more I/O. The +> version without the condition doesn't read at all. + +That's pretty interesting, but what file(s) is it reading exactly? + +It could still be strcoll's fault. The only plausible explanation +I can think of for strcoll being so slow is if for some reason it were +re-reading the locale definition file every time, instead of setting up +just once. + +If it is hitting Postgres files, it'd be interesting to look at exactly +which files and what the distribution of seek offsets is. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 11 10:18:28 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 67DB2DA423 + for ; + Fri, 11 Nov 2005 10:18:26 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 58096-09 + for ; + Fri, 11 Nov 2005 14:18:22 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 245DED9577 + for ; + Fri, 11 Nov 2005 10:18:23 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jABEH4G8018121; + Fri, 11 Nov 2005 09:17:04 -0500 (EST) +To: Richard Huxton +cc: Mitch Skinner , pgsql-performance@postgresql.org +Subject: Re: same plan, add 1 condition, 1900x slower +In-reply-to: <437485DB.50005@archonet.com> +References: <1131630176.29496.91.camel@enzian> + <10164.1131643400@sss.pgh.pa.us> + <1131700635.29496.136.camel@enzian> <437485DB.50005@archonet.com> +Comments: In-reply-to Richard Huxton + message dated "Fri, 11 Nov 2005 11:51:55 +0000" +Date: Fri, 11 Nov 2005 09:17:04 -0500 +Message-ID: <18120.1131718624@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/206 +X-Sequence-Number: 15463 + +Richard Huxton writes: +> Mitch Skinner wrote: +>> The version with the condition is definitely doing more I/O. The +>> version without the condition doesn't read at all. + +> Does external_id_map really have 15 million rows? If not, try a VACUUM +> FULL on it. Be prepared to give it some time to complete. + +Please don't, actually, until we understand what's going on. + +The thing is that the given plan will fetch every row indicated by the +index in both cases, in order to check the row's visibility. I don't +see how an additional test on a non-indexed column would cause any +additional I/O. If the value were large enough to be toasted +out-of-line then it could cause toast table accesses ... but we're +speaking of a char(3). + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 11 10:20:43 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8A37ED6D19 + for ; + Fri, 11 Nov 2005 10:20:41 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 61826-06 + for ; + Fri, 11 Nov 2005 14:20:36 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail2.egcrc.net (63-193-204-9.egcrc.org [63.193.204.9]) + by svr1.postgresql.org (Postfix) with ESMTP id 6578DD7370 + for ; + Fri, 11 Nov 2005 10:20:37 -0400 (AST) +Received: from egcrc-ex01.egcrc.org ([172.16.1.4]) by mail2.egcrc.net with + Microsoft SMTPSVC(6.0.3790.211); Fri, 11 Nov 2005 06:20:41 -0800 +Received: from 172.16.0.166 ([172.16.0.166]) by egcrc-ex01.egcrc.org + ([172.16.1.4]) with Microsoft Exchange Server HTTP-DAV ; + Fri, 11 Nov 2005 14:20:40 +0000 +Received: from enzian by egcrc-ex01.egcrc.org; 11 Nov 2005 06:20:43 -0800 +Subject: Re: same plan, add 1 condition, 1900x slower +From: Mitch Skinner +To: Richard Huxton +Cc: Tom Lane , pgsql-performance@postgresql.org +In-Reply-To: <437485DB.50005@archonet.com> +References: <1131630176.29496.91.camel@enzian> + <10164.1131643400@sss.pgh.pa.us> <1131700635.29496.136.camel@enzian> + <437485DB.50005@archonet.com> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Fri, 11 Nov 2005 06:20:43 -0800 +Message-Id: <1131718843.29496.197.camel@enzian> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) +X-OriginalArrivalTime: 11 Nov 2005 14:20:41.0479 (UTC) + FILETIME=[18905970:01C5E6CB] +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/207 +X-Sequence-Number: 15464 + +On Fri, 2005-11-11 at 11:51 +0000, Richard Huxton wrote: +> Does external_id_map really have 15 million rows? If not, try a VACUUM +> FULL on it. Be prepared to give it some time to complete. + +Thanks for the reply. It does indeed have that many rows: +statgen=> select count(*) from util.external_id_map ; + count +---------- + 15562513 +(1 row) + +That table never gets deletions or updates, only insertions and reads. +For fun and base-covering, I'm running a full vacuum now. Usually +there's just a nightly lazy vacuum. + +If it helps, here's some background on what we're doing and why (plus +some stuff at the end about how it relates to Postgres): + +We get very similar data from multiple sources, and I want to be able to +combine it all into one schema. The data from different sources is +similar enough (it's generally constrained by the underlying biology, +e.g., each person has a father and a mother, two versions of each +regular chromosome, etc.) that I think putting it all into one set of +tables makes sense. + +Different people in our group use different tools (Python, R, Java), so +instead of integrating at the code level (like a shared class hierarchy) +we use the schema as our shared idea of the data. This helps make my +analyses comparable to the analyses from my co-workers. We don't all +want to have to write basic sanity checks in each of our languages, so +we want to be able to have foreign keys in the schema. Having foreign +keys and multiple data sources means that we have to generate our own +internal identifiers (otherwise we'd expect to have ID collisions from +different sources). I'd like to be able to have a stable +internal-external ID mapping (this is actually something we spent a lot +of time arguing about), so we have a table that does exactly that. + +When we import data, we do a bunch of joins against the external_id_map +table to translate external IDs into internal IDs. It means that the +external_id_map table gets pretty big and the joins can take a long time +(it takes four hours to import one 11-million row source table into our +canonical schema, because we have to do 5 ID translations per row on +that one), but we don't need to import data too often so it works. The +main speed concern is that exploratory data analyses are pretty +interactive, and also sometimes you want to run a bunch of analyses in +parallel, and if the queries are slow that can be a bottleneck. + +I'm looking forward to partitioning the external_id_map table with 8.1, +and when Greenplum comes out with their stuff we'll probably take a +look. If the main Postgres engine had parallel query execution, I'd be +pretty happy. I also followed the external sort thread with interest, +but I didn't get the impression that there was a very clear consensus +there. + +Since some of our sources change over time, and I can't generally expect +them to have timestamps on their data, what we do when we re-import from +a source is delete everything out of the canonical tables from that +source and then re-insert. It sounds like mass deletions are not such a +common thing to do; I think there was a thread about this recently and +Tom questioned the real-world need to worry about that workload. I was +thinking that maybe the foreign key integrity checks might be better +done by a join rather than a per-deleted-row trigger queue, but since +all my foreign keys are indexed on both ends it doesn't look like a +bottleneck. + +Anyway, all that probably has an effect on the data distribution in our +tables and indexes. I'll report back on the effect of the full vacuum. + +Thanks for reading, +Mitch + +From pgsql-performance-owner@postgresql.org Fri Nov 11 11:24:45 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CD3EDD6D19 + for ; + Fri, 11 Nov 2005 11:24:44 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 86610-03 + for ; + Fri, 11 Nov 2005 15:24:40 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail2.egcrc.net (63-193-204-9.egcrc.org [63.193.204.9]) + by svr1.postgresql.org (Postfix) with ESMTP id DA08FDB381 + for ; + Fri, 11 Nov 2005 11:24:40 -0400 (AST) +Received: from egcrc-ex01.egcrc.org ([172.16.1.4]) by mail2.egcrc.net with + Microsoft SMTPSVC(6.0.3790.211); Fri, 11 Nov 2005 07:24:45 -0800 +Received: from 172.16.0.166 ([172.16.0.166]) by egcrc-ex01.egcrc.org + ([172.16.1.4]) with Microsoft Exchange Server HTTP-DAV ; + Fri, 11 Nov 2005 15:24:45 +0000 +Received: from enzian by egcrc-ex01.egcrc.org; 11 Nov 2005 07:24:48 -0800 +Subject: Re: same plan, add 1 condition, 1900x slower +From: Mitch Skinner +To: Tom Lane +Cc: Richard Huxton , pgsql-performance@postgresql.org +In-Reply-To: <18120.1131718624@sss.pgh.pa.us> +References: <1131630176.29496.91.camel@enzian> + <10164.1131643400@sss.pgh.pa.us> <1131700635.29496.136.camel@enzian> + <437485DB.50005@archonet.com> <18120.1131718624@sss.pgh.pa.us> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Fri, 11 Nov 2005 07:24:41 -0800 +Message-Id: <1131722682.29496.229.camel@enzian> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) +X-OriginalArrivalTime: 11 Nov 2005 15:24:45.0718 (UTC) + FILETIME=[0BE8AB60:01C5E6D4] +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/208 +X-Sequence-Number: 15465 + +On Fri, 2005-11-11 at 09:17 -0500, Tom Lane wrote: +> Richard Huxton writes: +> > Does external_id_map really have 15 million rows? If not, try a VACUUM +> > FULL on it. Be prepared to give it some time to complete. +> +> Please don't, actually, until we understand what's going on. + +Ack, I was the middle of the vacuum full already when I got this. I +still have the strace and lsof output from before the vacuum full. It's +definitely reading Postgres files: + +bash-2.05b$ grep '^read' subsourcestrace | cut -d, -f1 | sort | uniq -c + 100453 read(44 + 48218 read(47 +bash-2.05b$ grep 'seek' subsourcestrace | cut -d, -f1 | sort | uniq -c + 1 _llseek(40 + 1 _llseek(43 + 35421 _llseek(44 + 1 _llseek(45 + 1 _llseek(46 + 39787 _llseek(47 + 1 _llseek(48 + +File handles: +44 - external_id_map +47 - external_id_map_primary_key +40 - subject +43 - subject_pkey +45 - external_id_map_source +46 - external_id_map_source_target_id +48 - external_id_map_source_source_id_unique + +As far as the seek offsets go, R doesn't want to do a histogram for me +without using up more RAM than I have. I put up some files at: +http://arctur.us/pgsql/ +They are: +subsourcestrace - the strace output from "select * from subject_source +where source='SCH'" +subsourcestrace-nocond - the strace output from "select * from +subject_source" +subsourcelsof - the lsof output (for mapping from file handles to file +names) +relfilenode.html - for mapping from file names to table/index names (I +think I've gotten all the relevant file handle-table name mappings +above, though) +seekoff-44 - just the beginning seek offsets for the 44 file handle +(external_id_map) +seekoff-47 - just the beginning seek offsets for the 47 file handle +(external_id_map_primary_key) + +The vacuum full is still going; I'll let you know if it changes things. + +> The thing is that the given plan will fetch every row indicated by the +> index in both cases, in order to check the row's visibility. I don't +> see how an additional test on a non-indexed column would cause any +> additional I/O. If the value were large enough to be toasted +> out-of-line then it could cause toast table accesses ... but we're +> speaking of a char(3). + +Pardon my ignorance, but do the visibility check and the check of the +condition happen at different stages of execution? Would it end up +checking the condition for all 15M rows, but only checking visibility +for the 1200 rows that come back from the join? I guess I'm confused +about what "every row indicated by the index" means in the context of +the join. + +Thanks for taking an interest, +Mitch + + +From pgsql-performance-owner@postgresql.org Fri Nov 11 11:34:48 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id C1D9BDB3D6 + for ; + Fri, 11 Nov 2005 11:34:47 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 90174-05 + for ; + Fri, 11 Nov 2005 15:34:43 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 7A181DB438 + for ; + Fri, 11 Nov 2005 11:34:45 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jABFXUAh018884; + Fri, 11 Nov 2005 10:33:30 -0500 (EST) +To: Mitch Skinner +cc: Richard Huxton , pgsql-performance@postgresql.org +Subject: Re: same plan, add 1 condition, 1900x slower +In-reply-to: <1131722682.29496.229.camel@enzian> +References: <1131630176.29496.91.camel@enzian> + <10164.1131643400@sss.pgh.pa.us> + <1131700635.29496.136.camel@enzian> + <437485DB.50005@archonet.com> <18120.1131718624@sss.pgh.pa.us> + <1131722682.29496.229.camel@enzian> +Comments: In-reply-to Mitch Skinner + message dated "Fri, 11 Nov 2005 07:24:41 -0800" +Date: Fri, 11 Nov 2005 10:33:30 -0500 +Message-ID: <18883.1131723210@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/209 +X-Sequence-Number: 15466 + +Mitch Skinner writes: +> On Fri, 2005-11-11 at 09:17 -0500, Tom Lane wrote: +>> Please don't, actually, until we understand what's going on. + +> Ack, I was the middle of the vacuum full already when I got this. + +Given what you said about no deletions or updates, the vacuum should +have no effect anyway, so don't panic. + +> I put up some files at: http://arctur.us/pgsql/ + +Great, I'll take a look ... + +> Pardon my ignorance, but do the visibility check and the check of the +> condition happen at different stages of execution? Would it end up +> checking the condition for all 15M rows, but only checking visibility +> for the 1200 rows that come back from the join? + +No, the visibility check happens first. The timing does seem consistent +with the idea that the comparison is being done at all 15M rows, but +your other EXPLAIN shows that only 2K rows are actually retrieved, which +presumably is because the merge doesn't need the rest. (Merge will stop +scanning either input when it runs out of rows on the other side; so +this sort of plan is very fast if the range of keys on one side is +smaller than the range on the other. The numbers from the no-comparison +EXPLAIN ANALYZE indicate that that is happening for your case.) So the +comparison should happen for at most 2K rows too. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 11 11:54:33 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 17B8FDB127 + for ; + Fri, 11 Nov 2005 11:54:33 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 99258-02 + for ; + Fri, 11 Nov 2005 15:54:29 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 75C39DA423 + for ; + Fri, 11 Nov 2005 11:54:31 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jABFrEL3019096; + Fri, 11 Nov 2005 10:53:14 -0500 (EST) +To: Mitch Skinner +cc: Richard Huxton , pgsql-performance@postgresql.org +Subject: Re: same plan, add 1 condition, 1900x slower +In-reply-to: <18883.1131723210@sss.pgh.pa.us> +References: <1131630176.29496.91.camel@enzian> + <10164.1131643400@sss.pgh.pa.us> + <1131700635.29496.136.camel@enzian> + <437485DB.50005@archonet.com> <18120.1131718624@sss.pgh.pa.us> + <1131722682.29496.229.camel@enzian> + <18883.1131723210@sss.pgh.pa.us> +Comments: In-reply-to Tom Lane + message dated "Fri, 11 Nov 2005 10:33:30 -0500" +Date: Fri, 11 Nov 2005 10:53:14 -0500 +Message-ID: <19095.1131724394@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/210 +X-Sequence-Number: 15467 + +I wrote: +> No, the visibility check happens first. The timing does seem consistent +> with the idea that the comparison is being done at all 15M rows, but +> your other EXPLAIN shows that only 2K rows are actually retrieved, which +> presumably is because the merge doesn't need the rest. (Merge will stop +> scanning either input when it runs out of rows on the other side; so +> this sort of plan is very fast if the range of keys on one side is +> smaller than the range on the other. The numbers from the no-comparison +> EXPLAIN ANALYZE indicate that that is happening for your case.) So the +> comparison should happen for at most 2K rows too. + +After re-reading your explanation of what you're doing with the data, +I thought of a possible explanation. Is the "source" value exactly +correlated with the external_id_map primary key? What could be +happening is this: + +1. We can see from the EXPLAIN ANALYZE for the no-comparison case that +the merge join stops after fetching only 2175 rows from external_id_map. +This implies that the subject table joins to the first couple thousand +entries in external_id_map and nothing beyond that. In particular, the +merge join must have observed that the join key in the 2175'th row (in +index order) of external_id_map was larger than the last (largest) join +key in subject. + +2. Let's suppose that source = 'SCH' is false for the 2175'th row of +external_id_map and every one after that. Then what will happen is that +the index scan will vainly seek through the entire external_id_map, +looking for a row that its filter allows it to return, not knowing that +the merge join has no use for any of those rows. + +If this is the story, and you need to make this sort of query fast, +then what you need to do is incorporate the "source" value into the +external_id_map index key somehow. Then the index scan would be able to +realize that there is no possibility of finding another row with source += 'SCH'. The simplest way is just to make a 2-column index, but I +wonder whether the source isn't actually redundant with the +external_id_map primary key already ... + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 11 12:56:04 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CF1BFD77DE + for ; + Fri, 11 Nov 2005 12:56:00 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 22147-09 + for ; + Fri, 11 Nov 2005 16:55:56 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail2.egcrc.net (63-193-204-9.egcrc.org [63.193.204.9]) + by svr1.postgresql.org (Postfix) with ESMTP id DEB59D6D88 + for ; + Fri, 11 Nov 2005 12:55:55 -0400 (AST) +Received: from egcrc-ex01.egcrc.org ([172.16.1.4]) by mail2.egcrc.net with + Microsoft SMTPSVC(6.0.3790.211); Fri, 11 Nov 2005 08:55:53 -0800 +Received: from 66.245.216.181 ([66.245.216.181]) by egcrc-ex01.egcrc.org + ([172.16.1.4]) via Exchange Front-End Server mail.egcrc.net + ([172.16.1.9]) with Microsoft Exchange Server HTTP-DAV ; + Fri, 11 Nov 2005 16:55:53 +0000 +Received: from firebolt by mail.egcrc.net; 11 Nov 2005 08:57:35 -0800 +Subject: Re: same plan, add 1 condition, 1900x slower +From: Mitchell Skinner +To: Tom Lane +Cc: Richard Huxton , pgsql-performance@postgresql.org +In-Reply-To: <19095.1131724394@sss.pgh.pa.us> +References: <1131630176.29496.91.camel@enzian> + <10164.1131643400@sss.pgh.pa.us> <1131700635.29496.136.camel@enzian> + <437485DB.50005@archonet.com> <18120.1131718624@sss.pgh.pa.us> + <1131722682.29496.229.camel@enzian> <18883.1131723210@sss.pgh.pa.us> + <19095.1131724394@sss.pgh.pa.us> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Fri, 11 Nov 2005 08:57:35 -0800 +Message-Id: <1131728255.10481.51.camel@firebolt> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) +X-OriginalArrivalTime: 11 Nov 2005 16:55:53.0863 (UTC) + FILETIME=[C72D6170:01C5E6E0] +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[RCVD_NUMERIC_HELO=1.253, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/211 +X-Sequence-Number: 15468 + +On Fri, 2005-11-11 at 10:53 -0500, Tom Lane wrote: +> After re-reading your explanation of what you're doing with the data, +> I thought of a possible explanation. Is the "source" value exactly +> correlated with the external_id_map primary key? + +Sort of. In this case, at the beginning of external_id_map, yes, though +further down the table they're not. For example, if we got new subjects +from 'SCH' at this point, they'd get assigned external_id_map.target_id +(the primary key) values that are totally unrelated to what the current +set are (the values in the external_id_map primary key just come off of +a sequence that we use for everything). + +Right now though, since the 'SCH' data came in a contiguous chunk right +at the beginning and hasn't changed or grown since then, the correlation +is pretty exact, I think. It's true that there are no 'SCH' rows in the +table after the first contiguous set (when I get back to work I'll check +exactly what row that is). It's interesting that there are these +correlations in the the data that didn't exist at all in my mental +model. + +> what you need to do is incorporate the "source" value into the +> external_id_map index key somehow. Then the index scan would be able to +> realize that there is no possibility of finding another row with source +> = 'SCH'. The simplest way is just to make a 2-column index + +I thought that's what I had done with the +external_id_map_source_target_id index: + +statgen=> \d util.external_id_map + Table "util.external_id_map" + Column | Type | Modifiers +-----------+-----------------------+----------- + source_id | character varying(32) | not null + source | character(3) | not null + target_id | bigint | not null +Indexes: + "external_id_map_primary_key" PRIMARY KEY, btree (target_id) + "external_id_map_source_source_id_unique" UNIQUE, btree (source, +source_id) + "external_id_map_source" btree (source) + "external_id_map_source_target_id" btree (source, target_id) +Foreign-key constraints: + "external_id_map_source" FOREIGN KEY (source) REFERENCES +util.source(id) + +So if I understand your suggestion correctly, we're back to the "why +isn't this query using index foo" FAQ. For the external_id_map table, +the statistics target for "source" is 200; the other two columns are at +the default level because I didn't think of them as being very +interesting statistics-wise. I suppose I should probably go ahead and +raise the targets for every column of that table; I expect the planning +time is negligible, and our queries tend to be large data-wise. Beyond +that, I'm not sure how else to encourage the use of that index. If I +changed that index to be (target_id, source) would it make a difference? + +Thanks for your help, +Mitch + +From pgsql-performance-owner@postgresql.org Fri Nov 11 13:17:56 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8A128D9853 + for ; + Fri, 11 Nov 2005 13:17:54 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 51693-05 + for ; + Fri, 11 Nov 2005 17:17:53 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id E8853D8ED9 + for ; + Fri, 11 Nov 2005 13:17:52 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jABHGX8I019852; + Fri, 11 Nov 2005 12:16:33 -0500 (EST) +To: Mitchell Skinner +cc: Richard Huxton , pgsql-performance@postgresql.org +Subject: Re: same plan, add 1 condition, 1900x slower +In-reply-to: <1131728255.10481.51.camel@firebolt> +References: <1131630176.29496.91.camel@enzian> + <10164.1131643400@sss.pgh.pa.us> + <1131700635.29496.136.camel@enzian> + <437485DB.50005@archonet.com> <18120.1131718624@sss.pgh.pa.us> + <1131722682.29496.229.camel@enzian> + <18883.1131723210@sss.pgh.pa.us> <19095.1131724394@sss.pgh.pa.us> + <1131728255.10481.51.camel@firebolt> +Comments: In-reply-to Mitchell Skinner + message dated "Fri, 11 Nov 2005 08:57:35 -0800" +Date: Fri, 11 Nov 2005 12:16:33 -0500 +Message-ID: <19851.1131729393@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/212 +X-Sequence-Number: 15469 + +Mitchell Skinner writes: +> On Fri, 2005-11-11 at 10:53 -0500, Tom Lane wrote: +>> what you need to do is incorporate the "source" value into the +>> external_id_map index key somehow. Then the index scan would be able to +>> realize that there is no possibility of finding another row with source +>> = 'SCH'. The simplest way is just to make a 2-column index + +> I thought that's what I had done with the +> external_id_map_source_target_id index: +> "external_id_map_source_target_id" btree (source, target_id) + +> If I changed that index to be (target_id, source) would it make a difference? + +[ fools around with a test case ... ] Seems like not :-(. PG is not +bright enough to realize that an index on (source, target_id) can be +used with a mergejoin on target_id, because the index sort order isn't +compatible. (Given the equality constraint on source, there is an +effective compatibility. I had thought that 8.1 might be able to +detect this, but it seems not to in a simple test case --- there may be +a bug involved there. In any case 8.0 definitely won't see it.) An +index on (target_id, source) would be recognized as mergejoinable, but +that doesn't solve the problem because an index condition on the second +column doesn't provide enough information to know that the scan can stop +early. + +Given your comment that the correlation is accidental, it may be that +there's not too much point in worrying. The planner is picking this +plan only because it notices the asymmetry in key ranges, and as soon +as some more rows get added with higher-numbered target_ids it will +shift to something else (probably a hash join). + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 11 15:21:40 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 182A2D9853 + for ; + Fri, 11 Nov 2005 15:21:39 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 04515-03 + for ; + Fri, 11 Nov 2005 19:21:08 +0000 (GMT) +X-Greylist: delayed 00:05:01.717908 by SQLgrey- +Received: from mtiwmhc13.worldnet.att.net (mtiwmhc13.worldnet.att.net + [204.127.131.117]) + by svr1.postgresql.org (Postfix) with ESMTP id 15A1FD91B1 + for ; + Fri, 11 Nov 2005 15:21:02 -0400 (AST) +Received: from [10.10.100.50] (unknown[216.113.237.29]) + by worldnet.att.net (mtiwmhc13) with ESMTP + id <2005111119160011300sjt3ie>; Fri, 11 Nov 2005 19:16:00 +0000 +Message-ID: <4374EDF1.5010709@att.net> +Date: Fri, 11 Nov 2005 14:16:01 -0500 +From: DW +Reply-To: dwinner-lists@att.net +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: slow queries after ANALYZE +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.062 required=5 tests=[AWL=0.062] +X-Spam-Score: 0.062 +X-Spam-Level: +X-Archive-Number: 200511/213 +X-Sequence-Number: 15470 + +Hello, + +I'm perplexed. I'm trying to find out why some queries are taking a long +time, and have found that after running analyze, one particular query +becomes slow. + +This query is based on a view that is based on multiple left outer joins +to merge data from lots of tables. + +If I drop the database and reload it from a dump, the query result is +instaneous (less than one second). + +But after I run analyze, it then takes much longer to run -- about 10 +seconds, give or take a few depending on the hardware I'm testing it on. +Earlier today, it was taking almost 30 seconds on the actual production +server -- I restarted pgsql server and the time got knocked down to +about 10 seconds -- another thing I don't understand. + +I've run the query a number of times before and after running analyze, +and the problem reproduces everytime. I also ran with "explain", and saw +that the costs go up dramatically after I run analyze. + +I'm fairly new to postgresql and not very experienced as a db admin to +begin with, but it looks like I'm going to have to get smarter about +this stuff fast, unless it's something the programmers need to deal with +when constructing their code and queries or designing the databases. + +I've already learned that I've commited the cardinal sin of configuring +my new database server with RAID 5 instead of something more sensible +for databases like 0+1, but I've been testing out and replicating this +problem on different hardware, so I know that this issue is not the +direct cause of this. + +Thanks for any info. I can supply more info (like config files, schemas, +etc.) if you think it might help. But I though I would just describe the +problem for starters. + +-DW + + +From pgsql-performance-owner@postgresql.org Fri Nov 11 15:32:16 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D1E04D96AD + for ; + Fri, 11 Nov 2005 15:32:11 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 11333-03 + for ; + Fri, 11 Nov 2005 19:32:09 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 1BEB6D6D1D + for ; + Fri, 11 Nov 2005 15:32:09 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jABJWAM3021007; + Fri, 11 Nov 2005 14:32:10 -0500 (EST) +To: dwinner-lists@att.net +cc: pgsql-performance@postgresql.org +Subject: Re: slow queries after ANALYZE +In-reply-to: <4374EDF1.5010709@att.net> +References: <4374EDF1.5010709@att.net> +Comments: In-reply-to DW + message dated "Fri, 11 Nov 2005 14:16:01 -0500" +Date: Fri, 11 Nov 2005 14:32:10 -0500 +Message-ID: <21006.1131737530@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/214 +X-Sequence-Number: 15471 + +DW writes: +> I'm perplexed. I'm trying to find out why some queries are taking a long +> time, and have found that after running analyze, one particular query +> becomes slow. + +This implies that the planner's default choice of plan (without any +statistics) is better than its choice when informed by statistics. +This is undesirable but not unheard of :-( + +It would be interesting to see EXPLAIN ANALYZE results in both cases, +plus the contents of the relevant pg_stats rows. (BTW, you need not +dump and reload to get back to the virgin state --- just delete the +relevant rows from pg_statistic.) Also we'd want to know exactly what +PG version this is, and on what sort of platform. + +You might be able to fix things by increasing the statistics targets or +tweaking planner cost parameters, but it'd be best to investigate before +trying to fix. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 11 16:48:20 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 708E5DA206 + for ; + Fri, 11 Nov 2005 16:48:18 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 44287-08 + for ; + Fri, 11 Nov 2005 20:48:16 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mtiwmhc12.worldnet.att.net (mtiwmhc12.worldnet.att.net + [204.127.131.116]) + by svr1.postgresql.org (Postfix) with ESMTP id 09315DA049 + for ; + Fri, 11 Nov 2005 16:48:16 -0400 (AST) +Received: from [10.10.100.50] (unknown[216.113.237.29]) + by worldnet.att.net (mtiwmhc12) with ESMTP + id <2005111120481511200f4vq8e>; Fri, 11 Nov 2005 20:48:16 +0000 +Message-ID: <43750390.3090707@att.net> +Date: Fri, 11 Nov 2005 15:48:16 -0500 +From: DW +Reply-To: dwinner-lists@att.net +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: slow queries after ANALYZE +References: <4374EDF1.5010709@att.net> <21006.1131737530@sss.pgh.pa.us> +In-Reply-To: <21006.1131737530@sss.pgh.pa.us> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.047 required=5 tests=[AWL=0.047] +X-Spam-Score: 0.047 +X-Spam-Level: +X-Archive-Number: 200511/215 +X-Sequence-Number: 15472 + +Tom Lane wrote: + +> It would be interesting to see EXPLAIN ANALYZE results in both cases, +> plus the contents of the relevant pg_stats rows. (BTW, you need not +> dump and reload to get back to the virgin state --- just delete the +> relevant rows from pg_statistic.) Also we'd want to know exactly what +> PG version this is, and on what sort of platform. +> + +Thanks for replying. I've got a message into to my team asking if I need +to de-identify some of the table names before I go submitting output to +a public mailing list. + +In the meantime, again I'm new to this -- I got pg_stats; which rows are + the relevent ones? + +Also, I am running postgresql-server-7.4.9 from FreeBSD port (with +optimized CFLAGS turned on during compiling) + +OS: FreeBSD 5.4 p8 + +Thanks, +DW + + +From pgsql-performance-owner@postgresql.org Fri Nov 11 17:25:55 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9E55CD9CF0 + for ; + Fri, 11 Nov 2005 17:25:52 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 63379-03 + for ; + Fri, 11 Nov 2005 21:25:50 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 2021DD9CEC + for ; + Fri, 11 Nov 2005 17:25:50 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jABLPqrb021670; + Fri, 11 Nov 2005 16:25:52 -0500 (EST) +To: dwinner-lists@att.net +cc: pgsql-performance@postgresql.org +Subject: Re: slow queries after ANALYZE +In-reply-to: <43750390.3090707@att.net> +References: <4374EDF1.5010709@att.net> <21006.1131737530@sss.pgh.pa.us> + <43750390.3090707@att.net> +Comments: In-reply-to DW + message dated "Fri, 11 Nov 2005 15:48:16 -0500" +Date: Fri, 11 Nov 2005 16:25:52 -0500 +Message-ID: <21669.1131744352@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/216 +X-Sequence-Number: 15473 + +DW writes: +> In the meantime, again I'm new to this -- I got pg_stats; which rows are +> the relevent ones? + +The ones for columns that are mentioned in the problem query. +I don't think you need to worry about columns used only in the SELECT +output list, but anything used in WHERE, GROUP BY, etc is interesting. + +> Also, I am running postgresql-server-7.4.9 from FreeBSD port (with +> optimized CFLAGS turned on during compiling) +> OS: FreeBSD 5.4 p8 + +The hardware environment (particularly disks/filesystems) is relevant +too. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 11 18:48:29 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6D179D8FD3 + for ; + Fri, 11 Nov 2005 18:48:28 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 97991-09 + for ; + Fri, 11 Nov 2005 22:48:22 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from tbmail.tradebot.com + (Tradebot-Systems-1096753.cust-rtr.swbell.net [68.90.170.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 72598D9E4D + for ; + Fri, 11 Nov 2005 18:48:23 -0400 (AST) +Received: from 192.168.200.29 ([192.168.200.29]) by tbmail.tradebot.com + ([192.168.1.50]) with Microsoft Exchange Server HTTP-DAV ; + Fri, 11 Nov 2005 22:48:25 +0000 +Received: from krb06 by TBMAIL; 11 Nov 2005 16:48:25 -0600 +Subject: Re: 8.x index insert performance +From: Kelly Burkhart +To: Tom Lane +Cc: pgsql-performance@postgresql.org +In-Reply-To: <13167.1131668008@sss.pgh.pa.us> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD725@Herge.rcsinc.local> + <20051031193547.GA3311@mark.mielke.cc> <18647.1130790629@sss.pgh.pa.us> + <1130792391.7026.55.camel@krb06.tradebot.com> + <19065.1130793527@sss.pgh.pa.us> + <1130852029.7026.88.camel@krb06.tradebot.com> + <24845.1130852730@sss.pgh.pa.us> + <1131660117.7514.57.camel@krb06.tradebot.com> + <13167.1131668008@sss.pgh.pa.us> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Fri, 11 Nov 2005 16:48:25 -0600 +Message-Id: <1131749305.14024.32.camel@krb06.tradebot.com> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.1 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.017 required=5 tests=[AWL=0.016, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.017 +X-Spam-Level: +X-Archive-Number: 200511/217 +X-Sequence-Number: 15474 + +On Thu, 2005-11-10 at 19:13 -0500, Tom Lane wrote: +> Kelly Burkhart writes: +> > ... A graph showing the performance +> > characteristics is here: +> +> > +> +> I hadn't looked at this chart till just now, but it sure seems to put a +> crimp in my theory that you are running out of room to hold the indexes +> in RAM. That theory would predict that once you fall over the knee of +> the curve, performance would get steadily worse; instead it gets +> markedly worse and then improves a bit. And there's another cycle of +> worse-and-better around 80M rows. I have *no* idea what's up with that. +> Anyone? Kelly, could there be any patterns in the data that might be +> related? + +I modified my original program to insert generated, sequential data. +The following graph shows the results to be flat: + + + +Thus, hardware is sufficient to handle predictably sequential data. +There very well could be a pattern in the data which could affect +things, however, I'm not sure how to identify it in 100K rows out of +100M. + +If I could identify a pattern, what could I do about it? Could I do +some kind of a reversible transform on the data? Is it better to insert +nearly random values? Or nearly sequential? + + +I now have an 8G and a 16G machine I'm loading the data into. I'll +report back after that's done. + +I also want to try eliminating the order_main table, moving fields to +the transition table. This will reduce the number of index updates +significantly at the cost of some wasted space in the table... + +-K + +From pgsql-performance-owner@postgresql.org Fri Nov 11 18:58:37 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 72191D9D44 + for ; + Fri, 11 Nov 2005 18:58:34 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 05141-05 + for ; + Fri, 11 Nov 2005 22:58:29 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from gwmta.wicourts.gov (gwmta.wicourts.gov [165.219.244.99]) + by svr1.postgresql.org (Postfix) with ESMTP id D19E7D9CD5 + for ; + Fri, 11 Nov 2005 18:58:30 -0400 (AST) +Received: from Courts-MTA by gwmta.wicourts.gov + with Novell_GroupWise; Fri, 11 Nov 2005 16:58:28 -0600 +Message-Id: <4374CDA90200002500000651@gwmta.wicourts.gov> +X-Mailer: Novell GroupWise Internet Agent 7.0 +Date: Fri, 11 Nov 2005 16:58:17 -0600 +From: "Kevin Grittner" +To: , +Cc: +Subject: Re: 8.x index insert performance +Mime-Version: 1.0 +Content-Type: text/plain; charset=US-ASCII +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.002 required=5 tests=[AWL=0.002] +X-Spam-Score: 0.002 +X-Spam-Level: +X-Archive-Number: 200511/218 +X-Sequence-Number: 15475 + +That sure seems to bolster the theory that performance is degrading +because you exhaust the cache space and need to start reading +index pages. When inserting sequential data, you don't need to +randomly access pages all over the index tree. + +-Kevin + + +>>> Kelly Burkhart >>> + +I modified my original program to insert generated, sequential data. +The following graph shows the results to be flat: + + + + +From pgsql-performance-owner@postgresql.org Fri Nov 11 19:02:12 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 738F7D9A6C + for ; + Fri, 11 Nov 2005 19:02:11 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 07080-03 + for ; + Fri, 11 Nov 2005 23:02:08 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id F2C2ED96AD + for ; + Fri, 11 Nov 2005 19:02:09 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jABN2CDv022259; + Fri, 11 Nov 2005 18:02:12 -0500 (EST) +To: Kelly Burkhart +cc: pgsql-performance@postgresql.org +Subject: Re: 8.x index insert performance +In-reply-to: <1131749305.14024.32.camel@krb06.tradebot.com> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD725@Herge.rcsinc.local> + <20051031193547.GA3311@mark.mielke.cc> + <18647.1130790629@sss.pgh.pa.us> + <1130792391.7026.55.camel@krb06.tradebot.com> + <19065.1130793527@sss.pgh.pa.us> + <1130852029.7026.88.camel@krb06.tradebot.com> + <24845.1130852730@sss.pgh.pa.us> + <1131660117.7514.57.camel@krb06.tradebot.com> + <13167.1131668008@sss.pgh.pa.us> + <1131749305.14024.32.camel@krb06.tradebot.com> +Comments: In-reply-to Kelly Burkhart + message dated "Fri, 11 Nov 2005 16:48:25 -0600" +Date: Fri, 11 Nov 2005 18:02:11 -0500 +Message-ID: <22258.1131750131@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/219 +X-Sequence-Number: 15476 + +Kelly Burkhart writes: +> On Thu, 2005-11-10 at 19:13 -0500, Tom Lane wrote: +>> Kelly, could there be any patterns in the data that might be +>> related? + +> I modified my original program to insert generated, sequential data. +> The following graph shows the results to be flat: +> +> Thus, hardware is sufficient to handle predictably sequential data. + +Yeah, inserting sequentially increasing data would only ever touch the +right-hand edge of the btree, so memory requirements would be pretty low +and constant. + +> There very well could be a pattern in the data which could affect +> things, however, I'm not sure how to identify it in 100K rows out of +> 100M. + +I conjecture that the problem areas represent places where the key +sequence is significantly "more random" than it is elsewhere. Hard +to be more specific than that though. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Sat Nov 12 05:14:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id F3D66DB49E + for ; + Sat, 12 Nov 2005 05:14:48 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 01048-10 + for ; + Sat, 12 Nov 2005 09:14:46 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.200]) + by svr1.postgresql.org (Postfix) with ESMTP id 182B3DB49B + for ; + Sat, 12 Nov 2005 05:14:46 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id 57so706214wri + for ; + Sat, 12 Nov 2005 01:14:49 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:references; + b=AbIJJQoCaTN9OwP99n3Eem5kNWrUaQOi6yq2DeL1PsYqYsEL5Wh7Z275638RkdZtnGnzj+2ulQZDeSySjsb6jSstCDpEwg65W+qm5JmNy9Sg0Vad7LneoJs8tqzhogRgB4ByNRKtIE+dNL2u2ZaDf0Sh9bIyYT+0j/2mgWHO72Y= +Received: by 10.54.76.9 with SMTP id y9mr1788797wra; + Sat, 12 Nov 2005 01:14:49 -0800 (PST) +Received: by 10.54.117.8 with HTTP; Sat, 12 Nov 2005 01:14:49 -0800 (PST) +Message-ID: <9e4684ce0511120114m32254efen2faa6563146db202@mail.gmail.com> +Date: Sat, 12 Nov 2005 10:14:49 +0100 +From: hubert depesz lubaczewski +To: dwinner-lists@att.net +Subject: Re: slow queries after ANALYZE +Cc: pgsql-performance@postgresql.org +In-Reply-To: <4374EDF1.5010709@att.net> +MIME-Version: 1.0 +Content-Type: multipart/alternative; + boundary="----=_Part_2159_29838048.1131786889103" +References: <4374EDF1.5010709@att.net> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.052 required=5 tests=[AWL=0.051, + HTML_MESSAGE=0.001] +X-Spam-Score: 0.052 +X-Spam-Level: +X-Archive-Number: 200511/220 +X-Sequence-Number: 15477 + +------=_Part_2159_29838048.1131786889103 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline + +On 11/11/05, DW wrote: +> +> I'm perplexed. I'm trying to find out why some queries are taking a long +> time, and have found that after running analyze, one particular query +> becomes slow. +> + +i have had exactly the same problem very recently. +what helped? increasing statistics on come column. +which ones? +make: +explain analyze ; +and check in which situations you gget the biggest change of "estiamted +rows" and "actual rows". +then check what this particular part of your statement is touching, and +increase appropriate statistics. + +depesz + +------=_Part_2159_29838048.1131786889103 +Content-Type: text/html; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline + +On 11/11/05, DW <dwinner-lists@att.net> wrote:
+I'm perplexed. I'm trying to find out why some queries are taking a longtime, and have found that after running analyze,  one particular= + query
becomes slow.

+i have had exactly the same problem very recently.
+what helped? increasing statistics on come column.
+which ones?
+make:
+explain analyze <your select>;
+and check in which situations you gget the biggest change of "estiamte= +d rows" and "actual rows".
+then check what this particular part of your statement is touching, and inc= +rease appropriate statistics.
+
+depesz
+ +------=_Part_2159_29838048.1131786889103-- + +From pgsql-performance-owner@postgresql.org Sat Nov 12 10:18:11 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8479ED936B + for ; + Sat, 12 Nov 2005 10:18:10 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 23818-02 + for ; + Sat, 12 Nov 2005 14:18:06 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from hoboe1bl1.telenet-ops.be (hoboe1bl1.telenet-ops.be + [195.130.137.72]) + by svr1.postgresql.org (Postfix) with ESMTP id C9E0AD682F + for ; + Sat, 12 Nov 2005 10:18:07 -0400 (AST) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by hoboe1bl1.telenet-ops.be (Postfix) with SMTP + id 0497D38071; Sat, 12 Nov 2005 15:18:11 +0100 (CET) +Received: from [10.0.1.2] (d5152B313.access.telenet.be [81.82.179.19]) + by hoboe1bl1.telenet-ops.be (Postfix) with ESMTP + id 645C53818D; Sat, 12 Nov 2005 15:18:10 +0100 (CET) +Mime-Version: 1.0 (Apple Message framework v623) +To: pgsql-performance@postgresql.org +Message-Id: +Content-Type: multipart/mixed; boundary=Apple-Mail-206-1026550905 +Cc: Hendrik De Hertogh +Subject: IO Error +From: Yves Vindevogel +Date: Sat, 12 Nov 2005 15:18:09 +0100 +X-Mailer: Apple Mail (2.623) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/221 +X-Sequence-Number: 15478 + + +--Apple-Mail-206-1026550905 +Content-Type: multipart/alternative; + boundary=Apple-Mail-207-1026550905 + + +--Apple-Mail-207-1026550905 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/plain; + charset=ISO-8859-1; + format=flowed + +ns30966:~# NOTICE: Executing SQL: update tblPrintjobs set=20 +ApplicationType =3D 1 where ApplicationType is null and=20 +upper(DocumentName) like '%.DOC' + +ns30966:~# NOTICE: Executing SQL: update tblPrintjobs set=20 +ApplicationType =3D 1 where ApplicationType is null and=20 +upper(DocumentName) like 'DOCUMENT%' + +ns30966:~# +ns30966:~# ERROR: could not read block 3231 of relation=20 +1663/165707259/173511769: Input/output error +CONTEXT: SQL statement "update tblPrintjobs set ApplicationType =3D 1=20= + +where ApplicationType is null and upper(DocumentName) like=20 +'DOCUMENT%'" +PL/pgSQL function "fnapplicationtype" line 30 at execute statement + +[1]+ Exit 1 psql -d kpmg -c "select=20 +fnApplicationType()" + + +I get this error. Is this hardware related or could it be something=20 +with the postgresql.conf settings. +I changed them for performance reasons. (More memory, more wal=20 +buffers). +There are 2 databases. One got the error yesterday, I dropped it (was=20= + +brand new), recreated it and the error was gone. +Now the error is there again on another database. + +Personally, I think it's a HD error. + +Met vriendelijke groeten, +Bien =E0 vous, +Kind regards, + +Yves Vindevogel +Implements + + +--Apple-Mail-207-1026550905 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/enriched; + charset=ISO-8859-1 + +ns30966:~# NOTICE: Executing SQL: update tblPrintjobs set +ApplicationType =3D 1 where ApplicationType is null and +upper(DocumentName) like '%.DOC' + + +ns30966:~# NOTICE: Executing SQL: update tblPrintjobs set +ApplicationType =3D 1 where ApplicationType is null and +upper(DocumentName) like 'DOCUMENT%' + + +ns30966:~# + +ns30966:~# ERROR: could not read block 3231 of relation +1663/165707259/173511769: Input/output error + +CONTEXT: SQL statement "update tblPrintjobs set ApplicationType =3D 1 +where ApplicationType is null and upper(DocumentName) like +'DOCUMENT%'" + +PL/pgSQL function "fnapplicationtype" line 30 at execute statement + + +[1]+ Exit 1 psql -d kpmg -c "select +fnApplicationType()" + + + +I get this error. Is this hardware related or could it be something +with the postgresql.conf settings. + +I changed them for performance reasons. (More memory, more wal +buffers). + +There are 2 databases. One got the error yesterday, I dropped it (was +brand new), recreated it and the error was gone. + +Now the error is there again on another database. + + +Personally, I think it's a HD error. + + +Met vriendelijke groeten, + +Bien =E0 vous, + +Kind regards, + + +Yves Vindevogel + +Implements + + + += + +--Apple-Mail-207-1026550905-- + +--Apple-Mail-206-1026550905 +Content-Transfer-Encoding: base64 +Content-Type: image/tiff; + x-unix-mode=0666; + name="Pasted Graphic 2.tiff" +Content-Disposition: inline; + filename="Pasted Graphic 2.tiff" + +TU0AKgAAFciAP6BP5/wWDQeEQmFQuGQ2HQ+FP5+v9rOh5P9IMBuP8zK9tP8fJNlP8QoNjP8FndhP +8MnyVjJHSMrqFnv9BL1vP9ett2v98PuJxChUOiUWGQOCUalUujOV4PZ/qBluR/mdVtJ/jVHst/ho +9MF/g08WABHJfv8AWa0WoAHFfWuzgg6sB/hY9ysUohjv8qqVqv9LMZxv9ouV40zEYmHUjFY2HPx+ +RNtOl4Rhftt/phiRs6LC/iA5LewnJeWg46W22+02cAHOwa26bC0HPY7TZ7G2G9dv8EHFdP8Om9YP +8rKJov9UtFzv9Dzh/sRvu5/vZ9PzHdeF4zsUqgQRlOR5v9DMBwv8uqe/jZIVwNHu6B0/WAKHvWGr 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+Content-Type: multipart/alternative; + boundary=Apple-Mail-208-1026550907 + + +--Apple-Mail-208-1026550907 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; + charset=US-ASCII; + format=flowed + + + +Mail: yves.vindevogel@implements.be - Mobile: +32 (478) 80 82 91 + +Kempische Steenweg 206 - 3500 Hasselt - Tel-Fax: +32 (11) 43 55 76 + +Web: http://www.implements.be + +First they ignore you. Then they laugh at you. Then they fight you. +Then you win. +Mahatma Ghandi. +--Apple-Mail-208-1026550907 +Content-Transfer-Encoding: 7bit +Content-Type: text/enriched; + charset=US-ASCII + + + + +Mail: yves.vindevogel@implements.be - Mobile: +32 (478) 80 82 91 + + +Kempische Steenweg 206 - 3500 Hasselt - Tel-Fax: +32 (11) 43 55 76 + + +Web: http://www.implements.be + + + +First they ignore you. Then they laugh at you. Then they fight you. +Then you win. + +Mahatma Ghandi. +--Apple-Mail-208-1026550907-- + +--Apple-Mail-206-1026550905-- + + +From pgsql-performance-owner@postgresql.org Sat Nov 12 11:53:16 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9227EDB4F3 + for ; + Sat, 12 Nov 2005 11:53:15 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 96420-08 + for ; + Sat, 12 Nov 2005 15:53:11 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 38323DB4EE + for ; + Sat, 12 Nov 2005 11:53:13 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jACFrE9q027807; + Sat, 12 Nov 2005 10:53:14 -0500 (EST) +To: Yves Vindevogel +cc: pgsql-performance@postgresql.org, + Hendrik De Hertogh +Subject: Re: IO Error +In-reply-to: +References: +Comments: In-reply-to Yves Vindevogel + message dated "Sat, 12 Nov 2005 15:18:09 +0100" +Date: Sat, 12 Nov 2005 10:53:14 -0500 +Message-ID: <27806.1131810794@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/222 +X-Sequence-Number: 15479 + +Yves Vindevogel writes: +> ns30966:~# ERROR: could not read block 3231 of relation +> 1663/165707259/173511769: Input/output error + +> I get this error. Is this hardware related or could it be something +> with the postgresql.conf settings. + +It's a hardware failure --- bad disk block, likely. You might find more +details in the kernel log (/var/log/messages or equivalent). + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 18 16:43:36 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9A979DB873 + for ; + Mon, 14 Nov 2005 15:37:56 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 03386-03 + for ; + Mon, 14 Nov 2005 19:37:52 +0000 (GMT) +Received: from hub.org (hub.org [200.46.204.220]) + by svr1.postgresql.org (Postfix) with ESMTP id 5222DDB86F + for ; + Mon, 14 Nov 2005 15:37:53 -0400 (AST) +Received: from localhost (unknown [200.46.204.144]) + by hub.org (Postfix) with ESMTP id 686F7C08C01 + for ; + Mon, 14 Nov 2005 23:42:14 -0400 (AST) +Received: from hub.org ([200.46.204.220]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 05239-02 for ; + Mon, 14 Nov 2005 19:37:51 +0000 (GMT) +Received: from ganymede.hub.org (blk-222-82-85.eastlink.ca [24.222.82.85]) + by hub.org (Postfix) with ESMTP id 80D2FC08BEC + for ; + Mon, 14 Nov 2005 23:42:12 -0400 (AST) +Received: by ganymede.hub.org (Postfix, from userid 1000) + id 520F94A91B; Mon, 14 Nov 2005 15:37:31 -0400 (AST) +Received: from localhost (localhost [127.0.0.1]) + by ganymede.hub.org (Postfix) with ESMTP id 4DE7D4A88F + for ; + Mon, 14 Nov 2005 15:37:31 -0400 (AST) +X-Return-Path: +X-Received: from ganymede.hub.org ([unix socket]) + by ganymede.hub.org (Cyrus v2.2.12) with LMTPA; + Mon, 14 Nov 2005 09:55:37 -0400 +X-Sieve: CMU Sieve 2.2 +X-Received: from localhost (localhost [127.0.0.1]) + by ganymede.hub.org (Postfix) with ESMTP id 8175B5C1F9 + for ; Mon, 14 Nov 2005 09:55:37 -0400 (AST) +X-Received: from mail.postgresql.org [200.46.204.71] + by localhost with IMAP (fetchmail-6.2.5.2) + for scrappy@localhost (single-drop); + Mon, 14 Nov 2005 09:55:37 -0400 (AST) +X-Received: from svr1.postgresql.org ([unix socket]) + by svr1.postgresql.org (Cyrus v2.2.12) with LMTPA; + Mon, 14 Nov 2005 09:53:52 -0400 +X-Sieve: CMU Sieve 2.2 +X-Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B643CD6D16 + for ; Mon, 14 Nov 2005 09:53:52 -0400 (AST) +X-Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 63542-09 for ; + Mon, 14 Nov 2005 13:53:49 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id EBDEFDB74E + for ; + Mon, 14 Nov 2005 09:25:46 -0400 (AST) +X-Received: from mailserver.sandvine.com (sandvine.com [199.243.201.138]) + by svr2.postgresql.org (Postfix) with ESMTP id 8B3C1F0C06 + for ; + Mon, 14 Nov 2005 13:25:50 +0000 (GMT) +X-MimeOLE: Produced By Microsoft Exchange V6.0.6603.0 +content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: multipart/alternative; + boundary="----_=_NextPart_001_01C5E91E.D67CC41E" +Subject: sort/limit across union all +Date: Mon, 14 Nov 2005 08:25:10 -0500 +Message-ID: <2BCEB9A37A4D354AA276774EE13FB8C263B0F4@mailserver.sandvine.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: sort/limit across union all +Thread-Index: AcXpHuwjr78TzCkNQSSpBxjChIGO1w== +From: "Marc Morin" +To: +X-Virus-Scanned: by amavisd-new at hub.org +ReSent-Date: Mon, 14 Nov 2005 15:37:27 -0400 (AST) +ReSent-From: "Marc G. Fournier" +ReSent-To: pgsql-performance@postgresql.org +ReSent-Subject: sort/limit across union all +ReSent-Message-ID: <20051114153727.M1019@ganymede.hub.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.851 required=5 tests=[AWL=1.851, + HTML_MESSAGE=0.001, UPPERCASE_25_50=0] +X-Spam-Score: 1.851 +X-Spam-Level: * +X-Archive-Number: 200511/381 +X-Sequence-Number: 15638 + +This is a multi-part message in MIME format. + +------_=_NextPart_001_01C5E91E.D67CC41E +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable + +We have a large DB with partitioned tables in postgres. We have had +trouble with a ORDER/LIMIT type query. The order and limit are not +pushed down to the sub-tables.... +=20 +CREATE TABLE base ( + foo int=20 +); +=20 +CREATE TABLE bar_0 + extra int +) INHERITS (base); +ALTER TABLE bar ADD PRIMARY KEY (foo); +=20 +-- repeated for bar_0... bar_40 +=20 +SELECT foo FROM base ORDER BY foo LIMIT 10; +=20 +is real slow. What is required to make the query planner generate the +following instead... (code change i know, but how hard would it be?) +=20 +SELECT + foo +FROM +( + SELECT + * + FROM bar_0 + ORDER BY foo LIMIT 10 +UNION ALL + SELECT + * + FROM bar_1 + ORDER BY foo LIMIT 10 +.... +) AS base +ORDER BY foo +LIMIT 10; +=20 +=20 + +------_=_NextPart_001_01C5E91E.D67CC41E +Content-Type: text/html; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable + + + + + + +
We = +have a large DB=20 +with partitioned tables in postgres.   We have had trouble = +with a=20 +ORDER/LIMIT type query.  The order and limit are not pushed down to = +the=20 +sub-tables....
+
 
+
CREATE = +TABLE base=20 +(
+
    foo int
+
);
+
 
+
CREATE = +TABLE=20 +bar_0
+
    extra int
+
) = +INHERITS=20 +(base);
+
ALTER = +TABLE bar ADD=20 +PRIMARY KEY (foo);
+
 
+
-- = +repeated for=20 +bar_0... bar_40
+
 
+
SELECT = +foo FROM base=20 +ORDER BY foo LIMIT 10;
+
 
+
is = +real slow. What=20 +is required to make the query planner generate the following instead... = +(code=20 +change i know, but how hard would it be?)
+
 
+
SELECT
+
    foo
+
FROM
+
(
+
   =20 +SELECT
+
       =20 +*
+
    FROM = +bar_0
+
    ORDER BY foo = +LIMIT=20 +10
+
UNION ALL
+
    = +SELECT
+
       =20 +*
+
    FROM = +bar_1
+
    ORDER BY foo = +LIMIT=20 +10
+
....
+
) AS base
+
ORDER BY foo
+
LIMIT 10;
+
 
+
 
+ +------_=_NextPart_001_01C5E91E.D67CC41E-- + +From pgsql-performance-owner@postgresql.org Mon Nov 14 10:43:29 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 05FA2DB72A + for ; + Mon, 14 Nov 2005 10:43:28 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 20084-05 + for ; + Mon, 14 Nov 2005 14:43:24 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from tbmail.tradebot.com + (Tradebot-Systems-1096753.cust-rtr.swbell.net [68.90.170.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 5AB4DDB73F + for ; + Mon, 14 Nov 2005 10:43:25 -0400 (AST) +Received: from 192.168.200.29 ([192.168.200.29]) by tbmail.tradebot.com + ([192.168.1.50]) with Microsoft Exchange Server HTTP-DAV ; + Mon, 14 Nov 2005 14:43:30 +0000 +Received: from krb06 by TBMAIL; 14 Nov 2005 08:43:30 -0600 +Subject: Re: 8.x index insert performance +From: Kelly Burkhart +To: Tom Lane +Cc: pgsql-performance@postgresql.org +In-Reply-To: <22258.1131750131@sss.pgh.pa.us> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD725@Herge.rcsinc.local> + <20051031193547.GA3311@mark.mielke.cc> <18647.1130790629@sss.pgh.pa.us> + <1130792391.7026.55.camel@krb06.tradebot.com> + <19065.1130793527@sss.pgh.pa.us> + <1130852029.7026.88.camel@krb06.tradebot.com> + <24845.1130852730@sss.pgh.pa.us> + <1131660117.7514.57.camel@krb06.tradebot.com> + <13167.1131668008@sss.pgh.pa.us> + <1131749305.14024.32.camel@krb06.tradebot.com> + <22258.1131750131@sss.pgh.pa.us> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Mon, 14 Nov 2005 08:43:30 -0600 +Message-Id: <1131979410.14024.49.camel@krb06.tradebot.com> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.1 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.016 required=5 tests=[AWL=0.015, + UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.016 +X-Spam-Level: +X-Archive-Number: 200511/223 +X-Sequence-Number: 15480 + +On Fri, 2005-11-11 at 18:02 -0500, Tom Lane wrote: +> > There very well could be a pattern in the data which could affect +> > things, however, I'm not sure how to identify it in 100K rows out of +> > 100M. +> +> I conjecture that the problem areas represent places where the key +> sequence is significantly "more random" than it is elsewhere. Hard +> to be more specific than that though. +> + +OK, I understand the pattern now. + +My two tables hold orders, and order state transitions. Most orders +have two transitions: creation and termination. The problem happens +when there is a significant number of orders where termination is +happening a long time after creation, causing order_transition rows with +old ord_id values to be inserted. + +This is valid, so I have to figure out a way to accomodate it. + +You mentioned playing with checkpointing and bgwriter earlier in this +thread. I experimented with the bgwriter through the weekend, but I +don't have a good idea what sensible parameter changes are... + +Re: checkpointing, currently my checkpoints are happening every 5 +minutes (if I turn on fsync, the graph shows checkpoints dramatically). +If I increase the checkpoint_timeout, could that be beneficial? Or +would I just have more time between larger spikes? + +-K + +From pgsql-performance-owner@postgresql.org Mon Nov 14 15:28:36 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 2A9CFDA3E6 + for ; + Mon, 14 Nov 2005 15:28:30 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 86623-05 + for ; + Mon, 14 Nov 2005 19:28:27 +0000 (GMT) +X-Greylist: delayed 03:16:12.37411 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 7985ADB685 + for ; + Mon, 14 Nov 2005 15:28:27 -0400 (AST) +Received: from tiere.net.avaya.com (tiere.net.avaya.com [198.152.12.100]) + by svr2.postgresql.org (Postfix) with ESMTP id E20E9F0BB1 + for ; + Mon, 14 Nov 2005 16:12:13 +0000 (GMT) +Received: from tiere.net.avaya.com (localhost [127.0.0.1]) + by tiere.net.avaya.com (Switch-3.1.2/Switch-3.1.0) with ESMTP id + jAEG9I4P027540 for ; + Mon, 14 Nov 2005 11:09:18 -0500 (EST) +Received: from nj7460avexu2.global.avaya.com (h198-152-6-52.avaya.com + [198.152.6.52]) + by tiere.net.avaya.com (Switch-3.1.2/Switch-3.1.0) with ESMTP id + jAEG7R4P024792 for ; + Mon, 14 Nov 2005 11:07:40 -0500 (EST) +X-MimeOLE: Produced By Microsoft Exchange V6.0.6603.0 +content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: multipart/alternative; + boundary="----_=_NextPart_001_01C5E930.EEB0B5EC" +Subject: Postgres recovery time +Date: Mon, 14 Nov 2005 10:34:42 -0500 +Message-ID: + <16F9BDD39536704DA7BFB3172BF191720355ED84@nj7460avexu2.global.avaya.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: Postgres recovery time +Thread-Index: AcXpMLjjZt0a1r37Rwm/5vwZVfAf/Q== +From: "Piccarello, James (James)" +To: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[HTML_MESSAGE=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/226 +X-Sequence-Number: 15483 + +This is a multi-part message in MIME format. + +------_=_NextPart_001_01C5E930.EEB0B5EC +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: quoted-printable + +Does anyone know what factors affect the recovery time of postgres if it = +does not shutdown cleanly? With the same size database I've seen times = +from a few seconds to a few minutes. The longest time was 33 minutes. = +The 33 minutes was after a complete system crash and reboot so there are = +a lot of other things going on as well. 125 seconds was the longest time = +I could reproduce by just doing a kill -9 on postmaster.=20 + +Is it the size of the transaction log? The dead space in files?=20 + +I'm running postges 7.3.4 in Red Hat 8.0. Yes, yes I know it's crazy but = +for a variety of reasons upgrading is not currently feasible. + +Jim + + +------_=_NextPart_001_01C5E930.EEB0B5EC +Content-Type: text/html; + charset="iso-8859-1" +Content-Transfer-Encoding: quoted-printable + + + + + + +Postgres recovery time + + + + +

Does anyone know what factors affect = +the recovery time of postgres if it does not shutdown cleanly? With the = +same size database I've seen  times from a few seconds to a few = +minutes. The longest time was 33 minutes. The 33 minutes was after a = +complete system crash and reboot so there are a lot of other things = +going on as well. 125 seconds was the longest time I could reproduce by = +just doing a kill -9 on postmaster.

+ +

Is it the size of the transaction log? = +The dead space in files? +

+ +

I'm running postges 7.3.4 in Red Hat = +8.0. Yes, yes I know it's crazy but for a variety of reasons upgrading = +is not currently feasible.

+ +

Jim +

+ + + +------_=_NextPart_001_01C5E930.EEB0B5EC-- + +From pgsql-performance-owner@postgresql.org Mon Nov 14 11:57:51 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A1834D9BAD + for ; + Mon, 14 Nov 2005 11:57:49 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 01813-01 + for ; + Mon, 14 Nov 2005 15:57:45 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id BF982D9443 + for ; + Mon, 14 Nov 2005 11:57:47 -0400 (AST) +Received: from smtpauth02.mail.atl.earthlink.net + (smtpauth02.mail.atl.earthlink.net [209.86.89.62]) + by svr2.postgresql.org (Postfix) with ESMTP id AAEBDF0C46 + for ; + Mon, 14 Nov 2005 15:57:52 +0000 (GMT) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; + d=earthlink.net; + b=UuPDBMxSoiOxKdAWi+Oh5UpC1VnF7YhP7GL/9RBSNoi9/PfqZmzA4jPs9heWFD5w; + h=Received:Message-Id:X-Mailer:Date:To:From:Subject:Cc:In-Reply-To:References:Mime-Version:Content-Type:X-ELNK-Trace:X-Originating-IP; +Received: from [70.22.226.16] (helo=ron-6d52adff2a6.earthlink.net) + by smtpauth02.mail.atl.earthlink.net with asmtp (Exim 4.34) + id 1EbgiK-0002xb-6u; Mon, 14 Nov 2005 10:57:48 -0500 +Message-Id: <6.2.5.6.0.20051114104706.01dcf728@earthlink.net> +X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6 +Date: Mon, 14 Nov 2005 10:57:42 -0500 +To: Kelly Burkhart , + pgsql-performance@postgresql.org +From: Ron +Subject: Re: 8.x index insert performance +Cc: pgsql-performance@postgresql.org +In-Reply-To: <1131979410.14024.49.camel@krb06.tradebot.com> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD725@Herge.rcsinc.local> + <20051031193547.GA3311@mark.mielke.cc> + <18647.1130790629@sss.pgh.pa.us> + <1130792391.7026.55.camel@krb06.tradebot.com> + <19065.1130793527@sss.pgh.pa.us> + <1130852029.7026.88.camel@krb06.tradebot.com> + <24845.1130852730@sss.pgh.pa.us> + <1131660117.7514.57.camel@krb06.tradebot.com> + <13167.1131668008@sss.pgh.pa.us> + <1131749305.14024.32.camel@krb06.tradebot.com> + <22258.1131750131@sss.pgh.pa.us> + <1131979410.14024.49.camel@krb06.tradebot.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset="us-ascii"; format=flowed +X-ELNK-Trace: + acd68a6551193be5d780f4a490ca69563f9fea00a6dd62bc3fdc3a5e2ac505c4707c912fb9379aed350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c +X-Originating-IP: 70.22.226.16 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.479 required=5 tests=[DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.479 +X-Spam-Level: +X-Archive-Number: 200511/224 +X-Sequence-Number: 15481 + +At 09:43 AM 11/14/2005, Kelly Burkhart wrote: +>On Fri, 2005-11-11 at 18:02 -0500, Tom Lane wrote: +> > > There very well could be a pattern in the data which could affect +> > > things, however, I'm not sure how to identify it in 100K rows out of +> > > 100M. +> > +> > I conjecture that the problem areas represent places where the key +> > sequence is significantly "more random" than it is elsewhere. Hard +> > to be more specific than that though. +> > +> +>OK, I understand the pattern now. +> +>My two tables hold orders, and order state transitions. Most orders +>have two transitions: creation and termination. The problem happens +>when there is a significant number of orders where termination is +>happening a long time after creation, causing order_transition rows with +>old ord_id values to be inserted. +> +>This is valid, so I have to figure out a way to accomodate it. +Perhaps a small schema change would help? Instead of having the +order state transitions explicitly listed in the table, why not +create two new tables; 1 for created orders and 1 for terminated +orders. When an order is created, its ord_id goes into the +CreatedOrders table. When an order is terminated, its ord_id is +added to the TerminatedOrders table and then deleted from the +CreatedOrders table. + +Downsides to this approach are some extra complexity and that you +will have to make sure that system disaster recovery includes making +sure that no ord_id appears in both the CreatedOrders and +TerminatedOrdes tables. Upsides are that the insert problem goes +away and certain kinds of accounting and inventory reports are now +easier to create. + +Ron + + + +From pgsql-performance-owner@postgresql.org Mon Nov 14 14:53:41 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5A781D8CBA + for ; + Mon, 14 Nov 2005 14:53:40 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 39590-07 + for ; + Mon, 14 Nov 2005 18:53:37 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mtiwmhc13.worldnet.att.net (mtiwmhc13.worldnet.att.net + [204.127.131.117]) + by svr1.postgresql.org (Postfix) with ESMTP id 0D1FDD8A5B + for ; + Mon, 14 Nov 2005 14:53:37 -0400 (AST) +Received: from [10.10.100.50] (unknown[216.113.237.29]) + by worldnet.att.net (mtiwmhc13) with ESMTP + id <2005111418533811300sk7o4e>; Mon, 14 Nov 2005 18:53:38 +0000 +Message-ID: <4378DD34.4080706@att.net> +Date: Mon, 14 Nov 2005 13:53:40 -0500 +From: DW +Reply-To: dwinner-lists@att.net +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: slow queries after ANALYZE +References: <4374EDF1.5010709@att.net> +In-Reply-To: <4374EDF1.5010709@att.net> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.027 required=5 tests=[AWL=0.027] +X-Spam-Score: 0.027 +X-Spam-Level: +X-Archive-Number: 200511/225 +X-Sequence-Number: 15482 + +DW wrote: +> Hello, +> +> I'm perplexed. I'm trying to find out why some queries are taking a long +> time, and have found that after running analyze, one particular query +> becomes slow. +> +> This query is based on a view that is based on multiple left outer joins +> to merge data from lots of tables. +> +> If I drop the database and reload it from a dump, the query result is +> instaneous (less than one second). +> +> But after I run analyze, it then takes much longer to run -- about 10 +> seconds, give or take a few depending on the hardware I'm testing it on. +> Earlier today, it was taking almost 30 seconds on the actual production +> server -- I restarted pgsql server and the time got knocked down to +> about 10 seconds -- another thing I don't understand. +> +> I've run the query a number of times before and after running analyze, +> and the problem reproduces everytime. I also ran with "explain", and saw +> that the costs go up dramatically after I run analyze. +> +> I'm fairly new to postgresql and not very experienced as a db admin to +> begin with, but it looks like I'm going to have to get smarter about +> this stuff fast, unless it's something the programmers need to deal with +> when constructing their code and queries or designing the databases. +> +> I've already learned that I've commited the cardinal sin of configuring +> my new database server with RAID 5 instead of something more sensible +> for databases like 0+1, but I've been testing out and replicating this +> problem on different hardware, so I know that this issue is not the +> direct cause of this. +> +> Thanks for any info. I can supply more info (like config files, schemas, +> etc.) if you think it might help. But I though I would just describe the +> problem for starters. +> +> -DW +> +Well, for whatever it's worth, on my test box, I upgraded from postgreql +7.4.9 to 8.1, and that seems to make all the difference in the world. + +These complex queries are instantaneous, and the query planner when I +run EXPLAIN ANALYZE both before and after running ANALYZE displays +results more in line with what is expected (< 60ms). + +Whatever changes were introduced in 8.x seems to make a huge improvment +in query performance. + + + + +> + + +From pgsql-performance-owner@postgresql.org Mon Nov 14 19:54:36 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 4466FDB808 + for ; + Mon, 14 Nov 2005 19:54:18 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 28683-07-6 + for ; + Mon, 14 Nov 2005 23:54:11 +0000 (GMT) +X-Greylist: delayed 02:12:39.802749 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 4483EDB7DF + for ; + Mon, 14 Nov 2005 19:54:06 -0400 (AST) +Received: from toad.mtbrook.bozemanpass.com (toad.mtbrook.bozemanpass.com + [69.145.82.195]) + by svr2.postgresql.org (Postfix) with ESMTP id E9CB9F0B6E + for ; + Mon, 14 Nov 2005 21:41:27 +0000 (GMT) +Received: from [69.145.82.218] (unknown [69.145.82.218]) + by toad.mtbrook.bozemanpass.com (Postfix) with ESMTP id 45BBE1102E6; + Mon, 14 Nov 2005 13:41:22 -0800 (PST) +Message-ID: <43790489.4030803@boreham.org> +Date: Mon, 14 Nov 2005 14:41:29 -0700 +From: David Boreham +Reply-To: david_list@boreham.org +User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: "Piccarello, James (James)" +Cc: pgsql-performance@postgresql.org +Subject: Re: Postgres recovery time +References: + <16F9BDD39536704DA7BFB3172BF191720355ED84@nj7460avexu2.global.avaya.com> +In-Reply-To: + <16F9BDD39536704DA7BFB3172BF191720355ED84@nj7460avexu2.global.avaya.com> +Content-Type: multipart/alternative; + boundary="------------000108060204090205000808" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[HTML_MESSAGE=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/233 +X-Sequence-Number: 15490 + +This is a multi-part message in MIME format. +--------------000108060204090205000808 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit + +Piccarello, James (James) wrote: + +> Does anyone know what factors affect the recovery time of postgres if +> it does not shutdown cleanly? With the same size database I've seen +> times from a few seconds to a few minutes. The longest time was 33 +> minutes. The 33 minutes was after a complete system crash and reboot +> so there are a lot of other things going on as well. 125 seconds was +> the longest time I could reproduce by just doing a kill -9 on postmaster. +> +> Is it the size of the transaction log? The dead space in files? +> +I don't know much about postgresql, but typically WAL mechanisms +will exhibit recovery times that are bounded by the amount of log record +data written since the last checkpoint. The 'worst' case will be where +you have continuous writes to the database and a long checkpoint +interval. In that case many log records must be replayed into the +data files upon recovery. The 'best' case would be zero write transactions +since the last checkpoint. In that case recovery would be swift since +there are no live records to recover. In your tests you are probably +exercising this 'best' or near best case. + + + +--------------000108060204090205000808 +Content-Type: text/html; charset=ISO-8859-1 +Content-Transfer-Encoding: 7bit + + + + + + + + +Piccarello, James (James) wrote: +
+ + + Postgres recovery time + +

Does anyone know what factors affect +the recovery time of postgres if it does not shutdown cleanly? With the +same size database I've seen  times from a few seconds to a few +minutes. The longest time was 33 minutes. The 33 minutes was after a +complete system crash and reboot so there are a lot of other things +going on as well. 125 seconds was the longest time I could reproduce by +just doing a kill -9 on postmaster.

+

Is it the size of the transaction log? +The dead space in files? +

+
+I don't know much about postgresql, +but typically WAL mechanisms
+will exhibit recovery times that are bounded by the amount of log record
+data written since the last checkpoint. The 'worst' case will be where
+you have continuous writes to the database and a long checkpoint
+interval. In that case many log records must be replayed into the
+data files upon recovery. The 'best' case would be zero write +transactions
+since the last checkpoint. In that case recovery would be swift since
+there are no live records to recover. In your tests you are probably
+exercising this 'best' or near best case.
+
+
+ + + + +--------------000108060204090205000808-- + +From pgsql-performance-owner@postgresql.org Mon Nov 14 19:07:25 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id C0295DB6F4 + for ; + Mon, 14 Nov 2005 19:07:23 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 01122-01 + for ; + Mon, 14 Nov 2005 23:07:20 +0000 (GMT) +X-Greylist: delayed 00:59:59.888063 by SQLgrey- +Received: from noao.edu (noao.edu [140.252.1.54]) + by svr1.postgresql.org (Postfix) with ESMTP id 07227DB6AA + for ; + Mon, 14 Nov 2005 19:07:21 -0400 (AST) +X-TFF-CGPSA-Version: 1.4f1 +X-TFF-CGPSA-Filter: Scanned +Received: from weaver.tuc.noao.edu ([140.252.14.8] verified) + by noao.edu (CommuniGate Pro SMTP 5.0.1) + with ESMTPS id 21634304; Mon, 14 Nov 2005 15:07:21 -0700 +Received: from [127.0.0.1] (localhost.localdomain [127.0.0.1]) + by weaver.tuc.noao.edu (8.13.1/8.13.1) with ESMTP id jAEM7LCo030131; + Mon, 14 Nov 2005 15:07:21 -0700 +Message-ID: <43790A99.9050603@noao.edu> +Date: Mon, 14 Nov 2005 15:07:21 -0700 +From: Steve Wampler +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Postgres-performance +Subject: Help speeding up delete +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.005 required=5 tests=[AWL=0.005] +X-Spam-Score: 0.005 +X-Spam-Level: +X-Archive-Number: 200511/227 +X-Sequence-Number: 15484 + + +We've got an older system in production (PG 7.2.4). Recently +one of the users has wanted to implement a selective delete, +but is finding that the time it appears to take exceeds her +patience factor by several orders of magnitude. Here's +a synopsis of her report. It appears that the "WHERE +id IN ..." is resulting in a seq scan that is causing +the problem, but we're not SQL expert enough to know +what to do about it. + +Can someone point out what we're doing wrong, or how we +could get a (much) faster delete? Thanks! + +Report: +============================================================ +This command yields results in only a few seconds: + +# SELECT at.id FROM "tmp_table2" at, "tmp_tabl2e" a +# WHERE at.id=a.id and a.name='obsid' and a.value='oid080505'; + +However, the following command does not seen to want to ever +complete (the person running this killed it after 1/2 hour). + +# DELETE FROM "tmp_table2" WHERE id IN +# (SELECT at.id FROM "tmp_table2" at, "tmp_table2" a +# WHERE at.id=a.id and a.name='obsid' and a.value='oid080505'); + +============================================================== + +The table has four columns. There are 6175 rows satifying the condition +given, and the table itself has 1539688 entries. Layout is: + +lab.devel.configdb=# \d tmp_table2 + Table "tmp_table2" + Column | Type | Modifiers +--------+--------------------------+----------- + id | character varying(64) | + name | character varying(64) | + units | character varying(32) | + value | text | + time | timestamp with time zone | + +============================================================== + +lab.devel.configdb=# EXPLAIN DELETE FROM "tmp_table2" WHERE id IN +lab.devel.configdb-# (SELECT at.id FROM "tmp_table2" at, "tmp_table2" a +lab.devel.configdb(# WHERE at.id=a.id AND a.name='obsid' AND a.value='oid080505'); +NOTICE: QUERY PLAN: + +Seq Scan on tmp_table2 (cost=0.00..154893452082.10 rows=769844 width=6) + SubPlan + -> Materialize (cost=100600.52..100600.52 rows=296330 width=100) + -> Hash Join (cost=42674.42..100600.52 rows=296330 width=100) + -> Seq Scan on tmp_table2 at (cost=0.00..34975.88 rows=1539688 width=50) + -> Hash (cost=42674.32..42674.32 rows=38 width=50) + -> Seq Scan on tmp_table2 a (cost=0.00..42674.32 rows=38 width=50) +EXPLAIN + +lab.devel.configdb=# EXPLAIN (SELECT at.id FROM "tmp_table2" at, "tmp_table2" a +lab.devel.configdb(# WHERE at.id=a.id AND a.name='obsid' AND a.value='oid080505'); +NOTICE: QUERY PLAN: + +Hash Join (cost=42674.42..100600.52 rows=296330 width=100) + -> Seq Scan on tmp_table2 at (cost=0.00..34975.88 rows=1539688 width=50) + -> Hash (cost=42674.32..42674.32 rows=38 width=50) + -> Seq Scan on tmp_table2 a (cost=0.00..42674.32 rows=38 width=50) + +EXPLAIN + +-- +Steve Wampler -- swampler@noao.edu +The gods that smiled on your birth are now laughing out loud. + +From pgsql-performance-owner@postgresql.org Mon Nov 14 19:20:25 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A107FDB77A + for ; + Mon, 14 Nov 2005 19:20:24 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 11371-03 + for ; + Mon, 14 Nov 2005 23:20:19 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from calvin.slamb.org (calvin.slamb.org [216.136.66.56]) + by svr1.postgresql.org (Postfix) with ESMTP id 400C6DA720 + for ; + Mon, 14 Nov 2005 19:20:20 -0400 (AST) +Received: by calvin.slamb.org (Postfix, from userid 103) + id AC5436FD1F; Mon, 14 Nov 2005 17:20:23 -0600 (CST) +Received: from [IPv6:::1] (localhost.slamb.org [127.0.0.1]) + by calvin.slamb.org (Postfix) with ESMTP + id 6FE3D6FCA2; Mon, 14 Nov 2005 17:20:22 -0600 (CST) +In-Reply-To: <43790A99.9050603@noao.edu> +References: <43790A99.9050603@noao.edu> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: text/plain; charset=US-ASCII; format=flowed +Message-Id: <5E90D296-FA4A-4E48-92B4-396AADE35EF2@slamb.org> +Cc: Postgres-performance +Content-Transfer-Encoding: 7bit +From: Scott Lamb +Subject: Re: Help speeding up delete +Date: Mon, 14 Nov 2005 15:20:21 -0800 +To: Steve Wampler +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/228 +X-Sequence-Number: 15485 + +On Nov 14, 2005, at 2:07 PM, Steve Wampler wrote: +> # SELECT at.id FROM "tmp_table2" at, "tmp_tabl2e" a +> # WHERE at.id=a.id and a.name='obsid' and a.value='oid080505'; + +Isn't this equivalent? + +select id from tmp_table2 where name = 'obsid' and value = 'oid080505'; + +> # DELETE FROM "tmp_table2" WHERE id IN +> # (SELECT at.id FROM "tmp_table2" at, "tmp_table2" a +> # WHERE at.id=a.id and a.name='obsid' and a.value='oid080505'); + +and this? + +delete from tmp_table2 where name = 'obsid' and value = 'oid080505'; + +Why are you doing a self-join using id, which I assume is a primary key? + +-- +Scott Lamb + + + +From pgsql-performance-owner@postgresql.org Mon Nov 14 19:42:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 912A2DB758 + for ; + Mon, 14 Nov 2005 19:42:44 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 26651-05 + for ; + Mon, 14 Nov 2005 23:42:41 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 5816EDB715 + for ; + Mon, 14 Nov 2005 19:42:43 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAENghuu004163; + Mon, 14 Nov 2005 18:42:43 -0500 (EST) +To: Steve Wampler +cc: Postgres-performance +Subject: Re: Help speeding up delete +In-reply-to: <43790A99.9050603@noao.edu> +References: <43790A99.9050603@noao.edu> +Comments: In-reply-to Steve Wampler + message dated "Mon, 14 Nov 2005 15:07:21 -0700" +Date: Mon, 14 Nov 2005 18:42:43 -0500 +Message-ID: <4162.1132011763@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/229 +X-Sequence-Number: 15486 + +Steve Wampler writes: +> We've got an older system in production (PG 7.2.4). Recently +> one of the users has wanted to implement a selective delete, +> but is finding that the time it appears to take exceeds her +> patience factor by several orders of magnitude. Here's +> a synopsis of her report. It appears that the "WHERE +> id IN ..." is resulting in a seq scan that is causing +> the problem, but we're not SQL expert enough to know +> what to do about it. + +> Can someone point out what we're doing wrong, or how we +> could get a (much) faster delete? Thanks! + +Update to 7.4 or later ;-) + +Quite seriously, if you're still using 7.2.4 for production purposes +you could justifiably be accused of negligence. There are three or four +data-loss-grade bugs fixed in the later 7.2.x releases, not to mention +security holes; and that was before we abandoned support for 7.2. +You *really* need to be thinking about an update. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Mon Nov 14 19:54:36 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0016ADB7B4 + for ; + Mon, 14 Nov 2005 19:54:17 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 24131-04-5 + for ; + Mon, 14 Nov 2005 23:54:08 +0000 (GMT) +X-Greylist: delayed 00:07:28.061495 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 42BB9DB7D9 + for ; + Mon, 14 Nov 2005 19:54:04 -0400 (AST) +Received: from seiumain.SEIU.local (unknown [204.107.254.246]) + by svr2.postgresql.org (Postfix) with ESMTP id DA9CFF0E1D + for ; + Mon, 14 Nov 2005 23:46:39 +0000 (GMT) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: multipart/alternative; + boundary="----_=_NextPart_001_01C5E975.A9925674" +Subject: Hardware/OS recommendations for large databases (5TB) +X-MimeOLE: Produced By Microsoft Exchange V6.5 +Date: Mon, 14 Nov 2005 18:46:41 -0500 +Message-ID: <1B80C974ABFB23429A403B6667FE84C71066E8@seiumain.SEIU.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: Hardware/OS recommendations for large databases (5TB) +Thread-Index: AcXpda8A8NHotzO6TfG+EL6U5TQ8/g== +From: "Adam Weisberg" +To: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[HTML_MESSAGE=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/232 +X-Sequence-Number: 15489 + +This is a multi-part message in MIME format. + +------_=_NextPart_001_01C5E975.A9925674 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable + +Does anyone have recommendations for hardware and/or OS to work with +around 5TB datasets?=20 +=20 +The data is for analysis, so there is virtually no inserting besides a +big bulk load. Analysis involves full-database aggregations - mostly +basic arithmetic and grouping. In addition, much smaller subsets of data +would be pulled and stored to separate databases. +=20 +I have been working with datasets no bigger than around 30GB, and that +(I'm afraid to admit) has been in MSSQL. +=20 +Thanks, +=20 +Adam + +------_=_NextPart_001_01C5E975.A9925674 +Content-Type: text/html; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable + + + + + + +
Does = +anyone have=20 +recommendations for hardware and/or OS to work with around 5TB datasets? = + +
+
 
+
The = +data is for=20 +analysis, so there is virtually no inserting besides a big bulk=20 +load.=20 +Analysis involves full-database aggregations - mostly basic = +arithmetic and=20 +grouping. In addition, much smaller subsets of data would be pulled = +and=20 +stored to separate databases.
+
 
+
I = +have been=20 +working with datasets no bigger than around 30GB, and that (I'm=20 +afraid to admit) has been in MSSQL.
+
 
+
Thanks,
+
 
+
Adam
+ +------_=_NextPart_001_01C5E975.A9925674-- + +From pgsql-performance-owner@postgresql.org Mon Nov 14 19:51:16 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id F190ED9FD6 + for ; + Mon, 14 Nov 2005 19:51:15 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 18163-09 + for ; + Mon, 14 Nov 2005 23:51:10 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from net2.micro-automation.com (net2.micro-automation.com + [64.7.141.29]) + by svr1.postgresql.org (Postfix) with SMTP id 6C762D9D64 + for ; + Mon, 14 Nov 2005 19:51:11 -0400 (AST) +Received: (qmail 8504 invoked from network); 14 Nov 2005 23:51:11 -0000 +Received: from dcdsl.ebox.com (HELO ?192.168.1.2?) (davec@64.7.143.116) + by net2.micro-automation.com with SMTP; 14 Nov 2005 23:51:11 -0000 +In-Reply-To: <1131283854.15471.4.camel@Panoramix> +References: <1131283854.15471.4.camel@Panoramix> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: +Cc: Pgsql-Performance +Content-Transfer-Encoding: 7bit +From: Dave Cramer +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware Raid5 / Debian?? +Date: Mon, 14 Nov 2005 18:51:09 -0500 +To: Joost Kraaijeveld +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.022 required=5 tests=[AWL=0.022] +X-Spam-Score: 0.022 +X-Spam-Level: +X-Archive-Number: 200511/230 +X-Sequence-Number: 15487 + +Joost, + +I've got experience with these controllers and which version do you +have. I'd expect to see higher than 50MB/s although I've never tried +RAID 5 + +I routinely see closer to 100MB/s with RAID 1+0 on their 9000 series + +I would also suggest that shared buffers should be higher than 7500, +closer to 30000, and effective cache should be up around 200k + +work_mem is awfully high, remember that this will be given to each +and every connection and can be more than 1x this number per +connection depending on the number of sorts +done in the query. + +fsync=false ? I'm not even sure why we have this option, but I'd +never set it to false. + +Dave + +On 6-Nov-05, at 8:30 AM, Joost Kraaijeveld wrote: + +> Hi, +> +> I am experiencing very long update queries and I want to know if it +> reasonable to expect them to perform better. +> +> The query below is running for more than 1.5 hours (5500 seconds) now, +> while the rest of the system does nothing (I don't even type or move a +> mouse...). +> +> - Is that to be expected? +> - Is 180-200 tps with ~ 9000 KB (see output iostat below) not low, +> given +> the fact that fsync is off? (Note: with bonnie++ I get write +> performance > 50 MB/sec and read performace > 70 MB/sec with > 2000 +> read/write ops /sec? +> - Does anyone else have any experience with the 3Ware RAID controller +> (which is my suspect)? +> - Any good idea how to determine the real botleneck if this is not the +> performance I can expect? +> +> My hard- and software: +> +> - PostgreSQL 8.0.3 +> - Debian 3.1 (Sarge) AMD64 +> - Dual Opteron +> - 4GB RAM +> - 3ware Raid5 with 5 disks +> +> Pieces of my postgresql.conf (All other is default): +> shared_buffers = 7500 +> work_mem = 260096 +> fsync=false +> effective_cache_size = 32768 +> +> +> +> The query with explain (amount and orderbedrag_valuta are float8, +> ordernummer and ordernumber int4): +> +> explain update prototype.orders set amount = +> odbc.orders.orderbedrag_valuta from odbc.orders where ordernumber = +> odbc.orders.ordernummer; +> QUERY PLAN +> ---------------------------------------------------------------------- +> ------- +> Hash Join (cost=50994.74..230038.17 rows=1104379 width=466) +> Hash Cond: ("outer".ordernumber = "inner".ordernummer) +> -> Seq Scan on orders (cost=0.00..105360.68 rows=3991868 +> width=455) +> -> Hash (cost=48233.79..48233.79 rows=1104379 width=15) +> -> Seq Scan on orders (cost=0.00..48233.79 rows=1104379 +> width=15) +> +> +> Sample output from iostat during query (about avarage): +> Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn +> hdc 0.00 0.00 0.00 0 0 +> sda 0.00 0.00 0.00 0 0 +> sdb 187.13 23.76 8764.36 24 8852 +> +> +> -- +> Groeten, +> +> Joost Kraaijeveld +> Askesis B.V. +> Molukkenstraat 14 +> 6524NB Nijmegen +> tel: 024-3888063 / 06-51855277 +> fax: 024-3608416 +> e-mail: J.Kraaijeveld@Askesis.nl +> web: www.askesis.nl +> +> +> +> ---------------------------(end of +> broadcast)--------------------------- +> TIP 1: if posting/reading through Usenet, please send an appropriate +> subscribe-nomail command to majordomo@postgresql.org so that +> your +> message can get through to the mailing list cleanly +> + + +From pgsql-performance-owner@postgresql.org Mon Nov 14 19:52:55 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CD41DDB685 + for ; + Mon, 14 Nov 2005 19:52:54 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 29819-05 + for ; + Mon, 14 Nov 2005 23:52:51 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from noao.edu (noao.edu [140.252.1.54]) + by svr1.postgresql.org (Postfix) with ESMTP id 3D34EDAA96 + for ; + Mon, 14 Nov 2005 19:52:53 -0400 (AST) +X-TFF-CGPSA-Version: 1.4f1 +X-TFF-CGPSA-Filter: Scanned +Received: from weaver.tuc.noao.edu ([140.252.14.8] verified) + by noao.edu (CommuniGate Pro SMTP 5.0.1) + with ESMTPS id 21636207; Mon, 14 Nov 2005 16:52:55 -0700 +Received: from [127.0.0.1] (localhost.localdomain [127.0.0.1]) + by weaver.tuc.noao.edu (8.13.1/8.13.1) with ESMTP id jAENqrpv000541; + Mon, 14 Nov 2005 16:52:54 -0700 +Message-ID: <43792355.1020501@noao.edu> +Date: Mon, 14 Nov 2005 16:52:53 -0700 +From: Steve Wampler +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Scott Lamb +CC: Postgres-performance +Subject: Re: Help speeding up delete +References: <43790A99.9050603@noao.edu> + <5E90D296-FA4A-4E48-92B4-396AADE35EF2@slamb.org> +In-Reply-To: <5E90D296-FA4A-4E48-92B4-396AADE35EF2@slamb.org> +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.005 required=5 tests=[AWL=0.005] +X-Spam-Score: 0.005 +X-Spam-Level: +X-Archive-Number: 200511/231 +X-Sequence-Number: 15488 + +Scott Lamb wrote: +> On Nov 14, 2005, at 2:07 PM, Steve Wampler wrote: +> +>> # SELECT at.id FROM "tmp_table2" at, "tmp_tabl2e" a +>> # WHERE at.id=a.id and a.name='obsid' and a.value='oid080505'; +> +> +> Isn't this equivalent? +> +> select id from tmp_table2 where name = 'obsid' and value = 'oid080505'; + +Probably, the user based the above on a query designed to find +all rows with the same id as those rows that have a.name='obsid' and +a.value='oid080505'. However, I think the above would work to locate +all the ids, which is all we need for the delete (see below) + +>> # DELETE FROM "tmp_table2" WHERE id IN +>> # (SELECT at.id FROM "tmp_table2" at, "tmp_table2" a +>> # WHERE at.id=a.id and a.name='obsid' and a.value='oid080505'); +> +> +> and this? +> +> delete from tmp_table2 where name = 'obsid' and value = 'oid080505'; +> +> Why are you doing a self-join using id, which I assume is a primary key? + +Because I think we need to. The above would only delete rows that have +name = 'obsid' and value = 'oid080505'. We need to delete all rows that +have the same ids as those rows. However, from what you note, I bet +we could do: + + DELETE FROM "tmp_table2" WHERE id IN + (SELECT id FROM "temp_table2" WHERE name = 'obsid' and value= 'oid080505'); + +However, even that seems to have a much higher cost than I'd expect: + + lab.devel.configdb=# explain delete from "tmp_table2" where id in + (select id from tmp_table2 where name='obsid' and value = 'oid080505'); + NOTICE: QUERY PLAN: + + Seq Scan on tmp_table2 (cost=0.00..65705177237.26 rows=769844 width=6) + SubPlan + -> Materialize (cost=42674.32..42674.32 rows=38 width=50) + -> Seq Scan on tmp_table2 (cost=0.00..42674.32 rows=38 width=50) + + EXPLAIN + +And, sure enough, is taking an extrordinarily long time to run (more than +10 minutes so far, compared to < 10seconds for the select). Is this +really typical of deletes? It appears (to me) to be the Seq Scan on tmp_table2 +that is the killer here. If we put an index on, would it help? (The user +claims she tried that and it's EXPLAIN cost went even higher, but I haven't +checked that...) + +Thanks! +-- +Steve Wampler -- swampler@noao.edu +The gods that smiled on your birth are now laughing out loud. + +From pgsql-performance-owner@postgresql.org Mon Nov 14 20:02:58 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id DC810DA3DF + for ; + Mon, 14 Nov 2005 20:00:38 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 44024-01 + for ; + Tue, 15 Nov 2005 00:00:35 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from noao.edu (noao.edu [140.252.1.54]) + by svr1.postgresql.org (Postfix) with ESMTP id 4BF26DA3E6 + for ; + Mon, 14 Nov 2005 20:00:37 -0400 (AST) +X-TFF-CGPSA-Version: 1.4f1 +X-TFF-CGPSA-Filter: Scanned +Received: from weaver.tuc.noao.edu ([140.252.14.8] verified) + by noao.edu (CommuniGate Pro SMTP 5.0.1) + with ESMTPS id 21636357; Mon, 14 Nov 2005 17:00:36 -0700 +Received: from [127.0.0.1] (localhost.localdomain [127.0.0.1]) + by weaver.tuc.noao.edu (8.13.1/8.13.1) with ESMTP id jAF00Zva000706; + Mon, 14 Nov 2005 17:00:36 -0700 +Message-ID: <43792523.5090003@noao.edu> +Date: Mon, 14 Nov 2005 17:00:35 -0700 +From: Steve Wampler +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Tom Lane +CC: Postgres-performance +Subject: Re: Help speeding up delete +References: <43790A99.9050603@noao.edu> <4162.1132011763@sss.pgh.pa.us> +In-Reply-To: <4162.1132011763@sss.pgh.pa.us> +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.005 required=5 tests=[AWL=0.005] +X-Spam-Score: 0.005 +X-Spam-Level: +X-Archive-Number: 200511/234 +X-Sequence-Number: 15491 + +Tom Lane wrote: +> Steve Wampler writes: +> +>>We've got an older system in production (PG 7.2.4). Recently +>>one of the users has wanted to implement a selective delete, +>>but is finding that the time it appears to take exceeds her +>>patience factor by several orders of magnitude. Here's +>>a synopsis of her report. It appears that the "WHERE +>>id IN ..." is resulting in a seq scan that is causing +>>the problem, but we're not SQL expert enough to know +>>what to do about it. +> +> +>>Can someone point out what we're doing wrong, or how we +>>could get a (much) faster delete? Thanks! +> +> +> Update to 7.4 or later ;-) + +I was afraid you'd say that :-) I'm not officially involved in +this project anymore and was hoping for a fix that wouldn't drag +me back in. The security issues aren't a concern because this +DB is *well* hidden from the outside world (it's part of a telescope +control system behind several firewalls with no outside access). +However, the data-loss-grade bugs issue *is* important. We'll +try to do the upgrade as soon as we get some cloudy days to +actually do it! + +Is the performance behavior that we're experiencing a known +problem with 7.2 that has been addressed in 7.4? Or will the +upgrade fix other problems while leaving this one? + +> Quite seriously, if you're still using 7.2.4 for production purposes +> you could justifiably be accused of negligence. There are three or four +> data-loss-grade bugs fixed in the later 7.2.x releases, not to mention +> security holes; and that was before we abandoned support for 7.2. +> You *really* need to be thinking about an update. + +Thanks! +Steve +-- +Steve Wampler -- swampler@noao.edu +The gods that smiled on your birth are now laughing out loud. + +From pgsql-performance-owner@postgresql.org Mon Nov 14 20:10:13 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9E461DB7A9 + for ; + Mon, 14 Nov 2005 20:10:12 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 41912-07 + for ; + Tue, 15 Nov 2005 00:10:09 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.194]) + by svr1.postgresql.org (Postfix) with ESMTP id 3AA00DB7A6 + for ; + Mon, 14 Nov 2005 20:10:11 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id 36so1382023wra + for ; + Mon, 14 Nov 2005 16:10:14 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; + b=ikg1ACjRybQ6Ts8HvcLonNbaKm+Hb3S/37Ou9evBl36fHuFsgDd/ESRcLaDC6jGqNt8QXPjuBMGNtZ4kltI6+FkRpxUv2yZqh+s2xm39CzrS9Dyv+Nr0aTjdpDfjKVPiKSBkNN2abGEBNumL+qCaKpbtGjbNOkqSRM6BECs97EA= +Received: by 10.65.153.12 with SMTP id f12mr6428102qbo; + Mon, 14 Nov 2005 16:10:14 -0800 (PST) +Received: by 10.64.243.11 with HTTP; Mon, 14 Nov 2005 16:10:14 -0800 (PST) +Message-ID: <38242de90511141610j621d9a02r52a1d6f4fc55cb55@mail.gmail.com> +Date: Mon, 14 Nov 2005 17:10:14 -0700 +From: Joshua Marsh +To: Postgres-performance +Subject: Re: Help speeding up delete +In-Reply-To: <43792355.1020501@noao.edu> +MIME-Version: 1.0 +Content-Type: multipart/alternative; + boundary="----=_Part_7809_18807905.1132013414563" +References: <43790A99.9050603@noao.edu> + <5E90D296-FA4A-4E48-92B4-396AADE35EF2@slamb.org> + <43792355.1020501@noao.edu> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[HTML_MESSAGE=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/235 +X-Sequence-Number: 15492 + +------=_Part_7809_18807905.1132013414563 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline + +On 11/14/05, Steve Wampler wrote: + +> However, even that seems to have a much higher cost than I'd expect: +> +> lab.devel.configdb=3D# explain delete from "tmp_table2" where id in +> (select id from tmp_table2 where name=3D'obsid' and value =3D 'oid080505'= +); +> NOTICE: QUERY PLAN: +> +> Seq Scan on tmp_table2 (cost=3D0.00..65705177237.26 rows=3D769844 width= +=3D6) +> SubPlan +> -> Materialize (cost=3D42674.32..42674.32 rows=3D38 width=3D50) +> -> Seq Scan on tmp_table2 (cost=3D0.00..42674.32 rows=3D38 width=3D50) +> + +For one reason or the other, the planner things a sequential scan is the +best solution. Try turning off seq_scan before the query and see if it +changes the plan (set enable_seqscan off;). + +I've seen this problem with sub queries and that usually solves it. + +-- +This E-mail is covered by the Electronic Communications Privacy Act, 18 +U.S.C. 2510-2521 and is legally privileged. + +This information is confidential information and is intended only for the +use of the individual or entity named above. If the reader of this message +is not the intended recipient, you are hereby notified that any +dissemination, distribution or copying of this communication is strictly +prohibited. + +------=_Part_7809_18807905.1132013414563 +Content-Type: text/html; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline + +

On 11/14/05, Steve Wampler <swample= +r@noao.edu> wrote:
+However, even that seems to have a much higher cost than I'd expect:
   lab.devel.configdb=3D# explain delete from "tmp_table2&q= +uot; where id in
        (select= + id from tmp_table2 where name=3D'obsid' and value =3D 'oid080505'); +
   NOTICE:  QUERY PLAN:

   Seq Sca= +n on tmp_table2  (cost=3D0.00..65705177237.26 rows=3D769844 width= +=3D6)
     SubPlan
     = +  ->  Materialize  (cost=3D42674.32..42674.32 r= +ows=3D38 width=3D50)
        &nb= +sp;    +->  Seq Scan on tmp_table2  (cost=3D0.00..42674.32 +rows=3D38 width=3D50)

+For one reason or the other, the planner things a sequential scan is +the best solution. Try turning off seq_scan before the query and see if +it changes the plan (set enable_seqscan off;). 
+
+I've seen this problem with sub queries and that usually solves it.
+
--
This E-mail is covered by the Electronic Communications Privacy = +Act, 18 U.S.C. 2510-2521 and is legally privileged.

This +information is confidential information and is intended only for the +use of the individual or entity named above. If the reader of this +message is not the intended recipient, you are hereby notified that any +dissemination, distribution or copying of this communication is +strictly prohibited. + +------=_Part_7809_18807905.1132013414563-- + +From pgsql-performance-owner@postgresql.org Mon Nov 14 20:28:22 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id BC6C8DB78D + for ; + Mon, 14 Nov 2005 20:28:20 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 56452-05 + for ; + Tue, 15 Nov 2005 00:28:17 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from noao.edu (noao.edu [140.252.1.54]) + by svr1.postgresql.org (Postfix) with ESMTP id E40F2DB774 + for ; + Mon, 14 Nov 2005 20:28:18 -0400 (AST) +X-TFF-CGPSA-Version: 1.4f1 +X-TFF-CGPSA-Filter: Scanned +Received: from weaver.tuc.noao.edu ([140.252.14.8] verified) + by noao.edu (CommuniGate Pro SMTP 5.0.1) + with ESMTPS id 21636820; Mon, 14 Nov 2005 17:28:19 -0700 +Received: from [127.0.0.1] (localhost.localdomain [127.0.0.1]) + by weaver.tuc.noao.edu (8.13.1/8.13.1) with ESMTP id jAF0SJc5001260; + Mon, 14 Nov 2005 17:28:19 -0700 +Message-ID: <43792BA3.3060702@noao.edu> +Date: Mon, 14 Nov 2005 17:28:19 -0700 +From: Steve Wampler +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Postgres-performance +Subject: Re: Help speeding up delete +References: <43790A99.9050603@noao.edu> + <5E90D296-FA4A-4E48-92B4-396AADE35EF2@slamb.org> + <43792355.1020501@noao.edu> + <38242de90511141610j621d9a02r52a1d6f4fc55cb55@mail.gmail.com> +In-Reply-To: <38242de90511141610j621d9a02r52a1d6f4fc55cb55@mail.gmail.com> +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.004 required=5 tests=[AWL=0.004] +X-Spam-Score: 0.004 +X-Spam-Level: +X-Archive-Number: 200511/236 +X-Sequence-Number: 15493 + +Joshua Marsh wrote: +> +> +> On 11/14/05, *Steve Wampler* > wrote: +> +> However, even that seems to have a much higher cost than I'd expect: +> +> lab.devel.configdb=# explain delete from "tmp_table2" where id in +> (select id from tmp_table2 where name='obsid' and value = +> 'oid080505'); +> NOTICE: QUERY PLAN: +> +> Seq Scan on tmp_table2 (cost=0.00..65705177237.26 rows=769844 +> width=6) +> SubPlan +> -> Materialize (cost=42674.32..42674.32 rows=38 width=50) +> -> Seq Scan on tmp_table2 (cost=0.00..42674.32 +> rows=38 width=50) +> +> +> For one reason or the other, the planner things a sequential scan is the +> best solution. Try turning off seq_scan before the query and see if it +> changes the plan (set enable_seqscan off;). +> +> I've seen this problem with sub queries and that usually solves it. +> + +Hmmm, not only does it still use sequential scans, it thinks it'll take +even longer: + + set enable_seqscan to off; + SET VARIABLE + explain delete from "tmp_table2" where id in + (select id from tmp_table2 where name='obsid' and value = 'oid080505'); + NOTICE: QUERY PLAN: + + Seq Scan on tmp_table2 (cost=100000000.00..160237039405992.50 rows=800836 width=6) + SubPlan + -> Materialize (cost=100043604.06..100043604.06 rows=45 width=26) + -> Seq Scan on tmp_table2 (cost=100000000.00..100043604.06 rows=45 width=26) + + EXPLAIN + +But the advice sounds like it *should* have helped... + +-- +Steve Wampler -- swampler@noao.edu +The gods that smiled on your birth are now laughing out loud. + +From pgsql-performance-owner@postgresql.org Mon Nov 14 21:08:06 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id DC6C9D6D8C + for ; + Mon, 14 Nov 2005 21:08:05 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 12476-01 + for ; + Tue, 15 Nov 2005 01:08:02 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from calvin.slamb.org (calvin.slamb.org [216.136.66.56]) + by svr1.postgresql.org (Postfix) with ESMTP id 535C9DB77F + for ; + Mon, 14 Nov 2005 21:08:03 -0400 (AST) +Received: by calvin.slamb.org (Postfix, from userid 103) + id 616AB6FD21; Mon, 14 Nov 2005 19:08:07 -0600 (CST) +Received: from [IPv6:::1] (localhost.slamb.org [127.0.0.1]) + by calvin.slamb.org (Postfix) with ESMTP + id C4AC16FCD7; Mon, 14 Nov 2005 19:08:05 -0600 (CST) +In-Reply-To: <43792355.1020501@noao.edu> +References: <43790A99.9050603@noao.edu> + <5E90D296-FA4A-4E48-92B4-396AADE35EF2@slamb.org> + <43792355.1020501@noao.edu> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: +Cc: Postgres-performance +Content-Transfer-Encoding: 7bit +From: Scott Lamb +Subject: Re: Help speeding up delete +Date: Mon, 14 Nov 2005 17:08:03 -0800 +To: Steve Wampler +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/237 +X-Sequence-Number: 15494 + +On Nov 14, 2005, at 3:52 PM, Steve Wampler wrote: +> Scott Lamb wrote: +>> On Nov 14, 2005, at 2:07 PM, Steve Wampler wrote: +>> +>>> # SELECT at.id FROM "tmp_table2" at, "tmp_tabl2e" a +>>> # WHERE at.id=a.id and a.name='obsid' and a.value='oid080505'; +>> +>> +>> Isn't this equivalent? +>> +>> select id from tmp_table2 where name = 'obsid' and value = +>> 'oid080505'; +> +> Probably, the user based the above on a query designed to find +> all rows with the same id as those rows that have a.name='obsid' and +> a.value='oid080505'. + +Well, this indirection is only significant if those two sets can +differ. If (A) you meant "tmp_table2" when you wrote "tmp_tabl2e", so +this is a self-join, and (B) there is a primary key on "id", I don't +think that can ever happen. + +> It appears (to me) to be the Seq Scan on tmp_table2 +> that is the killer here. If we put an index on, would it help? + +On...tmp_table2.id? If it is a primary key, there already is one. If +not, yeah, I expect it would help. + +-- +Scott Lamb + + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 16:43:44 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 91915DB7AD + for ; + Mon, 14 Nov 2005 21:29:27 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 25298-01 + for ; + Tue, 15 Nov 2005 01:29:22 +0000 (GMT) +X-Greylist: delayed 00:10:32.702321 by SQLgrey- +Received: from mail-ihug.icp-qv1-irony3.iinet.net.au + (ihug-mail.icp-qv1-irony3.iinet.net.au [203.59.1.197]) + by svr1.postgresql.org (Postfix) with ESMTP id 9212BDB77F + for ; + Mon, 14 Nov 2005 21:29:23 -0400 (AST) +Received: from 203-214-116-121.dyn.iinet.net.au (HELO [192.168.1.21]) + ([203.214.116.121]) + by mail-ihug.icp-qv1-irony3.iinet.net.au with ESMTP; + 15 Nov 2005 09:18:49 +0800 +X-BrightmailFiltered: true +X-Brightmail-Tracker: AAAAAQAAA+k= +Message-ID: <43793778.7040006@linuxgamers.net> +Date: Tue, 15 Nov 2005 12:18:48 +1100 +From: Leigh Dyer +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Postgres-performance +Subject: Re: Help speeding up delete +References: <43790A99.9050603@noao.edu> <4162.1132011763@sss.pgh.pa.us> + <43792523.5090003@noao.edu> +In-Reply-To: <43792523.5090003@noao.edu> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/382 +X-Sequence-Number: 15639 + +Steve Wampler wrote: +> +> Is the performance behavior that we're experiencing a known +> problem with 7.2 that has been addressed in 7.4? Or will the +> upgrade fix other problems while leaving this one? + +I'm pretty sure that in versions earlier than 7.4, IN clauses that use a +subquery will always use a seqscan, regardless of what indexes are +available. If you try an IN using explicit values though, it should use +the index. + +Thanks +Leigh + +From pgsql-performance-owner@postgresql.org Tue Nov 15 00:04:43 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id BC9A3DB7D1 + for ; + Tue, 15 Nov 2005 00:04:41 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 51677-04 + for ; + Tue, 15 Nov 2005 04:04:01 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from noao.edu (noao.edu [140.252.1.54]) + by svr1.postgresql.org (Postfix) with ESMTP id E8BF4DB77B + for ; + Tue, 15 Nov 2005 00:04:00 -0400 (AST) +X-TFF-CGPSA-Version: 1.4f1 +X-TFF-CGPSA-Filter: Scanned +Received: from weaver.tuc.noao.edu ([140.252.14.8] verified) + by noao.edu (CommuniGate Pro SMTP 5.0.1) + with ESMTPS id 21639674; Mon, 14 Nov 2005 21:03:58 -0700 +Received: from [127.0.0.1] (localhost.localdomain [127.0.0.1]) + by weaver.tuc.noao.edu (8.13.1/8.13.1) with ESMTP id jAF43uGO005497; + Mon, 14 Nov 2005 21:03:57 -0700 +Message-ID: <43795E2C.4040502@noao.edu> +Date: Mon, 14 Nov 2005 21:03:56 -0700 +From: Steve Wampler +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Scott Lamb +CC: Postgres-performance +Subject: Re: Help speeding up delete +References: <43790A99.9050603@noao.edu> + <5E90D296-FA4A-4E48-92B4-396AADE35EF2@slamb.org> + <43792355.1020501@noao.edu> + +In-Reply-To: +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/238 +X-Sequence-Number: 15495 + +Scott Lamb wrote: +> On Nov 14, 2005, at 3:52 PM, Steve Wampler wrote: +> +>> Scott Lamb wrote: +>> +>>> On Nov 14, 2005, at 2:07 PM, Steve Wampler wrote: +>>> +>>>> # SELECT at.id FROM "tmp_table2" at, "tmp_tabl2e" a +>>>> # WHERE at.id=a.id and a.name='obsid' and a.value='oid080505'; +>>> +>>> +>>> +>>> Isn't this equivalent? +>>> +>>> select id from tmp_table2 where name = 'obsid' and value = 'oid080505'; +>> +>> +>> Probably, the user based the above on a query designed to find +>> all rows with the same id as those rows that have a.name='obsid' and +>> a.value='oid080505'. +> +> +> Well, this indirection is only significant if those two sets can +> differ. If (A) you meant "tmp_table2" when you wrote "tmp_tabl2e", so +> this is a self-join, and (B) there is a primary key on "id", I don't +> think that can ever happen. + +I wasn't clear. The original query was: + + SELECT at.* FROM "tmp_table2" at, "tmp_table2" a + WHERE at.id=a.id and a.name='obsid' and a.value='oid080505'; + +which is significantly different than: + + SELECT * FROM "tmp_table2" WHERE name='obsid' and value='oid080505'; + +The user had adapted that query for her needs, but it would have been +better to just use the query that you suggested (as the subselect in +the DELETE FROM...). Unfortunately, that only improves performance +slightly - it is still way too slow on deletes. + +-- +Steve Wampler -- swampler@noao.edu +The gods that smiled on your birth are now laughing out loud. + +From pgsql-performance-owner@postgresql.org Tue Nov 15 04:28:35 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 71271D7E67 + for ; + Tue, 15 Nov 2005 04:28:34 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 93211-02 + for ; + Tue, 15 Nov 2005 08:28:34 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from zproxy.gmail.com (zproxy.gmail.com [64.233.162.196]) + by svr1.postgresql.org (Postfix) with ESMTP id 9EE35D6D8C + for ; + Tue, 15 Nov 2005 04:28:29 -0400 (AST) +Received: by zproxy.gmail.com with SMTP id m7so1901779nzf + for ; + Tue, 15 Nov 2005 00:28:30 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=UIKFEHWvVTKobTTlHA+0tXlOXSDmey1yoVjTjabopG3xDNXSJMB/ieRpw7X/IgepSIgVWXohYMA/ixFQ6/g82/OOs0i4f99OyXjy52yJYz2sXqyCCFkBaJ4jlPfdjVu+QHAbhagAfkL4yWnddWt5u4yi7HHdnYMMr4BfWFIAQnA= +Received: by 10.64.179.4 with SMTP id b4mr6457895qbf; + Tue, 15 Nov 2005 00:28:30 -0800 (PST) +Received: by 10.65.192.16 with HTTP; Tue, 15 Nov 2005 00:28:30 -0800 (PST) +Message-ID: +Date: Tue, 15 Nov 2005 09:28:30 +0100 +From: Claus Guttesen +To: Adam Weisberg +Subject: Re: Hardware/OS recommendations for large databases (5TB) +Cc: pgsql-performance@postgresql.org +In-Reply-To: <1B80C974ABFB23429A403B6667FE84C71066E8@seiumain.SEIU.local> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <1B80C974ABFB23429A403B6667FE84C71066E8@seiumain.SEIU.local> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/239 +X-Sequence-Number: 15496 + +> Does anyone have recommendations for hardware and/or OS to work with arou= +nd +> 5TB datasets? + +Hardware-wise I'd say dual core opterons. One dual-core-opteron +performs better than two single-core at the same speed. Tyan makes +some boards that have four sockets, thereby giving you 8 cpu's (if you +need that many). Sun and HP also makes nice hardware although the Tyan +board is more competetive priced. + +OS wise I would choose the FreeBSD amd64 port but partititions larger +than 2 TB needs some special care, using gpt rather than disklabel +etc., tools like fsck may not be able to completely check partitions +larger than 2 TB. Linux or Solaris with either LVM or Veritas FS +sounds like candidates. + +> I have been working with datasets no bigger than around 30GB, and that (I= +'m +> afraid to admit) has been in MSSQL. + +Well, our data are just below 30 GB so I can't help you there :-) + +regards +Claus + +From pgsql-performance-owner@postgresql.org Tue Nov 15 04:47:41 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 30770DB7E6 + for ; + Tue, 15 Nov 2005 04:47:40 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 94644-02 + for ; + Tue, 15 Nov 2005 08:47:40 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mx-2.sollentuna.net (mx-2.sollentuna.net [195.84.163.199]) + by svr1.postgresql.org (Postfix) with ESMTP id 4E448DB7C2 + for ; + Tue, 15 Nov 2005 04:47:36 -0400 (AST) +Received: from ALGOL.sollentuna.se (janus.sollentuna.se [62.65.68.67]) + by mx-2.sollentuna.net (Postfix) with ESMTP + id F21348F286; Tue, 15 Nov 2005 09:47:37 +0100 (CET) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Subject: Re: Help speeding up delete +Date: Tue, 15 Nov 2005 09:47:37 +0100 +Message-ID: <6BCB9D8A16AC4241919521715F4D8BCE6C7BC4@algol.sollentuna.se> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Help speeding up delete +thread-index: AcXpdueiGEYNxDEkTyGP+2rfwNG0fgASfQVA +From: "Magnus Hagander" +To: "Steve Wampler" , + "Scott Lamb" +Cc: "Postgres-performance" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/240 +X-Sequence-Number: 15497 + +> Because I think we need to. The above would only delete rows=20 +> that have name =3D 'obsid' and value =3D 'oid080505'. We need to=20 +> delete all rows that have the same ids as those rows. =20 +> However, from what you note, I bet we could do: +>=20 +> DELETE FROM "tmp_table2" WHERE id IN +> (SELECT id FROM "temp_table2" WHERE name =3D 'obsid' and=20 +> value=3D 'oid080505'); +>=20 +> However, even that seems to have a much higher cost than I'd expect: +>=20 +> lab.devel.configdb=3D# explain delete from "tmp_table2" where id in +> (select id from tmp_table2 where name=3D'obsid' and=20 +> value =3D 'oid080505'); +> NOTICE: QUERY PLAN: +>=20 +> Seq Scan on tmp_table2 (cost=3D0.00..65705177237.26=20 +> rows=3D769844 width=3D6) +> SubPlan +> -> Materialize (cost=3D42674.32..42674.32 rows=3D38 = +width=3D50) +> -> Seq Scan on tmp_table2 (cost=3D0.00..42674.32=20 +> rows=3D38 width=3D50) +>=20 +> EXPLAIN +>=20 +> And, sure enough, is taking an extrordinarily long time to=20 +> run (more than 10 minutes so far, compared to < 10seconds for=20 +> the select). Is this really typical of deletes? It appears=20 +> (to me) to be the Seq Scan on tmp_table2 that is the killer=20 +> here. If we put an index on, would it help? (The user=20 +> claims she tried that and it's EXPLAIN cost went even higher,=20 +> but I haven't checked that...) + + +Earlier pg versions have always been bad at dealing with IN subqueries. +Try rewriting it as (with fixing any broken syntax, I'm not actually +testing this :P) + +DELETE FROM tmp_table2 WHERE EXISTS=20 + (SELECT * FROM tmp_table2 t2 WHERE t2.id=3Dtmp_table2.id AND +t2.name=3D'obsid' AND t2.value=3D'oid080505') + + +I assume you do have an index on tmp_table2.id :-) And that it's +non-unique? (If it was unique, the previous simplification of the query +really should've worked..) + +Do you also have an index on "name,value" or something like that, so you +get an index scan from it? + +//Magnus + +From pgsql-performance-owner@postgresql.org Fri Nov 18 16:43:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id BAE07DA2EF + for ; + Tue, 15 Nov 2005 06:06:37 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 10049-08 + for ; + Tue, 15 Nov 2005 10:06:38 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id EDDC4D6D8C + for ; + Tue, 15 Nov 2005 06:06:33 -0400 (AST) +Received: from hotmail.com (bay103-f11.bay103.hotmail.com [65.54.174.21]) + by svr2.postgresql.org (Postfix) with ESMTP id 15931F10B2 + for ; + Tue, 15 Nov 2005 10:06:35 +0000 (GMT) +Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; + Tue, 15 Nov 2005 02:06:33 -0800 +Message-ID: +Received: from 65.54.174.200 by by103fd.bay103.hotmail.msn.com with HTTP; + Tue, 15 Nov 2005 10:06:33 GMT +X-Originating-IP: [64.60.124.12] +X-Originating-Email: [v_saks@hotmail.com] +X-Sender: v_saks@hotmail.com +From: "Virag Saksena" +To: pgsql-performance@postgresql.org +Subject: ERROR: no value found for parameter 1 with JDBC and Explain Analyze +Date: Tue, 15 Nov 2005 10:06:33 +0000 +Mime-Version: 1.0 +Content-Type: text/plain; format=flowed +X-OriginalArrivalTime: 15 Nov 2005 10:06:33.0362 (UTC) + FILETIME=[41A15720:01C5E9CC] +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.919 required=5 tests=[DNS_FROM_RFC_ABUSE=0.479, + DNS_FROM_RFC_POST=1.44, MSGID_FROM_MTA_HEADER=0] +X-Spam-Score: 1.919 +X-Spam-Level: * +X-Archive-Number: 200511/383 +X-Sequence-Number: 15640 + +Hi, +I am trying to use Explain Analyze to trace a slow SQL statement called from +JDBC. +The SQL statement with the parameters taked 11 seconds. When I run a explain +analyze from psql, it takes < 50 ms with a reasonable explain plan. However +when I try to run an explain analyze from JDBC with the parameters, I get +error : +ERROR: no value found for parameter 1 + +Here is sample code which causes this exception ... + pst=prodconn.prepareStatement("explain analyze select count(*) from +jam_heaprel r where heap_id = ? and parentaddr = ?"); + pst.setInt(1,1); + pst.setInt(2,0); + rs=pst.executeQuery(); + +java.sql.SQLException: ERROR: no value found for parameter 1 + at +org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:1471) + at +org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1256) + at +org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:175) + at +org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:389) + at +org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:330) + at +org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:240) + at jsp._testexplain_2ejsp._jspService(_testexplain_2ejsp.java:82) + at org.gjt.jsp.HttpJspPageImpl.service(HttpJspPageImpl.java:75) + +Regards, + +Virag + + + +From pgsql-performance-owner@postgresql.org Tue Nov 15 08:10:50 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id C28BCDB811 + for ; + Tue, 15 Nov 2005 08:10:47 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 23088-02 + for ; + Tue, 15 Nov 2005 12:10:49 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw03.mi8.com [63.240.6.42]) + by svr1.postgresql.org (Postfix) with ESMTP id 6047CDB82F + for ; + Tue, 15 Nov 2005 08:10:44 -0400 (AST) +Received: from 172.16.1.112 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D3)); Tue, 15 Nov 2005 07:10:37 -0500 +X-Server-Uuid: E847189C-FC88-4913-9CD4-DE66914F83C0 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Tue, 15 Nov + 2005 07:10:19 -0500 +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Tue, 15 Nov 2005 07:09:56 -0500 +Message-ID: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases ( 5TB) +Thread-Index: AcXpwCbNgx8G/OwDQbe+GZ855Fd0GQAHJV/A +From: "Luke Lonergan" +To: "Adam Weisberg" +cc: pgsql-performance@postgresql.org +X-OriginalArrivalTime: 15 Nov 2005 12:10:19.0047 (UTC) + FILETIME=[8BAEF370:01C5E9DD] +X-WSS-ID: 6F670FB72BW8755554-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: quoted-printable +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/241 +X-Sequence-Number: 15498 + +Adam, + +> -----Original Message----- +> From: pgsql-performance-owner@postgresql.org=20 +> [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of=20 +> Claus Guttesen +> Sent: Tuesday, November 15, 2005 12:29 AM +> To: Adam Weisberg +> Cc: pgsql-performance@postgresql.org +> Subject: Re: [PERFORM] Hardware/OS recommendations for large=20 +> databases ( 5TB) +>=20 +> > Does anyone have recommendations for hardware and/or OS to=20 +> work with=20 +> > around 5TB datasets? +>=20 +> Hardware-wise I'd say dual core opterons. One=20 +> dual-core-opteron performs better than two single-core at the=20 +> same speed. Tyan makes some boards that have four sockets,=20 +> thereby giving you 8 cpu's (if you need that many). Sun and=20 +> HP also makes nice hardware although the Tyan board is more=20 +> competetive priced. +>=20 +> OS wise I would choose the FreeBSD amd64 port but=20 +> partititions larger than 2 TB needs some special care, using=20 +> gpt rather than disklabel etc., tools like fsck may not be=20 +> able to completely check partitions larger than 2 TB. Linux=20 +> or Solaris with either LVM or Veritas FS sounds like candidates. + +I agree - you can get a very good one from www.acmemicro.com or +www.rackable.com with 8x 400GB SATA disks and the new 3Ware 9550SX SATA +RAID controller for about $6K with two Opteron 272 CPUs and 8GB of RAM +on a Tyan 2882 motherboard. We get about 400MB/s sustained disk read +performance on these (with tuning) on Linux using the xfs filesystem, +which is one of the most critical factors for large databases. =20 + +Note that you want to have your DBMS use all of the CPU and disk channel +bandwidth you have on each query, which takes a parallel database like +Bizgres MPP to achieve. + +Regards, + +- Luke + + +From pgsql-performance-owner@postgresql.org Tue Nov 15 10:09:23 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 2C35EDB847 + for ; + Tue, 15 Nov 2005 10:09:22 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 33686-06 + for ; + Tue, 15 Nov 2005 14:09:24 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (c-24-11-237-16.hsd1.mi.comcast.net + [24.11.237.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 7F332DB7EB + for ; + Tue, 15 Nov 2005 10:09:17 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Hardware/OS recommendations for large databases (5TB) +Date: Tue, 15 Nov 2005 09:09:21 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD892@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases (5TB) +Thread-Index: AcXpvzV5hVFHPWZkSgW5F5EVOZa9hQALkdOw +From: "Merlin Moncure" +To: "Claus Guttesen" +Cc: , + "Adam Weisberg" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.988 required=5 tests=[RCVD_IN_SORBS_DUL=1.988] +X-Spam-Score: 1.988 +X-Spam-Level: * +X-Archive-Number: 200511/242 +X-Sequence-Number: 15499 + +> Hardware-wise I'd say dual core opterons. One dual-core-opteron +> performs better than two single-core at the same speed. Tyan makes +> some boards that have four sockets, thereby giving you 8 cpu's (if you +> need that many). Sun and HP also makes nice hardware although the Tyan +> board is more competetive priced. + +just FYI: tyan makes a 8 socket motherboard (up to 16 cores!): +http://www.swt.com/vx50.html + +It can be loaded with up to 128 gb memory if all the sockets are filled +:). + +Merlin + +From pgsql-performance-owner@postgresql.org Tue Nov 15 10:18:25 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5E995DB807 + for ; + Tue, 15 Nov 2005 10:18:24 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 36252-04 + for ; + Tue, 15 Nov 2005 14:18:26 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from net2.micro-automation.com (net2.micro-automation.com + [64.7.141.29]) + by svr1.postgresql.org (Postfix) with SMTP id 74324DB7EB + for ; + Tue, 15 Nov 2005 10:18:20 -0400 (AST) +Received: (qmail 12139 invoked from network); 15 Nov 2005 14:18:24 -0000 +Received: from dcdsl.ebox.com (HELO ?192.168.1.2?) (davec@64.7.143.116) + by net2.micro-automation.com with SMTP; 15 Nov 2005 14:18:24 -0000 +In-Reply-To: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: multipart/alternative; boundary=Apple-Mail-26--861917900 +Message-Id: +Cc: "Adam Weisberg" , pgsql-performance@postgresql.org +From: Dave Cramer +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Tue, 15 Nov 2005 09:15:04 -0500 +To: Luke Lonergan +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[HTML_MESSAGE=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/244 +X-Sequence-Number: 15501 + + +--Apple-Mail-26--861917900 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; + charset=US-ASCII; + delsp=yes; + format=flowed + +Luke, + +Have you tried the areca cards, they are slightly faster yet. + +Dave +On 15-Nov-05, at 7:09 AM, Luke Lonergan wrote: + +> +> I agree - you can get a very good one from www.acmemicro.com or +> www.rackable.com with 8x 400GB SATA disks and the new 3Ware 9550SX +> SATA +> RAID controller for about $6K with two Opteron 272 CPUs and 8GB of RAM +> on a Tyan 2882 motherboard. We get about 400MB/s sustained disk read +> performance on these (with tuning) on Linux using the xfs filesystem, +> which is one of the most critical factors for large databases. +> +> Note that you want to have your DBMS use all of the CPU and disk +> channel +> bandwidth you have on each query, which takes a parallel database like +> Bizgres MPP to achieve. +> +> Regards, + + +--Apple-Mail-26--861917900 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/html; + charset=ISO-8859-1 + +Luke,

Have you tried the areca = +cards, they are slightly faster yet.

Dave
On = +15-Nov-05, at 7:09 AM, Luke Lonergan wrote:


I agree - you can get a very good one from www.acmemicro.com or

www.rackable.com with 8x 400GB SATA = +disks and the new 3Ware 9550SX SATA

RAID controller for about $6K with two Opteron 272 = +CPUs and 8GB of RAM

on a Tyan 2882 motherboard.=A0 We get about 400MB/s = +sustained disk read

performance on these (with tuning) on Linux using the xfs = +filesystem,

which is one of the most critical factors for large = +databases. =A0

= +


Note that you want to have your DBMS use all of the CPU and = +disk channel

bandwidth you have on each query, which takes a parallel = +database like

Bizgres MPP to achieve.


= +

Regards,

= +

= + +--Apple-Mail-26--861917900-- + +From pgsql-performance-owner@postgresql.org Tue Nov 15 10:18:19 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 86BD0DB73B + for ; + Tue, 15 Nov 2005 10:18:18 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 36540-02 + for ; + Tue, 15 Nov 2005 14:18:20 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from noao.edu (noao.edu [140.252.1.54]) + by svr1.postgresql.org (Postfix) with ESMTP id 1FACBDACDE + for ; + Tue, 15 Nov 2005 10:18:14 -0400 (AST) +X-TFF-CGPSA-Version: 1.4f1 +X-TFF-CGPSA-Filter: Scanned +Received: from weaver.tuc.noao.edu ([140.252.14.8] verified) + by noao.edu (CommuniGate Pro SMTP 5.0.1) + with ESMTPS id 21646979; Tue, 15 Nov 2005 07:18:13 -0700 +Received: from [127.0.0.1] (localhost.localdomain [127.0.0.1]) + by weaver.tuc.noao.edu (8.13.1/8.13.1) with ESMTP id jAFEICVY022915; + Tue, 15 Nov 2005 07:18:12 -0700 +Message-ID: <4379EE24.8000504@noao.edu> +Date: Tue, 15 Nov 2005 07:18:12 -0700 +From: Steve Wampler +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Magnus Hagander +CC: Postgres-performance +Subject: Re: Help speeding up delete +References: <6BCB9D8A16AC4241919521715F4D8BCE6C7BC4@algol.sollentuna.se> +In-Reply-To: <6BCB9D8A16AC4241919521715F4D8BCE6C7BC4@algol.sollentuna.se> +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/243 +X-Sequence-Number: 15500 + +Magnus Hagander wrote: +>>Because I think we need to. The above would only delete rows +>>that have name = 'obsid' and value = 'oid080505'. We need to +>>delete all rows that have the same ids as those rows. +>>However, from what you note, I bet we could do: +>> +>> DELETE FROM "tmp_table2" WHERE id IN +>> (SELECT id FROM "temp_table2" WHERE name = 'obsid' and +>>value= 'oid080505'); +>> +>>However, even that seems to have a much higher cost than I'd expect: +>> +>> lab.devel.configdb=# explain delete from "tmp_table2" where id in +>> (select id from tmp_table2 where name='obsid' and +>>value = 'oid080505'); +>> NOTICE: QUERY PLAN: +>> +>> Seq Scan on tmp_table2 (cost=0.00..65705177237.26 +>>rows=769844 width=6) +>> SubPlan +>> -> Materialize (cost=42674.32..42674.32 rows=38 width=50) +>> -> Seq Scan on tmp_table2 (cost=0.00..42674.32 +>>rows=38 width=50) +>> +>> EXPLAIN +... +> +> Earlier pg versions have always been bad at dealing with IN subqueries. +> Try rewriting it as (with fixing any broken syntax, I'm not actually +> testing this :P) +> +> DELETE FROM tmp_table2 WHERE EXISTS +> (SELECT * FROM tmp_table2 t2 WHERE t2.id=tmp_table2.id AND +> t2.name='obsid' AND t2.value='oid080505') + +Thanks - that looks *significantly* better: + + lab.devel.configdb=# explain delete from tmp_table2 where exists + (select 1 from tmp_table2 t2 where + t2.id=tmp_table2.id and + t2.name='obsid' and t2.value='oid080505'); + NOTICE: QUERY PLAN: + + Seq Scan on tmp_table2 (cost=0.00..9297614.80 rows=769844 width=6) + SubPlan + -> Index Scan using inv_index_2 on tmp_table2 t2 (cost=0.00..6.02 rows=1 width=0) + + EXPLAIN + +(This is after putting an index on the (id,name,value) tuple.) That outer seq scan +is still annoying, but maybe this will be fast enough. + +I've passed this on, along with the (strong) recommendation that they +upgrade PG. + +Thanks!! + +-- +Steve Wampler -- swampler@noao.edu +The gods that smiled on your birth are now laughing out loud. + +From pgsql-performance-owner@postgresql.org Tue Nov 15 10:34:17 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CA28CD6D8C + for ; + Tue, 15 Nov 2005 10:34:15 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 37600-03 + for ; + Tue, 15 Nov 2005 14:34:18 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id C9F7BDB82E + for ; + Tue, 15 Nov 2005 10:34:11 -0400 (AST) +Received: from 172.16.1.112 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Tue, 15 Nov 2005 09:34:00 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Tue, 15 Nov + 2005 09:33:48 -0500 +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Tue, 15 Nov 2005 09:33:25 -0500 +Message-ID: <3E37B936B592014B978C4415F90D662D01995FD4@MI8NYCMAIL06.Mi8.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXp8MdsVv42c8bqS3ONBiM5ZKGehwAADrlg +From: "Luke Lonergan" +To: "Dave Cramer" +cc: "Adam Weisberg" , pgsql-performance@postgresql.org +X-OriginalArrivalTime: 15 Nov 2005 14:33:48.0648 (UTC) + FILETIME=[9767CE80:01C5E9F1] +X-WSS-ID: 6F672E5C31S11414546-23-01 +Content-Type: multipart/alternative; + boundary="----_=_NextPart_001_01C5E9F1.9708CA4B" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[AWL=-0.001, + HTML_MESSAGE=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/245 +X-Sequence-Number: 15502 + +This is a multi-part message in MIME format. + +------_=_NextPart_001_01C5E9F1.9708CA4B +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: quoted-printable + +Dave, + + +________________________________ + + From: pgsql-performance-owner@postgresql.org +[mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Dave Cramer + Sent: Tuesday, November 15, 2005 6:15 AM + To: Luke Lonergan + Cc: Adam Weisberg; pgsql-performance@postgresql.org + Subject: Re: [PERFORM] Hardware/OS recommendations for large +databases ( +=09 +=09 + Luke,=20 +=09 +=09 + Have you tried the areca cards, they are slightly faster yet.=20 + +No, I've been curious since I read an earlier posting here. I've had a +lot more experience with the 3Ware cards, mostly good, and they've been +doing a lot of volume with Rackable/Yahoo which gives me some more +confidence. +=20 +The new 3Ware 9550SX cards use a PowerPC for checksumming, so their +write performance is now up to par with the best cards I believe. We +find that you still need to set Linux readahead to at least 8MB +(blockdev --setra) to get maximum read performance on them, is that your +experience with the Arecas? We get about 260MB/s read on 8 drives in +RAID5 without the readahead tuning and about 400MB/s with it. +=20 +- Luke + +------_=_NextPart_001_01C5E9F1.9708CA4B +Content-Type: text/html; + charset=us-ascii +Content-Transfer-Encoding: quoted-printable + + + + + + +
Dave,

+
+
+
+ From: = +pgsql-performance-owner@postgresql.org=20 + [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of = +Dave=20 + Cramer
Sent: Tuesday, November 15, 2005 6:15 = +AM
To: Luke=20 + Lonergan
Cc: Adam Weisberg;=20 + pgsql-performance@postgresql.org
Subject: Re: [PERFORM] = +Hardware/OS=20 + recommendations for large databases (

+
Luke, +
+
Have you tried the areca cards, they are slightly faster = +yet. 
+
No, I've been curious since I read an earlier posting = +here.  I've=20 +had a lot more experience with the 3Ware cards, mostly good, and they've = +been=20 +doing a lot of volume with Rackable/Yahoo which gives=20 +me some more confidence.
+
 
+
The new 3Ware 9550SX cards use a PowerPC for checksumming, so = +their write=20 +performance is now up to par with the best cards I believe.  We = +find that=20 +you still need to set Linux readahead to at least 8MB (blockdev --setra) = +to get=20 +maximum read performance on them, is that your experience with the = +Arecas? =20 +We get about 260MB/s read on 8 drives in RAID5 without the readahead = +tuning and=20 +about 400MB/s with it.
+
 
+
- Luke
+ +------_=_NextPart_001_01C5E9F1.9708CA4B-- + + +From pgsql-performance-owner@postgresql.org Tue Nov 15 10:37:48 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 18312DB807 + for ; + Tue, 15 Nov 2005 10:37:47 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 38296-04 + for ; + Tue, 15 Nov 2005 14:37:47 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw03.mi8.com [63.240.6.42]) + by svr1.postgresql.org (Postfix) with ESMTP id ED20CDB802 + for ; + Tue, 15 Nov 2005 10:37:41 -0400 (AST) +Received: from 172.16.1.110 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D3)); Tue, 15 Nov 2005 09:37:33 -0500 +X-Server-Uuid: E847189C-FC88-4913-9CD4-DE66914F83C0 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Tue, 15 Nov + 2005 09:36:44 -0500 +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Tue, 15 Nov 2005 09:36:21 -0500 +Message-ID: <3E37B936B592014B978C4415F90D662D01995FDD@MI8NYCMAIL06.Mi8.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases ( 5TB) +Thread-Index: AcXpvzV5hVFHPWZkSgW5F5EVOZa9hQALkdOwAAEU6wA= +From: "Luke Lonergan" +To: "Merlin Moncure" , + "Claus Guttesen" +cc: pgsql-performance@postgresql.org, "Adam Weisberg" +X-OriginalArrivalTime: 15 Nov 2005 14:36:44.0382 (UTC) + FILETIME=[0026AFE0:01C5E9F2] +X-WSS-ID: 6F672D272BW8850313-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: quoted-printable +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/246 +X-Sequence-Number: 15503 + +Merlin,=20 + +> just FYI: tyan makes a 8 socket motherboard (up to 16 cores!): +> http://www.swt.com/vx50.html +>=20 +> It can be loaded with up to 128 gb memory if all the sockets=20 +> are filled :). + +Cool! + +Just remember that you can't get more than 1 CPU working on a query at a +time without a parallel database. + +- Luke + + +From pgsql-performance-owner@postgresql.org Tue Nov 15 10:50:34 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 28ECBDB7EB + for ; + Tue, 15 Nov 2005 10:50:34 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 38135-08 + for ; + Tue, 15 Nov 2005 14:50:36 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw02.mi8.com [63.240.6.46]) + by svr1.postgresql.org (Postfix) with ESMTP id 6BD90DB7B3 + for ; + Tue, 15 Nov 2005 10:50:30 -0400 (AST) +Received: from 172.16.1.110 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D2)); Tue, 15 Nov 2005 09:50:26 -0500 +X-Server-Uuid: 7829E76E-BB9E-4995-8473-3C0929DF7DD1 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Tue, 15 Nov + 2005 09:49:48 -0500 +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Tue, 15 Nov 2005 09:49:26 -0500 +Message-ID: <3E37B936B592014B978C4415F90D662D01995FF5@MI8NYCMAIL06.Mi8.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases ( 5TB) +Thread-Index: AcXpvzV5hVFHPWZkSgW5F5EVOZa9hQALkdOwAAEU6wAAACrUAA== +From: "Luke Lonergan" +To: "Merlin Moncure" , + "Claus Guttesen" +cc: pgsql-performance@postgresql.org, "Adam Weisberg" +X-OriginalArrivalTime: 15 Nov 2005 14:49:48.0871 (UTC) + FILETIME=[D3BE3570:01C5E9F3] +X-WSS-ID: 6F672A3B2RS6765630-06-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: quoted-printable +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/247 +X-Sequence-Number: 15504 + +Merlin, + +> > just FYI: tyan makes a 8 socket motherboard (up to 16 cores!): +> > http://www.swt.com/vx50.html +> >=20 +> > It can be loaded with up to 128 gb memory if all the sockets are=20 +> > filled :). + +Another thought - I priced out a maxed out machine with 16 cores and +128GB of RAM and 1.5TB of usable disk - $71,000. + +You could instead buy 8 machines that total 16 cores, 128GB RAM and 28TB +of disk for $48,000, and it would be 16 times faster in scan rate, which +is the most important factor for large databases. The size would be 16 +rack units instead of 5, and you'd have to add a GigE switch for $1500. + +Scan rate for above SMP: 200MB/s + +Scan rate for above cluster: 3,200Mb/s + +You could even go dual core and double the memory on the cluster and +you'd about match the price of the "god box". + +- Luke + + +From pgsql-performance-owner@postgresql.org Tue Nov 15 10:55:47 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 26280DB7B3 + for ; + Tue, 15 Nov 2005 10:55:46 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 38857-10 + for ; + Tue, 15 Nov 2005 14:55:48 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from vms040pub.verizon.net (vms040pub.verizon.net [206.46.252.40]) + by svr1.postgresql.org (Postfix) with ESMTP id BE4E1DB6AA + for ; + Tue, 15 Nov 2005 10:55:42 -0400 (AST) +Received: from osgiliath.mathom.us ([70.108.64.202]) + by vms040.mailsrvcs.net (Sun Java System Messaging Server 6.2-4.02 + (built Sep + 9 2005)) with ESMTPA id <0IQ000CK444YHVND@vms040.mailsrvcs.net> for + pgsql-performance@postgresql.org; Tue, 15 Nov 2005 08:55:46 -0600 (CST) +Received: from localhost (localhost [127.0.0.1]) + by osgiliath.mathom.us (Postfix) with ESMTP id D038C607898; Tue, + 15 Nov 2005 09:55:45 -0500 (EST) +Received: from osgiliath.mathom.us ([127.0.0.1]) + by localhost (osgiliath [127.0.0.1]) (amavisd-new, port 10024) + with LMTP id 04523-02-5; Tue, 15 Nov 2005 09:55:45 -0500 (EST) +Received: by osgiliath.mathom.us (Postfix, from userid 1000) + id B20576063FF; Tue, 15 Nov 2005 09:55:45 -0500 (EST) +Date: Tue, 15 Nov 2005 09:55:45 -0500 +From: Michael Stone +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <3E37B936B592014B978C4415F90D662D01995FD4@MI8NYCMAIL06.Mi8.com> +To: Luke Lonergan +Cc: pgsql-performance@postgresql.org +Mail-followup-to: Luke Lonergan , + pgsql-performance@postgresql.org +Message-id: <20051115145545.GQ9905@mathom.us> +MIME-version: 1.0 +Content-type: text/plain; charset=us-ascii; format=flowed +Content-disposition: inline +X-Pgp-Fingerprint: 53 FF 38 00 E7 DD 0A 9C 84 52 84 C5 EE DF 7C 88 +X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at mathom.us +References: <3E37B936B592014B978C4415F90D662D01995FD4@MI8NYCMAIL06.Mi8.com> +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/248 +X-Sequence-Number: 15505 + +On Tue, Nov 15, 2005 at 09:33:25AM -0500, Luke Lonergan wrote: +>write performance is now up to par with the best cards I believe. We +>find that you still need to set Linux readahead to at least 8MB +>(blockdev --setra) to get maximum read performance on them, is that your + +What on earth does that do to your seek performance? + +Mike Stone + +From pgsql-performance-owner@postgresql.org Tue Nov 15 11:20:06 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9E18BDB83A + for ; + Tue, 15 Nov 2005 11:20:05 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 43545-01 + for ; + Tue, 15 Nov 2005 15:20:08 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (c-24-11-237-16.hsd1.mi.comcast.net + [24.11.237.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 2CD18DB817 + for ; + Tue, 15 Nov 2005 11:20:01 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Hardware/OS recommendations for large databases ( 5TB) +Date: Tue, 15 Nov 2005 10:20:05 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD898@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases ( 5TB) +Thread-Index: AcXpvzV5hVFHPWZkSgW5F5EVOZa9hQALkdOwAAEU6wAAACrUAAABI4TA +From: "Merlin Moncure" +To: "Luke Lonergan" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.657 required=5 tests=[AWL=-0.331, + RCVD_IN_SORBS_DUL=1.988] +X-Spam-Score: 1.657 +X-Spam-Level: * +X-Archive-Number: 200511/249 +X-Sequence-Number: 15506 + +> Merlin, +>=20 +> > > just FYI: tyan makes a 8 socket motherboard (up to 16 cores!): +> > > http://www.swt.com/vx50.html +> > > +> > > It can be loaded with up to 128 gb memory if all the sockets are +> > > filled :). +>=20 +> Another thought - I priced out a maxed out machine with 16 cores and +> 128GB of RAM and 1.5TB of usable disk - $71,000. +>=20 +> You could instead buy 8 machines that total 16 cores, 128GB RAM and +28TB +> of disk for $48,000, and it would be 16 times faster in scan rate, +which +> is the most important factor for large databases. The size would be +16 +> rack units instead of 5, and you'd have to add a GigE switch for +$1500. +=20 +It's hard to say what would be better. My gut says the 5u box would be +a lot better at handling high cpu/high concurrency problems...like your +typical business erp backend. This is pure speculation of course...I'll +defer to the experts here. + +Merlin + + +From pgsql-performance-owner@postgresql.org Tue Nov 15 11:40:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id ADF35DB7C2 + for ; + Tue, 15 Nov 2005 11:40:44 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 44429-06 + for ; + Tue, 15 Nov 2005 15:40:47 +0000 (GMT) +X-Greylist: delayed 15:54:07.940321 by SQLgrey- +Received: from seiumain.SEIU.local (unknown [204.107.254.246]) + by svr1.postgresql.org (Postfix) with ESMTP id E8744DB7B3 + for ; + Tue, 15 Nov 2005 11:40:40 -0400 (AST) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Hardware/OS recommendations for large databases ( 5TB) +X-MimeOLE: Produced By Microsoft Exchange V6.5 +Date: Tue, 15 Nov 2005 10:40:53 -0500 +Message-ID: <1B80C974ABFB23429A403B6667FE84C71066E9@seiumain.SEIU.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases ( 5TB) +Thread-Index: AcXpwCbNgx8G/OwDQbe+GZ855Fd0GQAHJV/AAAcvS2A= +From: "Adam Weisberg" +To: "Luke Lonergan" +Cc: +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/250 +X-Sequence-Number: 15507 + +Luke, + +-----Original Message----- +From: Luke Lonergan [mailto:LLonergan@greenplum.com]=20 +Sent: Tuesday, November 15, 2005 7:10 AM +To: Adam Weisberg +Cc: pgsql-performance@postgresql.org +Subject: RE: [PERFORM] Hardware/OS recommendations for large databases ( +5TB) + +Adam, + +> -----Original Message----- +> From: pgsql-performance-owner@postgresql.org +> [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Claus=20 +> Guttesen +> Sent: Tuesday, November 15, 2005 12:29 AM +> To: Adam Weisberg +> Cc: pgsql-performance@postgresql.org +> Subject: Re: [PERFORM] Hardware/OS recommendations for large databases + +> ( 5TB) +>=20 +> > Does anyone have recommendations for hardware and/or OS to +> work with +> > around 5TB datasets? +>=20 +> Hardware-wise I'd say dual core opterons. One dual-core-opteron=20 +> performs better than two single-core at the same speed. Tyan makes=20 +> some boards that have four sockets, thereby giving you 8 cpu's (if you + +> need that many). Sun and HP also makes nice hardware although the Tyan + +> board is more competetive priced. +>=20 +> OS wise I would choose the FreeBSD amd64 port but partititions larger=20 +> than 2 TB needs some special care, using gpt rather than disklabel=20 +> etc., tools like fsck may not be able to completely check partitions=20 +> larger than 2 TB. Linux or Solaris with either LVM or Veritas FS=20 +> sounds like candidates. + +I agree - you can get a very good one from www.acmemicro.com or +www.rackable.com with 8x 400GB SATA disks and the new 3Ware 9550SX SATA +RAID controller for about $6K with two Opteron 272 CPUs and 8GB of RAM +on a Tyan 2882 motherboard. We get about 400MB/s sustained disk read +performance on these (with tuning) on Linux using the xfs filesystem, +which is one of the most critical factors for large databases. =20 + +Note that you want to have your DBMS use all of the CPU and disk channel +bandwidth you have on each query, which takes a parallel database like +Bizgres MPP to achieve. + +Regards, + +- Luke + + +The What's New FAQ for PostgreSQL 8.1 says "the buffer manager for 8.1 +has been enhanced to scale almost linearly with the number of +processors, leading to significant performance gains on 8-way, 16-way, +dual-core, and multi-core CPU servers." + +Why not just use it as-is? + +Cheers, + +Adam + +From pgsql-performance-owner@postgresql.org Tue Nov 15 11:51:07 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A01BBDAAAA + for ; + Tue, 15 Nov 2005 11:51:06 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 45563-07 + for ; + Tue, 15 Nov 2005 15:51:09 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id AE415DA361 + for ; + Tue, 15 Nov 2005 11:51:02 -0400 (AST) +Received: from 172.16.1.112 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Tue, 15 Nov 2005 10:51:02 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Tue, 15 Nov + 2005 10:50:51 -0500 +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Tue, 15 Nov 2005 10:50:49 -0500 +Message-ID: <3E37B936B592014B978C4415F90D662DE11DD7@MI8NYCMAIL06.Mi8.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases ( 5TB) +Thread-Index: AcXpwCbNgx8G/OwDQbe+GZ855Fd0GQAHJV/AAAcvS2AAALfzHg== +From: "Luke Lonergan" +To: Aweisberg@seiu1199.org +cc: pgsql-performance@postgresql.org +X-OriginalArrivalTime: 15 Nov 2005 15:50:51.0215 (UTC) + FILETIME=[5AAB8DF0:01C5E9FC] +X-WSS-ID: 6F64DC6E31S11480215-12-01 +Content-Type: text/plain; + charset=utf-8 +Content-Transfer-Encoding: base64 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/251 +X-Sequence-Number: 15508 + +QmVjYXVzZSBvbmx5IDEgY3B1IGlzIHVzZWQgb24gZWFjaCBxdWVyeS4NCi0gTHVrZQ0KLS0tLS0t +LS0tLS0tLS0tLS0tLS0tLS0tLS0NClNlbnQgZnJvbSBteSBCbGFja0JlcnJ5IFdpcmVsZXNzIERl +dmljZQ0KDQoNCi0tLS0tT3JpZ2luYWwgTWVzc2FnZS0tLS0tDQpGcm9tOiBBZGFtIFdlaXNiZXJn +IDxBd2Vpc2JlcmdAc2VpdTExOTkub3JnPg0KVG86IEx1a2UgTG9uZXJnYW4gPExMb25lcmdhbkBn +cmVlbnBsdW0uY29tPg0KQ0M6IHBnc3FsLXBlcmZvcm1hbmNlQHBvc3RncmVzcWwub3JnIDxwZ3Nx +bC1wZXJmb3JtYW5jZUBwb3N0Z3Jlc3FsLm9yZz4NClNlbnQ6IFR1ZSBOb3YgMTUgMTA6NDA6NTMg +MjAwNQ0KU3ViamVjdDogUkU6IFtQRVJGT1JNXSBIYXJkd2FyZS9PUyByZWNvbW1lbmRhdGlvbnMg +Zm9yIGxhcmdlIGRhdGFiYXNlcyAoIDVUQikNCg0KTHVrZSwNCg0KLS0tLS1PcmlnaW5hbCBNZXNz +YWdlLS0tLS0NCkZyb206IEx1a2UgTG9uZXJnYW4gW21haWx0bzpMTG9uZXJnYW5AZ3JlZW5wbHVt +LmNvbV0gDQpTZW50OiBUdWVzZGF5LCBOb3ZlbWJlciAxNSwgMjAwNSA3OjEwIEFNDQpUbzogQWRh +bSBXZWlzYmVyZw0KQ2M6IHBnc3FsLXBlcmZvcm1hbmNlQHBvc3RncmVzcWwub3JnDQpTdWJqZWN0 +OiBSRTogW1BFUkZPUk1dIEhhcmR3YXJlL09TIHJlY29tbWVuZGF0aW9ucyBmb3IgbGFyZ2UgZGF0 +YWJhc2VzICgNCjVUQikNCg0KQWRhbSwNCg0KPiAtLS0tLU9yaWdpbmFsIE1lc3NhZ2UtLS0tLQ0K +PiBGcm9tOiBwZ3NxbC1wZXJmb3JtYW5jZS1vd25lckBwb3N0Z3Jlc3FsLm9yZw0KPiBbbWFpbHRv +OnBnc3FsLXBlcmZvcm1hbmNlLW93bmVyQHBvc3RncmVzcWwub3JnXSBPbiBCZWhhbGYgT2YgQ2xh +dXMgDQo+IEd1dHRlc2VuDQo+IFNlbnQ6IFR1ZXNkYXksIE5vdmVtYmVyIDE1LCAyMDA1IDEyOjI5 +IEFNDQo+IFRvOiBBZGFtIFdlaXNiZXJnDQo+IENjOiBwZ3NxbC1wZXJmb3JtYW5jZUBwb3N0Z3Jl +c3FsLm9yZw0KPiBTdWJqZWN0OiBSZTogW1BFUkZPUk1dIEhhcmR3YXJlL09TIHJlY29tbWVuZGF0 +aW9ucyBmb3IgbGFyZ2UgZGF0YWJhc2VzDQoNCj4gKCA1VEIpDQo+IA0KPiA+IERvZXMgYW55b25l +IGhhdmUgcmVjb21tZW5kYXRpb25zIGZvciBoYXJkd2FyZSBhbmQvb3IgT1MgdG8NCj4gd29yayB3 +aXRoDQo+ID4gYXJvdW5kIDVUQiBkYXRhc2V0cz8NCj4gDQo+IEhhcmR3YXJlLXdpc2UgSSdkIHNh +eSBkdWFsIGNvcmUgb3B0ZXJvbnMuIE9uZSBkdWFsLWNvcmUtb3B0ZXJvbiANCj4gcGVyZm9ybXMg +YmV0dGVyIHRoYW4gdHdvIHNpbmdsZS1jb3JlIGF0IHRoZSBzYW1lIHNwZWVkLiBUeWFuIG1ha2Vz +IA0KPiBzb21lIGJvYXJkcyB0aGF0IGhhdmUgZm91ciBzb2NrZXRzLCB0aGVyZWJ5IGdpdmluZyB5 +b3UgOCBjcHUncyAoaWYgeW91DQoNCj4gbmVlZCB0aGF0IG1hbnkpLiBTdW4gYW5kIEhQIGFsc28g +bWFrZXMgbmljZSBoYXJkd2FyZSBhbHRob3VnaCB0aGUgVHlhbg0KDQo+IGJvYXJkIGlzIG1vcmUg +Y29tcGV0ZXRpdmUgcHJpY2VkLg0KPiANCj4gT1Mgd2lzZSBJIHdvdWxkIGNob29zZSB0aGUgRnJl +ZUJTRCBhbWQ2NCBwb3J0IGJ1dCBwYXJ0aXRpdGlvbnMgbGFyZ2VyIA0KPiB0aGFuIDIgVEIgbmVl +ZHMgc29tZSBzcGVjaWFsIGNhcmUsIHVzaW5nIGdwdCByYXRoZXIgdGhhbiBkaXNrbGFiZWwgDQo+ +IGV0Yy4sIHRvb2xzIGxpa2UgZnNjayBtYXkgbm90IGJlIGFibGUgdG8gY29tcGxldGVseSBjaGVj +ayBwYXJ0aXRpb25zIA0KPiBsYXJnZXIgdGhhbiAyIFRCLiBMaW51eCBvciBTb2xhcmlzIHdpdGgg +ZWl0aGVyIExWTSBvciBWZXJpdGFzIEZTIA0KPiBzb3VuZHMgbGlrZSBjYW5kaWRhdGVzLg0KDQpJ +IGFncmVlIC0geW91IGNhbiBnZXQgYSB2ZXJ5IGdvb2Qgb25lIGZyb20gd3d3LmFjbWVtaWNyby5j +b20gb3INCnd3dy5yYWNrYWJsZS5jb20gd2l0aCA4eCA0MDBHQiBTQVRBIGRpc2tzIGFuZCB0aGUg +bmV3IDNXYXJlIDk1NTBTWCBTQVRBDQpSQUlEIGNvbnRyb2xsZXIgZm9yIGFib3V0ICQ2SyB3aXRo +IHR3byBPcHRlcm9uIDI3MiBDUFVzIGFuZCA4R0Igb2YgUkFNDQpvbiBhIFR5YW4gMjg4MiBtb3Ro +ZXJib2FyZC4gIFdlIGdldCBhYm91dCA0MDBNQi9zIHN1c3RhaW5lZCBkaXNrIHJlYWQNCnBlcmZv +cm1hbmNlIG9uIHRoZXNlICh3aXRoIHR1bmluZykgb24gTGludXggdXNpbmcgdGhlIHhmcyBmaWxl +c3lzdGVtLA0Kd2hpY2ggaXMgb25lIG9mIHRoZSBtb3N0IGNyaXRpY2FsIGZhY3RvcnMgZm9yIGxh +cmdlIGRhdGFiYXNlcy4gIA0KDQpOb3RlIHRoYXQgeW91IHdhbnQgdG8gaGF2ZSB5b3VyIERCTVMg +dXNlIGFsbCBvZiB0aGUgQ1BVIGFuZCBkaXNrIGNoYW5uZWwNCmJhbmR3aWR0aCB5b3UgaGF2ZSBv +biBlYWNoIHF1ZXJ5LCB3aGljaCB0YWtlcyBhIHBhcmFsbGVsIGRhdGFiYXNlIGxpa2UNCkJpemdy +ZXMgTVBQIHRvIGFjaGlldmUuDQoNClJlZ2FyZHMsDQoNCi0gTHVrZQ0KDQoNClRoZSBXaGF0J3Mg +TmV3IEZBUSBmb3IgUG9zdGdyZVNRTCA4LjEgc2F5cyAidGhlIGJ1ZmZlciBtYW5hZ2VyIGZvciA4 +LjENCmhhcyBiZWVuIGVuaGFuY2VkIHRvIHNjYWxlIGFsbW9zdCBsaW5lYXJseSB3aXRoIHRoZSBu +dW1iZXIgb2YNCnByb2Nlc3NvcnMsIGxlYWRpbmcgdG8gc2lnbmlmaWNhbnQgcGVyZm9ybWFuY2Ug +Z2FpbnMgb24gOC13YXksIDE2LXdheSwNCmR1YWwtY29yZSwgYW5kIG11bHRpLWNvcmUgQ1BVIHNl +cnZlcnMuIg0KDQpXaHkgbm90IGp1c3QgdXNlIGl0IGFzLWlzPw0KDQpDaGVlcnMsDQoNCkFkYW0N +Cg0K + + +From pgsql-performance-owner@postgresql.org Tue Nov 15 12:35:52 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id DEAA0DB82F + for ; + Tue, 15 Nov 2005 12:35:50 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 50572-04 + for ; + Tue, 15 Nov 2005 16:35:48 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from obelix.askesis.nl (laudanum.demon.nl [82.161.125.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 276FBDB831 + for ; + Tue, 15 Nov 2005 12:35:44 -0400 (AST) +Received: obelix.askesis.nl 172.31.0.1 from 172.31.1.8 172.31.1.8 via HTTP + with MS-WebStorage 6.0.6249 +Received: from Panoramix by obelix.askesis.nl; 15 Nov 2005 17:35:42 +0100 +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +From: Joost Kraaijeveld +To: Dave Cramer +Cc: Pgsql-Performance +In-Reply-To: +References: <1131283854.15471.4.camel@Panoramix> + +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Tue, 15 Nov 2005 17:35:42 +0100 +Message-Id: <1132072542.3250.16.camel@Panoramix> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.3 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/252 +X-Sequence-Number: 15509 + +Hi Dave, + +On Mon, 2005-11-14 at 18:51 -0500, Dave Cramer wrote: +> Joost, +> +> I've got experience with these controllers and which version do you +> have. I'd expect to see higher than 50MB/s although I've never tried +> RAID 5 +> +> I routinely see closer to 100MB/s with RAID 1+0 on their 9000 series +OK, than there must be hope. + +> I would also suggest that shared buffers should be higher than 7500, +> closer to 30000, and effective cache should be up around 200k +In my current 8.1 situation I use shared_buffers = 40000, +effective_cache_size = 131072 . + +> work_mem is awfully high, remember that this will be given to each +> and every connection and can be more than 1x this number per +> connection depending on the number of sorts +> done in the query. +I use such a high number because I am the only user querying and my +queries do sorted joins etc. + + +> fsync=false ? I'm not even sure why we have this option, but I'd +> never set it to false. +I want as much speed as possible for a database conversion that MUST be +handled in 1 weekend (it lasts now, with the current speed almost 7 +centuries. I may be off a millenium). If it fails because of hardware +problem (the only reason we want and need fsync?) we will try next +weekend until it finally goes right. + +What I can see is that only the *write* performance of *long updates* +(and not inserts) are slow and they get slower in time: the first few +thousand go relatively fast, after that PostgreSQL crawls to a halt +(other "benchmarks" like bonnie++ or just dd'ing a big file don't have +this behavior). + +I did notice that changing the I/O scheduler's nr_request from the +default 128 to 1024 or even 4096 made a remarkable performance +improvement. I suspect that experimenting with other I/O schedululers +could improve performance. But it is hard to find any useful +documentation about I/O schedulers. + + + +-- +Groeten, + +Joost Kraaijeveld +Askesis B.V. +Molukkenstraat 14 +6524NB Nijmegen +tel: 024-3888063 / 06-51855277 +fax: 024-3608416 +e-mail: J.Kraaijeveld@Askesis.nl +web: www.askesis.nl + + + +From pgsql-performance-owner@postgresql.org Tue Nov 15 14:42:57 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id DE2BBDB831 + for ; + Tue, 15 Nov 2005 14:42:56 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 74148-02 + for ; + Tue, 15 Nov 2005 18:42:55 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id B8556DB86B + for ; + Tue, 15 Nov 2005 14:42:53 -0400 (AST) +Received: from 172.16.1.112 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Tue, 15 Nov 2005 13:42:46 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Tue, 15 Nov + 2005 13:42:23 -0500 +Received: from 67.103.45.218 ([67.103.45.218]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.105]) with Microsoft Exchange Server HTTP-DAV ; Tue, 15 Nov + 2005 13:42:22 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Tue, 15 Nov 2005 10:42:22 -0800 +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +From: "Luke Lonergan" +To: "Joost Kraaijeveld" , + "Dave Cramer" +cc: "Pgsql-Performance" +Message-ID: +Thread-Topic: [PERFORM] Performance PG 8.0 on dual opteron / 4GB / 3ware +Thread-Index: AcXqBJN/YAdpHf0pTdG90SDRQNurAQAD7z3D +In-Reply-To: <1132072542.3250.16.camel@Panoramix> +MIME-Version: 1.0 +X-OriginalArrivalTime: 15 Nov 2005 18:42:23.0641 (UTC) + FILETIME=[516F2090:01C5EA14] +X-WSS-ID: 6F64F3AF31S11621008-09-01 +Content-Type: multipart/alternative; + boundary=B_3214896142_20825174 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[HTML_MESSAGE=0.001, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/253 +X-Sequence-Number: 15510 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3214896142_20825174 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Joost, + +On 11/15/05 8:35 AM, "Joost Kraaijeveld" wrote: + +> thousand go relatively fast, after that PostgreSQL crawls to a halt +> (other "benchmarks" like bonnie++ or just dd'ing a big file don't have +> this behavior). + +With RAID5, it could matter a lot what block size you run your =B3dd bigfile=B2 +test with. You should run =B3dd if=3D/dev/zero of=3Dbigfile bs=3D8k count=3D500000=B2 +for a 2GB main memory machine, multiply the count by (/2GB). + +It is very important with the 3Ware cards to match the driver to the +firmware revision. + =20 +> I did notice that changing the I/O scheduler's nr_request from the +> default 128 to 1024 or even 4096 made a remarkable performance +> improvement. I suspect that experimenting with other I/O schedululers +> could improve performance. But it is hard to find any useful +> documentation about I/O schedulers. +>=20 +You could try deadline, there=B9s no harm, but I=B9ve found that when you reach +the point of experimenting with schedulers, you are probably not addressing +the real problem. +>=20 +On a 3Ware 9500 with HW RAID5 and 4 or more disks I think you should get +100MB/s write rate, which is double what Postgres can use. We find that +Postgres, even with fsync=3Dfalse, will only run at a net COPY speed of about +8-12 MB/s, where 12 is the Bizgres number. 8.1 might do 10. But to get th= +e +10 or 12, the WAL writing and other writing is about 4-5X more than the net +write speed, or the speed at which the input file is parsed and read into +the database. + +So, if you can get your =B3dd bigfile=B2 test to write data at 50MB/s+ with a +blocksize of 8KB, you should be doing well enough. + +Incidentally, we also find that using the XFS filesystem and setting the +readahead to 8MB or more is extremely beneficial for performance with the +3Ware cards (and with others, but especially for the older 3Ware cards). +=20 +Regards, + +- Luke + +--B_3214896142_20825174 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + + + +Re: [PERFORM] Performance PG 8.0 on dual opteron / 4GB / 3ware</TITL= +E> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Joost= +,<BR> +<BR> +On 11/15/05 8:35 AM, "Joost Kraaijeveld" <J.Kraaijeveld@Askesi= +s.nl> wrote:<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>thousand go relatively fast, after that PostgreSQL craw= +ls to a halt<BR> +(other "benchmarks" like bonnie++ or just dd'ing a big file don't= + have<BR> +this behavior).<BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'><BR> +With RAID5, it could matter a lot what block size you run your “dd bi= +gfile” test with.  You should run “dd if=3D/dev/zero of=3Dbigfi= +le bs=3D8k count=3D500000” for a 2GB main memory machine, multiply the cou= +nt by (<your mem>/2GB).<BR> +<BR> +It is very important with the 3Ware cards to match the driver to the firmwa= +re revision.<BR> +   <BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>I did notice that changing the I/O scheduler's nr_reque= +st from the<BR> +default 128 to 1024 or even 4096 made a remarkable performance<BR> +improvement. I suspect that experimenting with other I/O schedululers<BR> +could improve performance. But it is hard to find any useful<BR> +documentation about I/O schedulers.<BR> +<BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'>You could try deadline, there’s no harm, but I&#= +8217;ve found that when you reach the point of experimenting with schedulers= +, you are probably not addressing the real problem.<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'><BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'>On a 3Ware 9500 with HW RAID5 and 4 or more disks I th= +ink you should get 100MB/s write rate, which is double what Postgres can use= +.  We find that Postgres, even with fsync=3Dfalse, will only run at a <B>= +net</B> COPY speed of about 8-12 MB/s, where 12 is the Bizgres number.  = +;8.1 might do 10.  But to get the 10 or 12, the WAL writing and other w= +riting is about 4-5X more than the <B>net</B> write speed, or the speed at w= +hich the input file is parsed and read into the database.<BR> +<BR> +So, if you can get your “dd bigfile” test to write data at 50MB= +/s+ with a blocksize of 8KB, you should be doing well enough.<BR> +<BR> +Incidentally, we also find that using the XFS filesystem and setting the re= +adahead to 8MB or more is extremely beneficial for performance with the 3War= +e cards (and with others, but especially for the older 3Ware cards).<BR> + <BR> +Regards,<BR> +<BR> +- Luke</SPAN></FONT> +</BODY> +</HTML> + + +--B_3214896142_20825174-- + + +From pgsql-performance-owner@postgresql.org Tue Nov 15 14:46:45 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 89408DB847 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 14:46:43 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 74838-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 18:46:42 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw01.mi8.com [63.240.6.47]) + by svr1.postgresql.org (Postfix) with ESMTP id D34BCDB82E + for <pgsql-performance@postgresql.org>; + Tue, 15 Nov 2005 14:46:40 -0400 (AST) +Received: from 172.16.1.110 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D1)); Tue, 15 Nov 2005 13:46:28 -0500 +X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Tue, 15 Nov + 2005 13:46:13 -0500 +Received: from 67.103.45.218 ([67.103.45.218]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.105]) with Microsoft Exchange Server HTTP-DAV ; Tue, 15 Nov + 2005 13:46:12 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Tue, 15 Nov 2005 10:46:12 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Merlin Moncure" <merlin.moncure@rcsonline.com> +cc: pgsql-performance@postgresql.org +Message-ID: <BF9F6CF4.13B4D%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases ( 5TB) +Thread-Index: AcXpvzV5hVFHPWZkSgW5F5EVOZa9hQALkdOwAAEU6wAAACrUAAABI4TAAAdz7qk= +In-Reply-To: <6EE64EF3AB31D5448D0007DD34EEB3417DD898@Herge.rcsinc.local> +MIME-Version: 1.0 +X-OriginalArrivalTime: 15 Nov 2005 18:46:13.0183 (UTC) + FILETIME=[DA4074F0:01C5EA14] +X-WSS-ID: 6F64F28B21G11158571-04-01 +Content-Type: multipart/alternative; + boundary=B_3214896372_20825418 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[HTML_MESSAGE=0.001, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/254 +X-Sequence-Number: 15511 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3214896372_20825418 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Merlin, + +On 11/15/05 7:20 AM, "Merlin Moncure" <merlin.moncure@rcsonline.com> wrote: +>=20 +> It's hard to say what would be better. My gut says the 5u box would be +> a lot better at handling high cpu/high concurrency problems...like your +> typical business erp backend. This is pure speculation of course...I'll +> defer to the experts here. + +With Oracle RAC, which is optimized for OLTP and uses a shared memory +caching model, maybe or maybe not. I=B9d put my money on the SMP in that cas= +e +as you suggest, but what happens when the OS dies? + +For data warehousing, OLAP and decision support applications, RAC and other +shared memory/disk architectures don=B9t do you any good and the SMP machine +is better by a bit. + +However, if you have an MPP database, where disk and memory are not shared, +then the SMP machine is tens or hundreds of times slower than the cluster o= +f +the same price. + +- Luke=20 + + +--B_3214896372_20825418 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +<HTML> +<HEAD> +<TITLE>Re: [PERFORM] Hardware/OS recommendations for large databases ( 5TB)= + + + +Merli= +n,
+
+On 11/15/05 7:20 AM, "Merlin Moncure" <merlin.moncure@rcsonlin= +e.com> wrote:
+

+It's hard to say what would be better.  My gut says the 5u box would b= +e
+a lot better at handling high cpu/high concurrency problems...like your
+typical business erp backend.  This is pure speculation of course...I'= +ll
+defer to the experts here.
+

+With Oracle RAC, which is optimized for OLTP and uses a shared memory cachi= +ng model, maybe or maybe not.  I’d put my money on the SMP in tha= +t case as you suggest, but what happens when the OS dies?
+
+For data warehousing, OLAP and decision support applications, RAC and other= + shared memory/disk architectures don’t do you any good and the SMP ma= +chine is better by a bit.
+
+However, if you have an MPP database, where disk and memory are not shared,= + then the SMP machine is tens or hundreds of times slower than the cluster o= +f the same price.
+
+- Luke
+ + + + + +--B_3214896372_20825418-- + + +From pgsql-performance-owner@postgresql.org Tue Nov 15 14:48:21 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 779FDDB8BA + for ; + Tue, 15 Nov 2005 14:48:20 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 74252-04 + for ; + Tue, 15 Nov 2005 18:48:19 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw02.mi8.com [63.240.6.46]) + by svr1.postgresql.org (Postfix) with ESMTP id 12DB1DB8AE + for ; + Tue, 15 Nov 2005 14:48:16 -0400 (AST) +Received: from 172.16.1.112 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D2)); Tue, 15 Nov 2005 13:48:09 -0500 +X-Server-Uuid: 7829E76E-BB9E-4995-8473-3C0929DF7DD1 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Tue, 15 Nov + 2005 13:48:00 -0500 +Received: from 67.103.45.218 ([67.103.45.218]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.105]) with Microsoft Exchange Server HTTP-DAV ; Tue, 15 Nov + 2005 13:47:59 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Tue, 15 Nov 2005 10:47:59 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" +To: "Michael Stone" +cc: pgsql-performance@postgresql.org +Message-ID: +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXp9Rz/g4t+KwF1QzeAxs8MLl6yOQAH/xTB +In-Reply-To: <20051115145545.GQ9905@mathom.us> +MIME-Version: 1.0 +X-OriginalArrivalTime: 15 Nov 2005 18:48:00.0510 (UTC) + FILETIME=[1A3941E0:01C5EA15] +X-WSS-ID: 6F64F2ED2RS6959392-17-01 +Content-Type: multipart/alternative; + boundary=B_3214896479_20817725 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[HTML_MESSAGE=0.001, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/255 +X-Sequence-Number: 15512 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3214896479_20817725 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Mike,=20 + +On 11/15/05 6:55 AM, "Michael Stone" wrote: + +> On Tue, Nov 15, 2005 at 09:33:25AM -0500, Luke Lonergan wrote: +>> >write performance is now up to par with the best cards I believe. We +>> >find that you still need to set Linux readahead to at least 8MB +>> >(blockdev --setra) to get maximum read performance on them, is that you= +r +>=20 +> What on earth does that do to your seek performance? + +We=B9re in decision support, as is our poster here, so seek isn=B9t the issue, +it=B9s sustained sequential transfer rate that we need. At 8MB, I=B9d not +expect too much damage though =AD the default is 1.5MB. + +- Luke +>=20 + + + +--B_3214896479_20817725 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + + + +Re: [PERFORM] Hardware/OS recommendations for large databases (</TIT= +LE> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Mike,= + <BR> +<BR> +On 11/15/05 6:55 AM, "Michael Stone" <mstone+postgres@mathom.u= +s> wrote:<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>On Tue, Nov 15, 2005 at 09:33:25AM -0500, Luke Lonergan= + wrote:<BR> +>write performance is now up to par with the best cards I believe.  = +;We<BR> +>find that you still need to set Linux readahead to at least 8MB<BR> +>(blockdev --setra) to get maximum read performance on them, is that you= +r<BR> +<BR> +What on earth does that do to your seek performance?<BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'><BR> +We’re in decision support, as is our poster here, so seek isn’t= + the issue, it’s sustained sequential transfer rate that we need. &nbs= +p;At 8MB, I’d not expect too much damage though – the default is= + 1.5MB.<BR> +<BR> +- Luke<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'><BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'><BR> +</SPAN></FONT> +</BODY> +</HTML> + + +--B_3214896479_20817725-- + + +From pgsql-performance-owner@postgresql.org Tue Nov 15 15:00:21 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id DDE15DB7F0 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 14:57:12 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 75881-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 18:57:12 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id EDD90D71C1 + for <pgsql-performance@postgresql.org>; + Tue, 15 Nov 2005 14:57:09 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id 0322F31059; Tue, 15 Nov 2005 19:57:10 +0100 (MET) +From: William Yu <wyu@talisys.com> +X-Newsgroups: pgsql.performance +Subject: Re: Hardware/OS recommendations for large databases ( 5TB) +Date: Tue, 15 Nov 2005 10:57:05 -0800 +Organization: Hub.Org Networking Services +Lines: 15 +Message-ID: <dldb20$2lau$1@news.hub.org> +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD898@Herge.rcsinc.local> +Mime-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +User-Agent: Mozilla Thunderbird 1.0 (X11/20041206) +X-Accept-Language: en-us, en +In-Reply-To: <6EE64EF3AB31D5448D0007DD34EEB3417DD898@Herge.rcsinc.local> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/256 +X-Sequence-Number: 15513 + +Merlin Moncure wrote: +>>You could instead buy 8 machines that total 16 cores, 128GB RAM and +> +> It's hard to say what would be better. My gut says the 5u box would be +> a lot better at handling high cpu/high concurrency problems...like your +> typical business erp backend. This is pure speculation of course...I'll +> defer to the experts here. + +In this specific case (data warehouse app), multiple machines is the +better bet. Load data on 1 machine, copy to other servers and then use a +middleman to spread out SQL statements to each machine. + +I was going to suggest pgpool as the middleman but I believe it's +limited to 2 machines max at this time. I suppose you could daisy chain +pgpools running on every machine. + +From pgsql-performance-owner@postgresql.org Tue Nov 15 18:08:31 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 78896D7C5C + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 18:08:29 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 18909-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 22:08:30 +0000 (GMT) +X-Greylist: delayed 03:00:40.837875 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 520FDD6837 + for <pgsql-performance@postgresql.org>; + Tue, 15 Nov 2005 18:08:25 -0400 (AST) +Received: from jupiter.ad.haydrian.com (nat.haydrian.com [70.98.72.98]) + by svr2.postgresql.org (Postfix) with ESMTP id 62F96F139B + for <pgsql-performance@postgresql.org>; + Tue, 15 Nov 2005 19:07:43 +0000 (GMT) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Hardware/OS recommendations for large databases ( 5TB) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Date: Tue, 15 Nov 2005 11:07:40 -0800 +Message-ID: <775F825B46B551499DC75DC4E92F80AB0E3623@jupiter.ad.haydrian.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases ( 5TB) +thread-index: AcXqF1J+4GMu4DJdRoSAkms/8lt9bwAADWww +From: "James Mello" <james@haydrian.com> +To: "William Yu" <wyu@talisys.com>, + <pgsql-performance@postgresql.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/262 +X-Sequence-Number: 15519 + +Unless there was a way to guarantee consistency, it would be hard at +best to make this work. Convergence on large data sets across boxes is +non-trivial, and diffing databases is difficult at best. Unless there +was some form of automated way to ensure consistency, going 8 ways into +separate boxes is *very* hard. I do suppose that if you have fancy +storage (EMC, Hitachi) you could do BCV or Shadow copies. But in terms +of commodity stuff, I'd have to agree with Merlin.=20 + +-----Original Message----- +From: pgsql-performance-owner@postgresql.org +[mailto:pgsql-performance-owner@postgresql.org] On Behalf Of William Yu +Sent: Tuesday, November 15, 2005 10:57 AM +To: pgsql-performance@postgresql.org +Subject: Re: [PERFORM] Hardware/OS recommendations for large databases ( +5TB) + +Merlin Moncure wrote: +>>You could instead buy 8 machines that total 16 cores, 128GB RAM and +> =20 +> It's hard to say what would be better. My gut says the 5u box would=20 +> be a lot better at handling high cpu/high concurrency problems...like=20 +> your typical business erp backend. This is pure speculation of=20 +> course...I'll defer to the experts here. + +In this specific case (data warehouse app), multiple machines is the +better bet. Load data on 1 machine, copy to other servers and then use a +middleman to spread out SQL statements to each machine. + +I was going to suggest pgpool as the middleman but I believe it's +limited to 2 machines max at this time. I suppose you could daisy chain +pgpools running on every machine. + +---------------------------(end of broadcast)--------------------------- +TIP 9: In versions below 8.0, the planner will ignore your desire to + choose an index scan if your joining column's datatypes do not + match + +From pgsql-performance-owner@postgresql.org Tue Nov 15 15:38:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B5B2FDB831 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 15:38:48 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 79202-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 19:38:48 +0000 (GMT) +X-Greylist: delayed 00:26:17.566921 by SQLgrey- +Received: from bfccomputing.com (bfccomputing.com [217.160.248.65]) + by svr1.postgresql.org (Postfix) with ESMTP id A49C9DB876 + for <pgsql-performance@postgresql.org>; + Tue, 15 Nov 2005 15:38:45 -0400 (AST) +Received: from [10.0.0.202] (68-169-200-61.sbtnvt.adelphia.net + [68.169.200.61]) + by bfccomputing.com (Postfix) with ESMTP id 00D81E8038 + for <pgsql-performance@postgresql.org>; + Tue, 15 Nov 2005 14:12:13 -0500 (EST) +Mime-Version: 1.0 (Apple Message framework v623) +Content-Transfer-Encoding: 7bit +Message-Id: <e11403f0198a3591a66d8c28f0cd9b61@bfccomputing.com> +Content-Type: text/plain; charset=US-ASCII; format=flowed +To: pgsql-performance@postgresql.org +From: Bill McGonigle <bill@bfccomputing.com> +Subject: Too Many OR's? +Date: Tue, 15 Nov 2005 14:12:23 -0500 +X-Mailer: Apple Mail (2.623) +X-bfccomputing-MailScanner-Information: Please contact the ISP for more + information +X-bfccomputing-MailScanner: Found to be clean +X-bfccomputing-MailScanner-SpamCheck: +X-MailScanner-From: bill@bfccomputing.com +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/258 +X-Sequence-Number: 15515 + +I have a query that's making the planner do the wrong thing (for my +definition of wrong) and I'm looking for advice on what to tune to make +it do what I want. + +The query consists or SELECT'ing a few fields from a table for a large +number of rows. The table has about seventy thousand rows and the user +is selecting some subset of them. I first do a SELECT...WHERE to +determine the unique identifiers I want (works fine) and then I do a +SELECT WHERE IN giving the list of id's I need additional data on +(which I see from EXPLAIN just gets translated into a very long list of +OR's). + +Everything works perfectly until I get to 65301 rows. At 65300 rows, +it does an index scan and takes 2197.193 ms. At 65301 rows it switches +to a sequential scan and takes 778951.556 ms. Values known not to +affect this are: work_mem, effective_cache_size. Setting +random_page_cost from 4 to 1 helps (79543.214 ms) but I'm not really +sure what '1' means, except it's relative. Of course, setting +'enable_seqscan false' helps immensely (2337.289 ms) but that's as +inelegant of a solution as I've found - if there were other databases +on this install that wouldn't be the right approach. + +Now I can break this down into multiple SELECT's in code, capping each +query at 65300 rows, and that's a usable workaround, but academically +I'd like to know how to convince the planner to do it my way. It's +making a bad guess about something but I'm not sure what. I didn't see +any hard-coded limits grepping through the source (though it is close +to the 16-bit unsigned boundry - probably coincidental) so if anyone +has ideas or pointers to how I might figure out what's going wrong that +would be helpful. + +Thanks, +-Bill + +----- +Bill McGonigle, Owner Work: 603.448.4440 +BFC Computing, LLC Home: 603.448.1668 +bill@bfccomputing.com Mobile: 603.252.2606 +http://www.bfccomputing.com/ Pager: 603.442.1833 +Jabber: flowerpt@gmail.com Text: bill+text@bfccomputing.com +Blog: http://blog.bfccomputing.com/ + + +From pgsql-performance-owner@postgresql.org Tue Nov 15 15:32:02 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id ABA1CDACDE + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 15:32:01 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 79102-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 19:32:00 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from obelix.askesis.nl (laudanum.demon.nl [82.161.125.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 1CAE5D9443 + for <pgsql-performance@postgresql.org>; + Tue, 15 Nov 2005 15:31:57 -0400 (AST) +Received: obelix.askesis.nl 172.31.0.1 from 172.31.1.8 172.31.1.8 via HTTP + with MS-WebStorage 6.0.6249 +Received: from Panoramix by obelix.askesis.nl; 15 Nov 2005 20:31:56 +0100 +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +From: Joost Kraaijeveld <J.Kraaijeveld@Askesis.nl> +To: Luke Lonergan <llonergan@greenplum.com> +Cc: Dave Cramer <pg@fastcrypt.com>, + Pgsql-Performance <pgsql-performance@postgresql.org> +In-Reply-To: <BF9F6C0E.13B4A%llonergan@greenplum.com> +References: <BF9F6C0E.13B4A%llonergan@greenplum.com> +Content-Type: text/plain; charset=iso-8859-13 +Content-Transfer-Encoding: quoted-printable +Date: Tue, 15 Nov 2005 20:31:56 +0100 +Message-Id: <1132083116.3250.38.camel@Panoramix> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.3 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/257 +X-Sequence-Number: 15514 + +Hi Luke, + +On Tue, 2005-11-15 at 10:42 -0800, Luke Lonergan wrote: +> With RAID5, it could matter a lot what block size you run your =B4dd +> bigfile=A1 test with. You should run =B4dd if=3D/dev/zero of=3Dbigfile b= +s=3D8k +> count=3D500000=A1 for a 2GB main memory machine, multiply the count by +> (<your mem>/2GB). +If I understand correctly (I have 4GB ram): + +jkr@Panoramix:~/tmp$ dd if=3D/dev/zero of=3Dbigfile bs=3D8k count=3D1000000 +1000000+0 records in +1000000+0 records out +8192000000 bytes transferred in 304.085269 seconds (26939812 bytes/sec) + +Which looks suspicious: 26308 MB/sec??? + +> It is very important with the 3Ware cards to match the driver to the +> firmware revision. +OK, I am running 1 driver behind the firmware. + =20 +> I did notice that changing the I/O scheduler's nr_request from +> the +> default 128 to 1024 or even 4096 made a remarkable performance +> improvement. I suspect that experimenting with other I/O +> schedululers +> could improve performance. But it is hard to find any useful +> documentation about I/O schedulers. +> =20 +> You could try deadline, there=FFs no harm, but I=FFve found that when you +> reach the point of experimenting with schedulers, you are probably not +> addressing the real problem. +It depends. I/O Schedulers (I assume) have a purpose: some schedulers +should be more appropriate for some circumstances. And maybe my specific +circumstances (converting a database with *many updates*) is a specific +circumstance. I really don't know.... + +> On a 3Ware 9500 with HW RAID5 and 4 or more disks I think you should +> get 100MB/s write rate, which is double what Postgres can use. We +> find that Postgres, even with fsync=3Dfalse, will only run at a net COPY +> speed of about 8-12 MB/s, where 12 is the Bizgres number. 8.1 might +> do 10. But to get the 10 or 12, the WAL writing and other writing is +> about 4-5X more than the net write speed, or the speed at which the +> input file is parsed and read into the database. +As I have an (almost) seperate WAL disk: iostat does not show any +significant writing on the WAL disk.... + +> So, if you can get your =B4dd bigfile=A1 test to write data at 50MB/s+ +> with a blocksize of 8KB, you should be doing well enough. +See above. + +> Incidentally, we also find that using the XFS filesystem and setting +> the readahead to 8MB or more is extremely beneficial for performance +> with the 3Ware cards (and with others, but especially for the older +> 3Ware cards). +I don't have problems with my read performance but *only* with my +*update* performance (and not even insert performance). But than again I +am not the only one with these problems: + +http://www.issociate.de/board/goto/894541/3ware_+_RAID5_ ++_xfs_performance.html#msg_894541 +http://lkml.org/lkml/2005/4/20/110 +http://seclists.org/lists/linux-kernel/2005/Oct/1171.html + +I am happy to share the tables against which I am running my checks.... + +--=20 +Groeten, + +Joost Kraaijeveld +Askesis B.V. +Molukkenstraat 14 +6524NB Nijmegen +tel: 024-3888063 / 06-51855277 +fax: 024-3608416 +e-mail: J.Kraaijeveld@Askesis.nl +web: www.askesis.nl=20 + + + +From pgsql-performance-owner@postgresql.org Tue Nov 15 15:41:29 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 703FADB863 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 15:41:28 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 94531-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 19:41:28 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from noao.edu (noao.edu [140.252.1.54]) + by svr1.postgresql.org (Postfix) with ESMTP id AEEBADB81F + for <pgsql-performance@postgresql.org>; + Tue, 15 Nov 2005 15:41:25 -0400 (AST) +X-TFF-CGPSA-Version: 1.4f1 +X-TFF-CGPSA-Filter: Scanned +Received: from weaver.tuc.noao.edu ([140.252.14.8] verified) + by noao.edu (CommuniGate Pro SMTP 5.0.1) + with ESMTPS id 21653526; Tue, 15 Nov 2005 12:41:24 -0700 +Received: from [127.0.0.1] (localhost.localdomain [127.0.0.1]) + by weaver.tuc.noao.edu (8.13.1/8.13.1) with ESMTP id jAFJfNhp000509; + Tue, 15 Nov 2005 12:41:23 -0700 +Message-ID: <437A39E3.6030707@noao.edu> +Date: Tue, 15 Nov 2005 12:41:23 -0700 +From: Steve Wampler <swampler@noao.edu> +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Joost Kraaijeveld <J.Kraaijeveld@Askesis.nl> +CC: Luke Lonergan <llonergan@greenplum.com>, Dave Cramer <pg@fastcrypt.com>, + Pgsql-Performance <pgsql-performance@postgresql.org> +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +References: <BF9F6C0E.13B4A%llonergan@greenplum.com> + <1132083116.3250.38.camel@Panoramix> +In-Reply-To: <1132083116.3250.38.camel@Panoramix> +Content-Type: text/plain; charset=ISO-8859-13 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/259 +X-Sequence-Number: 15516 + +Joost Kraaijeveld wrote: +> If I understand correctly (I have 4GB ram): +> +> jkr@Panoramix:~/tmp$ dd if=/dev/zero of=bigfile bs=8k count=1000000 +> 1000000+0 records in +> 1000000+0 records out +> 8192000000 bytes transferred in 304.085269 seconds (26939812 bytes/sec) +> +> Which looks suspicious: 26308 MB/sec??? + +Eh? That looks more like ~25.7 MB/sec, assuming 1MB = 1024*1024 bytes. + +-- +Steve Wampler -- swampler@noao.edu +The gods that smiled on your birth are now laughing out loud. + +From pgsql-performance-owner@postgresql.org Tue Nov 15 15:51:32 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 673C3DB82F + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 15:51:31 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 96461-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 19:51:31 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from obelix.askesis.nl (laudanum.demon.nl [82.161.125.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 4920EDB7C7 + for <pgsql-performance@postgresql.org>; + Tue, 15 Nov 2005 15:51:27 -0400 (AST) +Received: obelix.askesis.nl 172.31.0.1 from 172.31.1.8 172.31.1.8 via HTTP + with MS-WebStorage 6.0.6249 +Received: from Panoramix by obelix.askesis.nl; 15 Nov 2005 20:51:28 +0100 +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +From: Joost Kraaijeveld <J.Kraaijeveld@Askesis.nl> +To: Steve Wampler <swampler@noao.edu> +Cc: Luke Lonergan <llonergan@greenplum.com>, Dave Cramer <pg@fastcrypt.com>, + Pgsql-Performance <pgsql-performance@postgresql.org> +In-Reply-To: <437A39E3.6030707@noao.edu> +References: <BF9F6C0E.13B4A%llonergan@greenplum.com> + <1132083116.3250.38.camel@Panoramix> <437A39E3.6030707@noao.edu> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Tue, 15 Nov 2005 20:51:27 +0100 +Message-Id: <1132084287.3250.41.camel@Panoramix> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.3 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/260 +X-Sequence-Number: 15517 + +On Tue, 2005-11-15 at 12:41 -0700, Steve Wampler wrote: +> Joost Kraaijeveld wrote: +> > If I understand correctly (I have 4GB ram): +> > +> > jkr@Panoramix:~/tmp$ dd if=/dev/zero of=bigfile bs=8k count=1000000 +> > 1000000+0 records in +> > 1000000+0 records out +> > 8192000000 bytes transferred in 304.085269 seconds (26939812 bytes/sec) +> > +> > Which looks suspicious: 26308 MB/sec??? +> +> Eh? That looks more like ~25.7 MB/sec, assuming 1MB = 1024*1024 bytes. +Oooops. This calculation error is not typical for my testing (I think ;-)). + +-- +Groeten, + +Joost Kraaijeveld +Askesis B.V. +Molukkenstraat 14 +6524NB Nijmegen +tel: 024-3888063 / 06-51855277 +fax: 024-3608416 +e-mail: J.Kraaijeveld@Askesis.nl +web: www.askesis.nl + + + +From pgsql-performance-owner@postgresql.org Tue Nov 15 16:01:57 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 18F01DACDE + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 16:01:51 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 95644-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 15 Nov 2005 20:01:50 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from koolancexeon.g2switchworks.com (mail.g2switchworks.com + [63.87.162.25]) + by svr1.postgresql.org (Postfix) with ESMTP id D1775D9443 + for <pgsql-performance@postgresql.org>; + Tue, 15 Nov 2005 16:01:47 -0400 (AST) +Received: mail.g2switchworks.com 10.10.1.8 from 10.10.1.37 10.10.1.37 via HTTP + with MS-WebStorage 6.5.6944 +Received: from state.g2switchworks.com by mail.g2switchworks.com; + 15 Nov 2005 14:01:48 -0600 +Subject: Re: Too Many OR's? +From: Scott Marlowe <smarlowe@g2switchworks.com> +To: Bill McGonigle <bill@bfccomputing.com> +Cc: pgsql-performance@postgresql.org +In-Reply-To: <e11403f0198a3591a66d8c28f0cd9b61@bfccomputing.com> +References: <e11403f0198a3591a66d8c28f0cd9b61@bfccomputing.com> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Message-Id: <1132084908.3582.46.camel@state.g2switchworks.com> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) +Date: Tue, 15 Nov 2005 14:01:48 -0600 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/261 +X-Sequence-Number: 15518 + +On Tue, 2005-11-15 at 13:12, Bill McGonigle wrote: +> I have a query that's making the planner do the wrong thing (for my +> definition of wrong) and I'm looking for advice on what to tune to make +> it do what I want. +> +> The query consists or SELECT'ing a few fields from a table for a large +> number of rows. The table has about seventy thousand rows and the user +> is selecting some subset of them. I first do a SELECT...WHERE to +> determine the unique identifiers I want (works fine) and then I do a +> SELECT WHERE IN giving the list of id's I need additional data on +> (which I see from EXPLAIN just gets translated into a very long list of +> OR's). +> +> Everything works perfectly until I get to 65301 rows. At 65300 rows, +> it does an index scan and takes 2197.193 ms. At 65301 rows it switches +> to a sequential scan and takes 778951.556 ms. Values known not to +> affect this are: work_mem, effective_cache_size. Setting +> random_page_cost from 4 to 1 helps (79543.214 ms) but I'm not really +> sure what '1' means, except it's relative. Of course, setting +> 'enable_seqscan false' helps immensely (2337.289 ms) but that's as +> inelegant of a solution as I've found - if there were other databases +> on this install that wouldn't be the right approach. +> +> Now I can break this down into multiple SELECT's in code, capping each +> query at 65300 rows, and that's a usable workaround, but academically +> I'd like to know how to convince the planner to do it my way. It's +> making a bad guess about something but I'm not sure what. I didn't see +> any hard-coded limits grepping through the source (though it is close +> to the 16-bit unsigned boundry - probably coincidental) so if anyone +> has ideas or pointers to how I might figure out what's going wrong that +> would be helpful. + +OK, there IS a point at which switching to a sequential scan will be +fast. I.e. when you're getting everything in the table. But the +database is picking a number where to switch that is too low. + +First, we need to know if the statistics are giving the query planner a +good enough idea of how many rows it's really gonna get versus how many +it expects. + +Do an explain <your query here> and see how many it thinks it's gonna +get. Since you've actually run it, you know how many it really is going +to get, so there's no need for an explain analyze <your query here> just +yet. + +Now, as long as the approximation is pretty close, fine. But if it's +off by factors, then we need to increase the statistics target on that +column, with: + +ALTER TABLE name ALTER columnname SET STATISTICS xxx + +where xxx is the new number. The default is set in your postgresql.conf +file, and is usually pretty low, say 10. You can go up to 1000, but +that makes query planning take longer. Try some incremental increase to +say 20 or 40 or even 100, and run analyze on that table then do an +explain on it again until the estimate is close. + +Once the estimate is close, you use change random_page_cost to get the +query planner to switch at the "right" time. Change the number of in() +numbers and play with random_page_cost and see where that sweet spot +is. note that what seems right on a single table for a single user may +not be best as you increase load or access other tables. + +random_page_cost represents the increase in a random access versus a +sequential access. As long as your data fit into ram, the difference is +pretty much none (i.e. random_page_cost=1) so don't set it too low, or +accessing REALLY large data sets could become REALLY slow, as it uses +indexes when it should have been sequentially scanning. + +Also, check what you've got effective_cache set to. This tells +postgresql how much memory your kernel is using for cache, and so lets +it know about how likely it is that your current data set under your +query is to be in there. + +Also, read this: + +http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html + +From pgsql-performance-owner@postgresql.org Wed Nov 16 01:15:41 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 31112DB81F + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 01:15:40 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 81679-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 05:15:37 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.202]) + by svr1.postgresql.org (Postfix) with ESMTP id 31FAADB84A + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 01:15:35 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id 57so1371384wri + for <pgsql-performance@postgresql.org>; + Tue, 15 Nov 2005 21:15:36 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=oCGFowuiDAtXKrByESLCdY3Lv+hWXSlny+rvTS+n7ylmjDTruSde9XhlC8CUASI7/xzLLWPGAUlA9ILEzM/M5HNkS2jgEEZ51b4qbcNopjMiOwwQb4T2qkmJEpNpNMVbkOlTxMi+bUS9gXPbg7RzZezyj6SZImcUf00G6wXrw4w= +Received: by 10.54.66.3 with SMTP id o3mr3246183wra; + Tue, 15 Nov 2005 21:15:36 -0800 (PST) +Received: by 10.54.82.5 with HTTP; Tue, 15 Nov 2005 21:15:36 -0800 (PST) +Message-ID: <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> +Date: Wed, 16 Nov 2005 00:15:36 -0500 +From: Alex Turner <armtuk@gmail.com> +To: Luke Lonergan <LLonergan@greenplum.com> +Subject: Re: Hardware/OS recommendations for large databases ( +Cc: Adam Weisberg <Aweisberg@seiu1199.org>, pgsql-performance@postgresql.org +In-Reply-To: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/263 +X-Sequence-Number: 15520 + +On 11/15/05, Luke Lonergan <LLonergan@greenplum.com> wrote: +> Adam, +> +> > -----Original Message----- +> > From: pgsql-performance-owner@postgresql.org +> > [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of +> > Claus Guttesen +> > Sent: Tuesday, November 15, 2005 12:29 AM +> > To: Adam Weisberg +> > Cc: pgsql-performance@postgresql.org +> > Subject: Re: [PERFORM] Hardware/OS recommendations for large +> > databases ( 5TB) +> > +> > > Does anyone have recommendations for hardware and/or OS to +> > work with +> > > around 5TB datasets? +> > +> > Hardware-wise I'd say dual core opterons. One +> > dual-core-opteron performs better than two single-core at the +> > same speed. Tyan makes some boards that have four sockets, +> > thereby giving you 8 cpu's (if you need that many). Sun and +> > HP also makes nice hardware although the Tyan board is more +> > competetive priced. +> > +> > OS wise I would choose the FreeBSD amd64 port but +> > partititions larger than 2 TB needs some special care, using +> > gpt rather than disklabel etc., tools like fsck may not be +> > able to completely check partitions larger than 2 TB. Linux +> > or Solaris with either LVM or Veritas FS sounds like candidates. +> +> I agree - you can get a very good one from www.acmemicro.com or +> www.rackable.com with 8x 400GB SATA disks and the new 3Ware 9550SX SATA +> RAID controller for about $6K with two Opteron 272 CPUs and 8GB of RAM +> on a Tyan 2882 motherboard. We get about 400MB/s sustained disk read +> performance on these (with tuning) on Linux using the xfs filesystem, +> which is one of the most critical factors for large databases. +> + +Spend a fortune on dual core CPUs and then buy crappy disks... I bet +for most applications this system will be IO bound, and you will see a +nice lot of drive failures in the first year of operation with +consumer grade drives. + +Spend your money on better Disks, and don't bother with Dual Core IMHO +unless you can prove the need for it. + +Alex + +From pgsql-performance-owner@postgresql.org Wed Nov 16 01:17:03 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9AFC8D98C9 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 01:17:01 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 81862-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 05:17:00 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.203]) + by svr1.postgresql.org (Postfix) with ESMTP id 088DDD6D8C + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 01:16:57 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id 57so1371511wri + for <pgsql-performance@postgresql.org>; + Tue, 15 Nov 2005 21:16:58 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=XaYXW3ZUpTMVJdW+unj/oK01MIfa71QAf1+nMLWCCdnm2PBfLWXjhFf6tbfd5V596ox8UUnUvdvnMK8D5g7y96qc02p1y0utx2rKyLqjbirFD+VPxtScl3HBzEERRO74JeQWAOoZvmwFzKTG1wjAgR5B1d9fo4EzGmxr8o9rTFI= +Received: by 10.54.114.5 with SMTP id m5mr3159000wrc; + Tue, 15 Nov 2005 21:16:58 -0800 (PST) +Received: by 10.54.82.5 with HTTP; Tue, 15 Nov 2005 21:16:58 -0800 (PST) +Message-ID: <33c6269f0511152116s4483af82s91c711b1b902da14@mail.gmail.com> +Date: Wed, 16 Nov 2005 00:16:58 -0500 +From: Alex Turner <armtuk@gmail.com> +To: Dave Cramer <pg@fastcrypt.com> +Subject: Re: Hardware/OS recommendations for large databases ( +Cc: Luke Lonergan <LLonergan@greenplum.com>, + Adam Weisberg <Aweisberg@seiu1199.org>, pgsql-performance@postgresql.org +In-Reply-To: <B41A9E46-AC4F-4A3A-B383-AB70091745CF@fastcrypt.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <B41A9E46-AC4F-4A3A-B383-AB70091745CF@fastcrypt.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/264 +X-Sequence-Number: 15521 + +Not at random access in RAID 10 they aren't, and anyone with their +head screwed on right is using RAID 10. The 9500S will still beat the +Areca cards at RAID 10 database access patern. + +Alex. + +On 11/15/05, Dave Cramer <pg@fastcrypt.com> wrote: +> Luke, +> +> Have you tried the areca cards, they are slightly faster yet. +> +> Dave +> +> On 15-Nov-05, at 7:09 AM, Luke Lonergan wrote: +> +> +> +> +> +> I agree - you can get a very good one from www.acmemicro.com or +> +> www.rackable.com with 8x 400GB SATA disks and the new 3Ware 9550SX SATA +> +> RAID controller for about $6K with two Opteron 272 CPUs and 8GB of RAM +> +> on a Tyan 2882 motherboard. We get about 400MB/s sustained disk read +> +> performance on these (with tuning) on Linux using the xfs filesystem, +> +> which is one of the most critical factors for large databases. +> +> +> +> +> Note that you want to have your DBMS use all of the CPU and disk channel +> +> bandwidth you have on each query, which takes a parallel database like +> +> Bizgres MPP to achieve. +> +> +> +> +> Regards, +> + +From pgsql-performance-owner@postgresql.org Wed Nov 16 02:08:34 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 998B2DB8A8 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 02:08:31 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 86531-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 06:08:30 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id BF10FDB86C + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 02:08:26 -0400 (AST) +Received: from 172.16.1.110 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Wed, 16 Nov 2005 01:07:55 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Wed, 16 Nov + 2005 01:07:55 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Wed, 16 Nov + 2005 01:07:54 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Tue, 15 Nov 2005 22:07:53 -0800 +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Joost Kraaijeveld" <J.Kraaijeveld@Askesis.nl>, + "Steve Wampler" <swampler@noao.edu> +cc: "Dave Cramer" <pg@fastcrypt.com>, + "Pgsql-Performance" <pgsql-performance@postgresql.org> +Message-ID: <BFA00CB9.13C63%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Performance PG 8.0 on dual opteron / 4GB / 3ware +Thread-Index: AcXqHf6+BJAUyQ2hSW+ZhaRz2DqctQAVhWwm +In-Reply-To: <1132084287.3250.41.camel@Panoramix> +MIME-Version: 1.0 +X-OriginalArrivalTime: 16 Nov 2005 06:07:55.0203 (UTC) + FILETIME=[15C16930:01C5EA74] +X-WSS-ID: 6F64133131S12016986-01-01 +Content-Type: multipart/alternative; + boundary=B_3214937273_22952610 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[HTML_MESSAGE=0.001, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/265 +X-Sequence-Number: 15522 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3214937273_22952610 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Joost, + +On 11/15/05 11:51 AM, "Joost Kraaijeveld" <J.Kraaijeveld@Askesis.nl> wrote: + +> On Tue, 2005-11-15 at 12:41 -0700, Steve Wampler wrote: +>> > Joost Kraaijeveld wrote: +>>> > > If I understand correctly (I have 4GB ram): +>>> > > +>>> > > jkr@Panoramix:~/tmp$ dd if=3D/dev/zero of=3Dbigfile bs=3D8k count=3D1000000 +>>> > > 1000000+0 records in +>>> > > 1000000+0 records out +>>> > > 8192000000 bytes transferred in 304.085269 seconds (26939812 bytes/= +sec) +>>> > > +>>> > > Which looks suspicious: 26308 MB/sec??? +>> > +>> > Eh? That looks more like ~25.7 MB/sec, assuming 1MB =3D 1024*1024 bytes= +. +> Oooops. This calculation error is not typical for my testing (I think ;-)= +). + +Summarizing the two facts of note: the write result is 1/4 of what you +should be getting, and you are running 1 driver behind the firmware. + +You might update your driver, rerun the test, and if you still have the slo= +w +result, verify that your filesystem isn=B9t fragmented (multiple undiscipline= +d +apps on the same filesystem will do that). + +WAL on a separate disk, on a separate controller? What is the write +performance there? + +Regards, + +- Luke + +--B_3214937273_22952610 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +<HTML> +<HEAD> +<TITLE>Re: [PERFORM] Performance PG 8.0 on dual opteron / 4GB / 3ware</TITL= +E> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Joost= +,<BR> +<BR> +On 11/15/05 11:51 AM, "Joost Kraaijeveld" <J.Kraaijeveld@Askes= +is.nl> wrote:<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>On Tue, 2005-11-15 at 12:41 -0700, Steve Wampler wrote:= +<BR> +> Joost Kraaijeveld wrote:<BR> +> > If I understand correctly (I have 4GB ram):<BR> +> ><BR> +> > jkr@Panoramix:~/tmp$ dd if=3D/dev/zero of=3Dbigfile bs=3D8k count=3D10000= +00<BR> +> > 1000000+0 records in<BR> +> > 1000000+0 records out<BR> +> > 8192000000 bytes transferred in 304.085269 seconds (26939812 byte= +s/sec)<BR> +> ><BR> +> > Which looks suspicious: 26308 MB/sec???<BR> +><BR> +> Eh?  That looks more like ~25.7 MB/sec, assuming 1MB =3D 1024*1024 = +bytes.<BR> +Oooops. This calculation error is not typical for my testing (I think ;-)).= +<BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'><BR> +Summarizing the two facts of note: the write result is 1/4 of what you shou= +ld be getting, and you are running 1 driver behind the firmware.<BR> +<BR> +You might update your driver, rerun the test, and if you still have the slo= +w result, verify that your filesystem isn’t fragmented (multiple undis= +ciplined apps on the same filesystem will do that).<BR> +<BR> +WAL on a separate disk, on a separate controller?  What is the write p= +erformance there?<BR> +<BR> +Regards,<BR> +<BR> +- Luke</SPAN></FONT> +</BODY> +</HTML> + + +--B_3214937273_22952610-- + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 02:12:50 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 57DE7DAD2C + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 02:12:49 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 87854-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 06:12:48 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id 557D6D6837 + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 02:12:45 -0400 (AST) +Received: from 172.16.1.110 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Wed, 16 Nov 2005 01:12:11 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Wed, 16 Nov + 2005 01:11:42 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Wed, 16 Nov + 2005 01:11:41 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Tue, 15 Nov 2005 22:11:39 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "James Mello" <james@haydrian.com>, "William Yu" <wyu@talisys.com>, + pgsql-performance@postgresql.org +Message-ID: <BFA00D9B.13C69%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases ( 5TB) +Thread-Index: AcXqF1J+4GMu4DJdRoSAkms/8lt9bwAADWwwABdEvjs= +In-Reply-To: <775F825B46B551499DC75DC4E92F80AB0E3623@jupiter.ad.haydrian.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 16 Nov 2005 06:11:42.0485 (UTC) + FILETIME=[9D39E450:01C5EA74] +X-WSS-ID: 6F64123131S12018823-01-01 +Content-Type: multipart/alternative; + boundary=B_3214937500_22997028 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[HTML_MESSAGE=0.001, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/266 +X-Sequence-Number: 15523 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3214937500_22997028 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +James, + + +On 11/15/05 11:07 AM, "James Mello" <james@haydrian.com> wrote: + +> Unless there was a way to guarantee consistency, it would be hard at +> best to make this work. Convergence on large data sets across boxes is +> non-trivial, and diffing databases is difficult at best. Unless there +> was some form of automated way to ensure consistency, going 8 ways into +> separate boxes is *very* hard. I do suppose that if you have fancy +> storage (EMC, Hitachi) you could do BCV or Shadow copies. But in terms +> of commodity stuff, I'd have to agree with Merlin. + +It=B9s a matter of good software that handles the distribution / parallel +query optimization / distributed transactions and management features. +Combine that with a gigabit ethernet switch and it works =AD we routinely get +50x speedup over SMP on OLAP / Decision Support workloads. + +Regards, + +- Luke + +--B_3214937500_22997028 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +<HTML> +<HEAD> +<TITLE>Re: [PERFORM] Hardware/OS recommendations for large databases ( 5TB)= + + + +James= +,
+
+
+On 11/15/05 11:07 AM, "James Mello" <james@haydrian.com> wr= +ote:
+
+
Unless there was a way to guarantee consistency, it wou= +ld be hard at
+best to make this work. Convergence on large data sets across boxes is
+non-trivial, and diffing databases is difficult at best. Unless there
+was some form of automated way to ensure consistency, going 8 ways into
+separate boxes is *very* hard. I do suppose that if you have fancy
+storage (EMC, Hitachi) you could do BCV or Shadow copies. But in terms
+of commodity stuff, I'd have to agree with Merlin.
+

+It’s a matter of good software that handles the distribution / parall= +el query optimization / distributed transactions and management features. &n= +bsp;Combine that with a gigabit ethernet switch and it works – we rout= +inely get 50x speedup over SMP on OLAP / Decision Support workloads.
+
+Regards,
+
+- Luke + + + + +--B_3214937500_22997028-- + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 02:57:54 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9499CDB4E7 + for ; + Wed, 16 Nov 2005 02:57:53 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 39475-02 + for ; + Wed, 16 Nov 2005 06:57:52 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from obelix.askesis.nl (laudanum.demon.nl [82.161.125.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 96766DB3C4 + for ; + Wed, 16 Nov 2005 02:57:49 -0400 (AST) +Received: obelix.askesis.nl 172.31.0.1 from 172.31.1.8 172.31.1.8 via HTTP + with MS-WebStorage 6.0.6249 +Received: from Panoramix by obelix.askesis.nl; 16 Nov 2005 07:57:49 +0100 +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +From: Joost Kraaijeveld +To: Luke Lonergan +Cc: Steve Wampler , Dave Cramer , + Pgsql-Performance +In-Reply-To: +References: +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Date: Wed, 16 Nov 2005 07:57:48 +0100 +Message-Id: <1132124268.25582.7.camel@Panoramix> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.3 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/267 +X-Sequence-Number: 15524 + +Hi Luke, + +On Tue, 2005-11-15 at 22:07 -0800, Luke Lonergan wrote: + +> You might update your driver, +I will do that (but I admit that I am not looking forward to it. When I +was young and did not make money with my computer, I liked challenges +like compiling kernels and not being able to boot the computer. Not any +more :-)). + + +> +> WAL on a separate disk, on a separate controller? What is the write +> performance there? +WAL is on a separate disk and a separate controller, write performance: + +jkr@Panoramix:/tmp$ dd if=/dev/zero of=bigfile bs=8k count=1000000 +1000000+0 records in +1000000+0 records out +8192000000 bytes transferred in 166.499230 seconds (49201429 bytes/sec) + +The quest continues... + + +-- +Groeten, + +Joost Kraaijeveld +Askesis B.V. +Molukkenstraat 14 +6524NB Nijmegen +tel: 024-3888063 / 06-51855277 +fax: 024-3608416 +e-mail: J.Kraaijeveld@Askesis.nl +web: www.askesis.nl + + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 06:17:10 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 1EEB0DB8B5 + for ; + Wed, 16 Nov 2005 06:17:09 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 58197-08 + for ; + Wed, 16 Nov 2005 10:17:10 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from obelix.askesis.nl (laudanum.demon.nl [82.161.125.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 1BA38DB73B + for ; + Wed, 16 Nov 2005 06:17:04 -0400 (AST) +Received: obelix.askesis.nl 172.31.0.1 from 172.31.1.8 172.31.1.8 via HTTP + with MS-WebStorage 6.0.6249 +Received: from Panoramix by obelix.askesis.nl; 16 Nov 2005 11:17:06 +0100 +Subject: Re: Performance PG 8.0 on dual opteron / 4GB / 3ware +From: Joost Kraaijeveld +To: Luke Lonergan +Cc: Dave Cramer , + Pgsql-Performance +In-Reply-To: +References: +Content-Type: text/plain; charset=iso-8859-13 +Content-Transfer-Encoding: quoted-printable +Date: Wed, 16 Nov 2005 11:17:05 +0100 +Message-Id: <1132136225.5711.4.camel@Panoramix> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.3 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/268 +X-Sequence-Number: 15525 + +Hi Luke, + + +> It is very important with the 3Ware cards to match the driver to the +> firmware revision. +> So, if you can get your =B4dd bigfile=A1 test to write data at 50MB/s+ +> with a blocksize of 8KB, you should be doing well enough. + +I recompiled my kernel, added the driver and: + +jkr@Panoramix:~$ dmesg | grep 3w +3ware 9000 Storage Controller device driver for Linux v2.26.03.019fw. +scsi4 : 3ware 9000 Storage Controller +3w-9xxx: scsi4: Found a 3ware 9000 Storage Controller at 0xfd8ffc00, +IRQ: 28. +3w-9xxx: scsi4: Firmware FE9X 2.08.00.005, BIOS BE9X 2.03.01.052, Ports: +8. + + +jkr@Panoramix:~/tmp$ dd if=3D/dev/zero of=3Dbigfile bs=3D8k count=3D1000000 +1000000+0 records in +1000000+0 records out +8192000000 bytes transferred in 200.982055 seconds (40759858 bytes/sec) + +Which is an remarkable increase in speed (38.9 MB/sec vs 25.7 MB/sec). + +Thanks for your suggestions. + + +--=20 +Groeten, + +Joost Kraaijeveld +Askesis B.V. +Molukkenstraat 14 +6524NB Nijmegen +tel: 024-3888063 / 06-51855277 +fax: 024-3608416 +e-mail: J.Kraaijeveld@Askesis.nl +web: www.askesis.nl=20 + + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 08:51:55 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id AFD90DB84A + for ; + Wed, 16 Nov 2005 08:51:54 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 99991-05 + for ; + Wed, 16 Nov 2005 12:51:56 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (floppy.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id A10DADAB5A + for ; + Wed, 16 Nov 2005 08:51:50 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id A1D6531058; Wed, 16 Nov 2005 13:51:53 +0100 (MET) +From: William Yu +X-Newsgroups: pgsql.performance +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Wed, 16 Nov 2005 04:51:49 -0800 +Organization: Hub.Org Networking Services +Lines: 20 +Message-ID: +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + + <33c6269f0511152116s4483af82s91c711b1b902da14@mail.gmail.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +User-Agent: Mozilla Thunderbird 1.0 (X11/20041206) +X-Accept-Language: en-us, en +In-Reply-To: <33c6269f0511152116s4483af82s91c711b1b902da14@mail.gmail.com> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/269 +X-Sequence-Number: 15526 + +Alex Turner wrote: +> Not at random access in RAID 10 they aren't, and anyone with their +> head screwed on right is using RAID 10. The 9500S will still beat the +> Areca cards at RAID 10 database access patern. + +The max 256MB onboard for 3ware cards is disappointing though. While +good enough for 95% of cases, there's that 5% that could use a gig or +two of onboard ram for ultrafast updates. For example, I'm specing out +an upgrade to our current data processing server. Instead of the +traditional 6xFast-Server-HDs, we're gonna go for broke and do +32xConsumer-HDs. This will give us mega I/O bandwidth but we're +vulnerable to random access since consumer-grade HDs don't have the RPMs +or the queueing-smarts. This means we're very dependent on the +controller using onboard RAM to do I/O scheduling. 256MB divided over +4/6/8 drives -- OK. 256MB divided over 32 drives -- ugh, the HD's +buffers are bigger than the RAM alotted to it. + +At least this is how it seems it would work from thinking through all +the factors. Unfortunately, I haven't found anybody else who has gone +this route and reported their results so I guess we're the guinea pig. + +From pgsql-performance-owner@postgresql.org Wed Nov 16 09:09:06 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5CF1EDB8D3 + for ; + Wed, 16 Nov 2005 09:08:55 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 02619-09 + for ; + Wed, 16 Nov 2005 13:08:57 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (floppy.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 445BEDA387 + for ; + Wed, 16 Nov 2005 09:08:52 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id D404831058; Wed, 16 Nov 2005 14:08:55 +0100 (MET) +From: William Yu +X-Newsgroups: pgsql.performance +Subject: Re: Hardware/OS recommendations for large databases ( 5TB) +Date: Wed, 16 Nov 2005 05:08:50 -0800 +Organization: Hub.Org Networking Services +Lines: 31 +Message-ID: +References: <775F825B46B551499DC75DC4E92F80AB0E3623@jupiter.ad.haydrian.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +User-Agent: Mozilla Thunderbird 1.0 (X11/20041206) +X-Accept-Language: en-us, en +In-Reply-To: <775F825B46B551499DC75DC4E92F80AB0E3623@jupiter.ad.haydrian.com> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/270 +X-Sequence-Number: 15527 + +James Mello wrote: +> Unless there was a way to guarantee consistency, it would be hard at +> best to make this work. Convergence on large data sets across boxes is +> non-trivial, and diffing databases is difficult at best. Unless there +> was some form of automated way to ensure consistency, going 8 ways into +> separate boxes is *very* hard. I do suppose that if you have fancy +> storage (EMC, Hitachi) you could do BCV or Shadow copies. But in terms +> of commodity stuff, I'd have to agree with Merlin. + +If you're talking about data consistency, I don't see why that's an +issue in a bulk-load/read-only setup. Either bulk load on 1 server and +then do a file copy to all the others -- or simultaneously bulk load on +all servers. + +If you're talking about consistency in directly queries to the +appropriate servers, I agree that's a more complicated issue but not +unsurmountable. If you don't use persistent connections, you can +probably get pretty good routing using DNS -- monitor servers by looking +at top/iostat/memory info/etc and continually change the DNS zonemaps to +direct traffic to less busy servers. (I use this method for our global +load balancers -- pretty easy to script via Perl/Python/etc.) Mind you +since you need a Dual Processor motherboard anyways to get PCI-X, that +means every machine would be a 2xDual Core so there's enough CPU power +to handle the cases where 2 or 3 queries get sent to the same server +back-to-back. Of course, I/O would take a hit in this case -- but I/O +would take a hit in every case on a single 16-core mega system. + +If use persistent connections, it'll definitely require extra +programming beyond simple scripting. Take one of the opensource projects +like PgPool or SQLRelay and alter it so it monitors all servers to see +what server is least busy before passing a query on. + +From pgsql-performance-owner@postgresql.org Wed Nov 16 09:57:27 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6F4BDDB849 + for ; + Wed, 16 Nov 2005 09:57:26 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 10778-06 + for ; + Wed, 16 Nov 2005 13:57:27 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 7F518DB889 + for ; + Wed, 16 Nov 2005 09:57:22 -0400 (AST) +Received: from nmd.esds.den.wayport.net (nmd.esds.den.wayport.net + [64.134.13.30]) + by svr2.postgresql.org (Postfix) with ESMTP id 4DFF0F0BBF + for ; + Wed, 16 Nov 2005 13:57:25 +0000 (GMT) +Received: from nmd.esds.den.wayport.net (localhost [[UNIX: localhost]]) + by nmd.esds.den.wayport.net (8.12.10/8.12.10) with ESMTP id + jAGDvCNZ024054; Wed, 16 Nov 2005 06:57:13 -0700 +Message-ID: <437B3B18.1040509@commandprompt.com> +Date: Wed, 16 Nov 2005 05:58:48 -0800 +From: "Joshua D. Drake" +User-Agent: Thunderbird 1.5 (Windows/20051025) +MIME-Version: 1.0 +To: Alex Turner +Cc: Luke Lonergan , + Adam Weisberg , pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> +In-Reply-To: <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/271 +X-Sequence-Number: 15528 + + +>> I agree - you can get a very good one from www.acmemicro.com or +>> www.rackable.com with 8x 400GB SATA disks and the new 3Ware 9550SX SATA +>> RAID controller for about $6K with two Opteron 272 CPUs and 8GB of RAM +>> on a Tyan 2882 motherboard. We get about 400MB/s sustained disk read +>> performance on these (with tuning) on Linux using the xfs filesystem, +>> which is one of the most critical factors for large databases. +>> +>> +> +> Spend a fortune on dual core CPUs and then buy crappy disks... I bet +> for most applications this system will be IO bound, and you will see a +> nice lot of drive failures in the first year of operation with +> consumer grade drives. +> +There is nothing wrong with using SATA disks and they perform very well. +The catch is, make sure +you have a battery back up on the raid controller. + +> Spend your money on better Disks, and don't bother with Dual Core IMHO +> unless you can prove the need for it. +> +The reason you want the dual core cpus is that PostgreSQL can only +execute 1 query per cpu +at a time, so the application will see a big boost in overall +transactional velocity if you push two +dual-core cpus into the machine. + + +Joshua D. Drake + + +> Alex +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 3: Have you checked our extensive FAQ? +> +> http://www.postgresql.org/docs/faq +> + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 09:59:09 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 7AD8FDB8FB + for ; + Wed, 16 Nov 2005 09:59:07 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 11189-08 + for ; + Wed, 16 Nov 2005 13:59:09 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 2BE32DB8EA + for ; + Wed, 16 Nov 2005 09:59:04 -0400 (AST) +Received: from smtpauth10.mail.atl.earthlink.net + (smtpauth10.mail.atl.earthlink.net [209.86.89.70]) + by svr2.postgresql.org (Postfix) with ESMTP id 2AB82F0BBD + for ; + Wed, 16 Nov 2005 13:59:07 +0000 (GMT) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; + d=earthlink.net; + b=itG9/+4GQowvpvtI8SHLjpOvaSPHM3hbgFztei1AQRc7WNYB50VzARLGwVaKuHKt; + h=Received:Message-Id:X-Mailer:Date:To:From:Subject:In-Reply-To:References:Mime-Version:Content-Type:X-ELNK-Trace:X-Originating-IP; +Received: from [70.22.226.16] (helo=ron-6d52adff2a6.earthlink.net) + by smtpauth10.mail.atl.earthlink.net with asmtp (Exim 4.34) + id 1EcNoV-0005aE-RD; Wed, 16 Nov 2005 08:59:04 -0500 +Message-Id: <6.2.5.6.0.20051116083943.01be0b98@earthlink.net> +X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6 +Date: Wed, 16 Nov 2005 08:58:56 -0500 +To: Alex Turner , pgsql-performance@postgresql.org +From: Ron +Subject: Re: Hardware/OS recommendations for large databases +In-Reply-To: <33c6269f0511152116s4483af82s91c711b1b902da14@mail.gmail.co + m> +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + + <33c6269f0511152116s4483af82s91c711b1b902da14@mail.gmail.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset="us-ascii"; format=flowed +X-ELNK-Trace: + acd68a6551193be5d780f4a490ca69563f9fea00a6dd62bc0a86edbe321ae9a36470654d9361db80350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c +X-Originating-IP: 70.22.226.16 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.479 required=5 tests=[DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.479 +X-Spam-Level: +X-Archive-Number: 200511/272 +X-Sequence-Number: 15529 + +Got some hard numbers to back your statement up? IME, the Areca +1160's with >= 1GB of cache beat any other commodity RAID +controller. This seems to be in agreement with at least one +independent testing source: + +http://print.tweakers.net/?reviews/557 + +RAID HW from Xyratex, Engino, or Dot Hill will _destroy_ any +commodity HW solution, but their price point is considerably higher. + +...on another note, I completely agree with the poster who says we +need more cache on RAID controllers. We should all be beating on the +RAID HW manufacturers to use standard DIMMs for their caches and to +provide 2 standard DIMM slots in their full height cards (allowing +for up to 8GB of cache using 2 4GB DIMMs as of this writing). + +It should also be noted that 64 drive chassis' are going to become +possible once 2.5" 10Krpm SATA II and FC HDs become the standard next +year (48's are the TOTL now). We need controller technology to keep up. + +Ron + +At 12:16 AM 11/16/2005, Alex Turner wrote: +>Not at random access in RAID 10 they aren't, and anyone with their +>head screwed on right is using RAID 10. The 9500S will still beat the +>Areca cards at RAID 10 database access patern. +> +>Alex. +> +>On 11/15/05, Dave Cramer wrote: +> > Luke, +> > +> > Have you tried the areca cards, they are slightly faster yet. +> > +> > Dave +> > +> > On 15-Nov-05, at 7:09 AM, Luke Lonergan wrote: +> > +> > +> > +> > +> > +> > I agree - you can get a very good one from www.acmemicro.com or +> > +> > www.rackable.com with 8x 400GB SATA disks and the new 3Ware 9550SX SATA +> > +> > RAID controller for about $6K with two Opteron 272 CPUs and 8GB of RAM +> > +> > on a Tyan 2882 motherboard. We get about 400MB/s sustained disk read +> > +> > performance on these (with tuning) on Linux using the xfs filesystem, +> > +> > which is one of the most critical factors for large databases. +> > +> > +> > +> > +> > Note that you want to have your DBMS use all of the CPU and disk channel +> > +> > bandwidth you have on each query, which takes a parallel database like +> > +> > Bizgres MPP to achieve. +> > +> > +> > +> > +> > Regards, +> > +> +>---------------------------(end of broadcast)--------------------------- +>TIP 2: Don't 'kill -9' the postmaster + + + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 10:13:31 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 51EAFDB878 + for ; + Wed, 16 Nov 2005 10:13:30 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 13861-04 + for ; + Wed, 16 Nov 2005 14:13:33 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.advfn.com (mail.advfn.com [212.161.99.149]) + by svr1.postgresql.org (Postfix) with ESMTP id 9CA1ADB851 + for ; + Wed, 16 Nov 2005 10:13:27 -0400 (AST) +Received: from [192.168.0.155] (gw.advfn.com [213.86.19.101]) + by mail.advfn.com (Postfix) with ESMTP id 864B79E840; + Wed, 16 Nov 2005 14:13:28 +0000 (GMT) +In-Reply-To: +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + + <33c6269f0511152116s4483af82s91c711b1b902da14@mail.gmail.com> + +Mime-Version: 1.0 (Apple Message framework v734) +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: <41AD9695-69AC-4677-AEBD-9D9E21BD8DCF@advfn.com> +Cc: pgsql-performance@postgresql.org +Content-Transfer-Encoding: 7bit +From: Alex Stapleton +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Wed, 16 Nov 2005 14:13:26 +0000 +To: William Yu +X-Mailer: Apple Mail (2.734) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=-4.3 required=5 tests=[RCVD_IN_BSP_TRUSTED=-4.3] +X-Spam-Score: -4.3 +X-Spam-Level: +X-Archive-Number: 200511/273 +X-Sequence-Number: 15530 + +On 16 Nov 2005, at 12:51, William Yu wrote: + +> Alex Turner wrote: +> +>> Not at random access in RAID 10 they aren't, and anyone with their +>> head screwed on right is using RAID 10. The 9500S will still beat +>> the +>> Areca cards at RAID 10 database access patern. +>> +> +> The max 256MB onboard for 3ware cards is disappointing though. +> While good enough for 95% of cases, there's that 5% that could use +> a gig or two of onboard ram for ultrafast updates. For example, I'm +> specing out an upgrade to our current data processing server. +> Instead of the traditional 6xFast-Server-HDs, we're gonna go for +> broke and do 32xConsumer-HDs. This will give us mega I/O bandwidth +> but we're vulnerable to random access since consumer-grade HDs +> don't have the RPMs or the queueing-smarts. This means we're very +> dependent on the controller using onboard RAM to do I/O scheduling. +> 256MB divided over 4/6/8 drives -- OK. 256MB divided over 32 drives +> -- ugh, the HD's buffers are bigger than the RAM alotted to it. +> +> At least this is how it seems it would work from thinking through +> all the factors. Unfortunately, I haven't found anybody else who +> has gone this route and reported their results so I guess we're the +> guinea pig. +> + +Your going to have to factor in the increased failure rate in your +cost measurements, including any downtime or performance degradation +whilst rebuilding parts of your RAID array. It depends on how long +your planning for this system to be operational as well of course. + +Pick two: Fast, cheap, reliable. + +From pgsql-performance-owner@postgresql.org Wed Nov 16 10:29:51 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 14419DB892 + for ; + Wed, 16 Nov 2005 10:29:51 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14867-09 + for ; + Wed, 16 Nov 2005 14:29:53 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from noao.edu (noao.edu [140.252.1.54]) + by svr1.postgresql.org (Postfix) with ESMTP id C64B5DB851 + for ; + Wed, 16 Nov 2005 10:29:47 -0400 (AST) +X-TFF-CGPSA-Version: 1.4f1 +X-TFF-CGPSA-Filter: Scanned +Received: from weaver.tuc.noao.edu ([140.252.14.8] verified) + by noao.edu (CommuniGate Pro SMTP 5.0.1) + with ESMTPS id 21669031; Wed, 16 Nov 2005 07:29:46 -0700 +Received: from [127.0.0.1] (localhost.localdomain [127.0.0.1]) + by weaver.tuc.noao.edu (8.13.1/8.13.1) with ESMTP id jAGETi6O028973; + Wed, 16 Nov 2005 07:29:45 -0700 +Message-ID: <437B4258.8050507@noao.edu> +Date: Wed, 16 Nov 2005 07:29:44 -0700 +From: Steve Wampler +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: "Joshua D. Drake" +CC: Alex Turner , Luke Lonergan , + Adam Weisberg , pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <437B3B18.1040509@commandprompt.com> +In-Reply-To: <437B3B18.1040509@commandprompt.com> +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/274 +X-Sequence-Number: 15531 + +Joshua D. Drake wrote: +> The reason you want the dual core cpus is that PostgreSQL can only +> execute 1 query per cpu at a time,... + +Is that true? I knew that PG only used one cpu per query, but how +does PG know how many CPUs there are to limit the number of queries? + +-- +Steve Wampler -- swampler@noao.edu +The gods that smiled on your birth are now laughing out loud. + +From pgsql-performance-owner@postgresql.org Wed Nov 16 10:35:23 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 14806DB892 + for ; + Wed, 16 Nov 2005 10:35:22 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 17051-05 + for ; + Wed, 16 Nov 2005 14:35:24 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 166CFD6D16 + for ; + Wed, 16 Nov 2005 10:35:18 -0400 (AST) +Received: from toad.mtbrook.bozemanpass.com (toad.mtbrook.bozemanpass.com + [69.145.82.195]) + by svr2.postgresql.org (Postfix) with ESMTP id 534BCF0C44 + for ; + Wed, 16 Nov 2005 14:35:22 +0000 (GMT) +Received: from [69.145.82.253] (unknown [69.145.82.253]) + by toad.mtbrook.bozemanpass.com (Postfix) with ESMTP id 263A11102E6; + Wed, 16 Nov 2005 06:35:20 -0800 (PST) +Message-ID: <437B43AB.7050104@boreham.org> +Date: Wed, 16 Nov 2005 07:35:23 -0700 +From: David Boreham +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Steve Wampler +Cc: "Joshua D. Drake" , Alex Turner , + Luke Lonergan , + Adam Weisberg , pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <437B3B18.1040509@commandprompt.com> <437B4258.8050507@noao.edu> +In-Reply-To: <437B4258.8050507@noao.edu> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/275 +X-Sequence-Number: 15532 + +Steve Wampler wrote: + +>Joshua D. Drake wrote: +> +> +>>The reason you want the dual core cpus is that PostgreSQL can only +>>execute 1 query per cpu at a time,... +>> +>> +> +>Is that true? I knew that PG only used one cpu per query, but how +>does PG know how many CPUs there are to limit the number of queries? +> +> +> +He means only one query can be executing on each cpu at any particular +instant. + + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 10:38:02 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 81988DB84A + for ; + Wed, 16 Nov 2005 10:38:01 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 17620-03 + for ; + Wed, 16 Nov 2005 14:38:04 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (floppy.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 3C31EDB28E + for ; + Wed, 16 Nov 2005 10:37:58 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id 63F5831058; Wed, 16 Nov 2005 15:38:02 +0100 (MET) +From: William Yu +X-Newsgroups: pgsql.performance +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Wed, 16 Nov 2005 06:37:48 -0800 +Organization: Hub.Org Networking Services +Lines: 11 +Message-ID: +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + + <33c6269f0511152116s4483af82s91c711b1b902da14@mail.gmail.com> + + <41AD9695-69AC-4677-AEBD-9D9E21BD8DCF@advfn.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +User-Agent: Mozilla Thunderbird 1.0 (X11/20041206) +X-Accept-Language: en-us, en +In-Reply-To: <41AD9695-69AC-4677-AEBD-9D9E21BD8DCF@advfn.com> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/276 +X-Sequence-Number: 15533 + +Alex Stapleton wrote: +> Your going to have to factor in the increased failure rate in your cost +> measurements, including any downtime or performance degradation whilst +> rebuilding parts of your RAID array. It depends on how long your +> planning for this system to be operational as well of course. + +If we go 32xRAID10, rebuild time should be the same as rebuild time in a +4xRAID10 system. Only the hard drive that was replaced needs rebuild -- +not the entire array. + +And yes, definitely need a bunch of drives lying around as spares. + +From pgsql-performance-owner@postgresql.org Wed Nov 16 10:40:25 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 480D2DB887 + for ; + Wed, 16 Nov 2005 10:38:52 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 17307-05 + for ; + Wed, 16 Nov 2005 14:38:55 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from noao.edu (noao.edu [140.252.1.54]) + by svr1.postgresql.org (Postfix) with ESMTP id 9CDB5DB84A + for ; + Wed, 16 Nov 2005 10:38:49 -0400 (AST) +X-TFF-CGPSA-Version: 1.4f1 +X-TFF-CGPSA-Filter: Scanned +Received: from weaver.tuc.noao.edu ([140.252.14.8] verified) + by noao.edu (CommuniGate Pro SMTP 5.0.1) + with ESMTPS id 21669179; Wed, 16 Nov 2005 07:38:53 -0700 +Received: from [127.0.0.1] (localhost.localdomain [127.0.0.1]) + by weaver.tuc.noao.edu (8.13.1/8.13.1) with ESMTP id jAGEcquE029170; + Wed, 16 Nov 2005 07:38:52 -0700 +Message-ID: <437B447C.7050508@noao.edu> +Date: Wed, 16 Nov 2005 07:38:52 -0700 +From: Steve Wampler +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: David Boreham +CC: "Joshua D. Drake" , Alex Turner , + Luke Lonergan , + Adam Weisberg , pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <437B3B18.1040509@commandprompt.com> + <437B4258.8050507@noao.edu> <437B43AB.7050104@boreham.org> +In-Reply-To: <437B43AB.7050104@boreham.org> +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/277 +X-Sequence-Number: 15534 + +David Boreham wrote: +> Steve Wampler wrote: +> +>> Joshua D. Drake wrote: +>> +>> +>>> The reason you want the dual core cpus is that PostgreSQL can only +>>> execute 1 query per cpu at a time,... +>>> +>> +>> +>> Is that true? I knew that PG only used one cpu per query, but how +>> does PG know how many CPUs there are to limit the number of queries? +>> +>> +>> +> He means only one query can be executing on each cpu at any particular +> instant. + +Got it - the cpu is only acting on one query in any instant but may be +switching between many 'simultaneous' queries. PG isn't really involved +in the decision. That makes sense. + +-- +Steve Wampler -- swampler@noao.edu +The gods that smiled on your birth are now laughing out loud. + +From pgsql-performance-owner@postgresql.org Wed Nov 16 10:51:26 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 24D98DB9B7 + for ; + Wed, 16 Nov 2005 10:51:25 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 18837-05 + for ; + Wed, 16 Nov 2005 14:51:28 +0000 (GMT) +X-Greylist: delayed 00:16:05.685679 by SQLgrey- +Received: from toad.mtbrook.bozemanpass.com (toad.mtbrook.bozemanpass.com + [69.145.82.195]) + by svr1.postgresql.org (Postfix) with ESMTP id 9007EDB9B5 + for ; + Wed, 16 Nov 2005 10:51:22 -0400 (AST) +Received: from [69.145.82.253] (unknown [69.145.82.253]) + by toad.mtbrook.bozemanpass.com (Postfix) with ESMTP id 6775611027B + for ; + Wed, 16 Nov 2005 06:51:27 -0800 (PST) +Message-ID: <437B4773.1040404@boreham.org> +Date: Wed, 16 Nov 2005 07:51:31 -0700 +From: David Boreham +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <437B3B18.1040509@commandprompt.com> +In-Reply-To: <437B3B18.1040509@commandprompt.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/278 +X-Sequence-Number: 15535 + + >Spend a fortune on dual core CPUs and then buy crappy disks... I bet + >for most applications this system will be IO bound, and you will see a + >nice lot of drive failures in the first year of operation with + >consumer grade drives. + +I guess I've never bought into the vendor story that there are +two reliability grades. Why would they bother making two +different kinds of bearing, motor etc ? Seems like it's more +likely an excuse to justify higher prices. In my experience the +expensive SCSI drives I own break frequently while the cheapo +desktop drives just keep chunking along (modulo certain products +that have a specific known reliability problem). + +I'd expect that a larger number of hotter drives will give a less reliable +system than a smaller number of cooler ones. + + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 11:33:44 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A49A9DBB05 + for ; + Wed, 16 Nov 2005 11:33:43 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 23959-07 + for ; + Wed, 16 Nov 2005 15:33:47 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (floppy.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 78009DBA50 + for ; + Wed, 16 Nov 2005 11:33:40 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id 0916531058; Wed, 16 Nov 2005 16:33:45 +0100 (MET) +From: William Yu +X-Newsgroups: pgsql.performance +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Wed, 16 Nov 2005 07:33:39 -0800 +Organization: Hub.Org Networking Services +Lines: 42 +Message-ID: +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +User-Agent: Mozilla Thunderbird 1.0 (X11/20041206) +X-Accept-Language: en-us, en +In-Reply-To: <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/279 +X-Sequence-Number: 15536 + +Alex Turner wrote: +> Spend a fortune on dual core CPUs and then buy crappy disks... I bet +> for most applications this system will be IO bound, and you will see a +> nice lot of drive failures in the first year of operation with +> consumer grade drives. +> +> Spend your money on better Disks, and don't bother with Dual Core IMHO +> unless you can prove the need for it. + +I would say the opposite -- you always want Dual Core nowadays. DC +Opterons simply give you better bang for the buck than single core +Opterons. Price out a 1xDC system against a 2x1P system -- the 1xDC will +be cheaper. Do the same for 2xDC versus 4x1P, 4xDC versus 8x1P, 8xDC +versus 16x1P, etc. -- DC gets cheaper by wider and wider margins because +those mega-CPU motherboards are astronomically expensive. + +DC also gives you a better upgrade path. Let's say you do testing and +figure 2x246 is the right setup to handle the load. Well instead of +getting 2x1P, use the same 2P motherboard but only populate 1 CPU w/ a +DC/270. Now you have a server that can be upgraded to +80% more CPU by +popping in another DC/270 versus throwing out the entire thing to get a +4x1P setup. + +The only questions would be: +(1) Do you need a SMP server at all? I'd claim yes -- you always need 2+ +cores whether it's DC or 2P to avoid IO interrupts blocking other +processes from running. + +(2) Does a DC system perform better than it's Nx1P cousin? My experience +is yes. Did some rough tests in a drop-in-replacement 1x265 versus 2x244 +and saw about +10% for DC. All the official benchmarks (Spec, Java, SAP, +etc) from AMD/Sun/HP/IBM show DCs outperforming the Nx1P setups. + +(3) Do you need an insane amount of memory? Well here's the case where +the more expensive motherboard will serve you better since each CPU slot +has its own bank of memory. Spend more money on memory, get cheaper +single-core CPUs. + +Of course, this doesn't apply if you are an Intel/Dell-only shop. Xeon +DCs, while cheaper than their corresponding single-core SMPs, don't have +the same performance profile of Opteron DCs. Basically, you're paying a +bit extra so your server can generate a ton more heat. + +From pgsql-performance-owner@postgresql.org Wed Nov 16 11:41:18 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 7D49ADBB65 + for ; + Wed, 16 Nov 2005 11:41:17 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 24984-04 + for ; + Wed, 16 Nov 2005 15:41:21 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (floppy.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 4732FDBB14 + for ; + Wed, 16 Nov 2005 11:41:14 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id 3EC4631058; Wed, 16 Nov 2005 16:41:19 +0100 (MET) +From: William Yu +X-Newsgroups: pgsql.performance +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Wed, 16 Nov 2005 07:41:10 -0800 +Organization: Hub.Org Networking Services +Lines: 25 +Message-ID: +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <437B3B18.1040509@commandprompt.com> <437B4773.1040404@boreham.org> +Mime-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +User-Agent: Mozilla Thunderbird 1.0 (X11/20041206) +X-Accept-Language: en-us, en +In-Reply-To: <437B4773.1040404@boreham.org> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/280 +X-Sequence-Number: 15537 + +David Boreham wrote: +> >Spend a fortune on dual core CPUs and then buy crappy disks... I bet +> >for most applications this system will be IO bound, and you will see a +> >nice lot of drive failures in the first year of operation with +> >consumer grade drives. +> +> I guess I've never bought into the vendor story that there are +> two reliability grades. Why would they bother making two +> different kinds of bearing, motor etc ? Seems like it's more +> likely an excuse to justify higher prices. In my experience the +> expensive SCSI drives I own break frequently while the cheapo +> desktop drives just keep chunking along (modulo certain products +> that have a specific known reliability problem). +> +> I'd expect that a larger number of hotter drives will give a less reliable +> system than a smaller number of cooler ones. + +Our SCSI drives have failed maybe a little less than our IDE drives. +Hell, some of the SCSIs even came bad when we bought them. Of course, +the IDE drive failure % is inflated by all the IBM Deathstars we got -- ugh. + +Basically, I've found it's cooling that's most important. Packing the +drives together into really small rackmounts? Good for your density, not +good for the drives. Now we do larger rackmounts -- drives have more +space in between each other plus fans in front and back of the drives. + +From pgsql-performance-owner@postgresql.org Wed Nov 16 15:15:13 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 180BBDB92F + for ; + Wed, 16 Nov 2005 15:15:12 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 51525-02 + for ; + Wed, 16 Nov 2005 19:15:11 +0000 (GMT) +X-Greylist: delayed 03:14:04.361569 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 5BC02DB947 + for ; + Wed, 16 Nov 2005 15:15:09 -0400 (AST) +Received: from outbound0.sv.meer.net (outbound0.sv.meer.net [205.217.152.13]) + by svr2.postgresql.org (Postfix) with ESMTP id 5F24FF0B01 + for ; + Wed, 16 Nov 2005 16:01:03 +0000 (GMT) +Received: from mail.meer.net (mail.meer.net [209.157.152.14]) + by outbound0.sv.meer.net (8.12.10/8.12.6) with ESMTP id jAGFivQs071823; + Wed, 16 Nov 2005 07:44:57 -0800 (PST) + (envelope-from trainor@TRANSBORDER.NET) +Received: from [192.168.2.2] (pool-70-20-217-196.phil.east.verizon.net + [70.20.217.196]) + by mail.meer.net (8.13.3/8.13.3/meer) with ESMTP id jAGFipO9006973; + Wed, 16 Nov 2005 07:44:51 -0800 (PST) + (envelope-from trainor@transborder.net) +In-Reply-To: <437B447C.7050508@noao.edu> +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <437B3B18.1040509@commandprompt.com> + <437B4258.8050507@noao.edu> <437B43AB.7050104@boreham.org> + <437B447C.7050508@noao.edu> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: <2F6294FF-F274-46E8-85D0-461A6FF36653@transborder.net> +Cc: David Boreham , + "Joshua D. Drake" , Alex Turner , + Luke Lonergan , + Adam Weisberg , pgsql-performance@postgresql.org +Content-Transfer-Encoding: 7bit +From: "Douglas J. Trainor" +Subject: OT Re: Hardware/OS recommendations for large databases ( +Date: Wed, 16 Nov 2005 10:45:15 -0500 +To: Steve Wampler +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/293 +X-Sequence-Number: 15550 + + +AMD added quad-core processors to their public roadmap for 2007. + +Beyond 2007, the quad-cores will scale up to 32 sockets!!!!!!!! +(using Direct Connect Architecture 2.0) + +Expect Intel to follow. + + douglas + +On Nov 16, 2005, at 9:38 AM, Steve Wampler wrote: + +> [...] +> +> Got it - the cpu is only acting on one query in any instant but may be +> switching between many 'simultaneous' queries. PG isn't really +> involved +> in the decision. That makes sense. + +From pgsql-performance-owner@postgresql.org Wed Nov 16 11:46:27 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 082C0DBB93 + for ; + Wed, 16 Nov 2005 11:46:24 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 24941-08 + for ; + Wed, 16 Nov 2005 15:46:27 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from hosting.commandprompt.com (128.commandprompt.com + [207.173.200.128]) + by svr1.postgresql.org (Postfix) with ESMTP id D6B39DBB86 + for ; + Wed, 16 Nov 2005 11:46:20 -0400 (AST) +Received: from [10.30.1.41] ([72.16.194.3]) (authenticated bits=0) + by hosting.commandprompt.com (8.13.4/8.13.4) with ESMTP id + jAGFfGtd032572; Wed, 16 Nov 2005 07:41:22 -0800 +Message-ID: <437B54A9.5070104@commandprompt.com> +Date: Wed, 16 Nov 2005 07:47:53 -0800 +From: "Joshua D. Drake" +User-Agent: Thunderbird 1.5 (Windows/20051025) +MIME-Version: 1.0 +To: David Boreham +CC: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <437B3B18.1040509@commandprompt.com> <437B4773.1040404@boreham.org> +In-Reply-To: <437B4773.1040404@boreham.org> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Greylist: Sender succeded SMTP AUTH authentication, not delayed by + milter-greylist-1.6 (hosting.commandprompt.com [192.168.1.101]); + Wed, 16 Nov 2005 07:41:23 -0800 (PST) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/281 +X-Sequence-Number: 15538 + +> +> I guess I've never bought into the vendor story that there are +> two reliability grades. Why would they bother making two +> different kinds of bearing, motor etc ? Seems like it's more +> likely an excuse to justify higher prices. In my experience the +> expensive SCSI drives I own break frequently while the cheapo +> desktop drives just keep chunking along (modulo certain products +> that have a specific known reliability problem). + +I don't know if the reliability grade is true or not but what I can tell +you is that I have scsi drives that are 5+ years old that still work without +issue. + +I have never had an IDE drive last longer than 3 years (when used in +production). + +That being said, so what. That is what raid is for. You loose a drive +and hot swap +it back in. Heck keep a hotspare in the trays. + +Joshua D. Drake + + +> +> I'd expect that a larger number of hotter drives will give a less +> reliable +> system than a smaller number of cooler ones. +> +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 4: Have you searched our list archives? +> +> http://archives.postgresql.org + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 12:00:14 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id F36C0D7D3D + for ; + Wed, 16 Nov 2005 12:00:12 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 26145-08 + for ; + Wed, 16 Nov 2005 16:00:10 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from toad.mtbrook.bozemanpass.com (toad.mtbrook.bozemanpass.com + [69.145.82.195]) + by svr1.postgresql.org (Postfix) with ESMTP id 6E54FDB84A + for ; + Wed, 16 Nov 2005 12:00:09 -0400 (AST) +Received: from [69.145.82.253] (unknown [69.145.82.253]) + by toad.mtbrook.bozemanpass.com (Postfix) with ESMTP id BF8E511027B + for ; + Wed, 16 Nov 2005 08:00:08 -0800 (PST) +Message-ID: <437B578C.4000309@boreham.org> +Date: Wed, 16 Nov 2005 09:00:12 -0700 +From: David Boreham +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <200511161550.jAGFoCY09049@candle.pha.pa.us> +In-Reply-To: <200511161550.jAGFoCY09049@candle.pha.pa.us> +Content-Type: multipart/alternative; + boundary="------------020409050605040700020305" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[AWL=-0.001, + HTML_MESSAGE=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/282 +X-Sequence-Number: 15539 + +This is a multi-part message in MIME format. +--------------020409050605040700020305 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit + + +> +>I suggest you read this on the difference between enterprise/SCSI and +>desktop/IDE drives: +> +> http://www.seagate.com/content/docs/pdf/whitepaper/D2c_More_than_Interface_ATA_vs_SCSI_042003.pdf +> +> +> +This is exactly the kind of vendor propaganda I was talking about +and it proves my point quite well : that there's nothing specific relating +to reliability that is different between SCSI and SATA drives cited in +that paper. +It does have a bunch of FUD such as 'oh yeah we do a lot more +drive characterization during manufacturing'. + + + + +--------------020409050605040700020305 +Content-Type: text/html; charset=ISO-8859-1 +Content-Transfer-Encoding: 7bit + + + + + + + +
+
+ 

+I suggest you read this on the difference between enterprise/SCSI and
+desktop/IDE drives:
+
+	http://www.seagate.com/content/docs/pdf/whitepaper/D2c_More_than_Interface_ATA_vs_SCSI_042003.pdf
+
+
+
+This is exactly the kind of vendor propaganda I was talking about
+and it proves my point quite well : that there's nothing specific +relating
+to reliability that is different between SCSI and SATA drives cited in +that paper.
+It does have a bunch of FUD such as 'oh yeah we do a lot more
+drive characterization during manufacturing'.
+
+
+
+ + + +--------------020409050605040700020305-- + +From pgsql-performance-owner@postgresql.org Wed Nov 16 12:02:09 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id AAEADDB902 + for ; + Wed, 16 Nov 2005 12:02:07 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 28023-03 + for ; + Wed, 16 Nov 2005 16:02:05 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from hosting.commandprompt.com (128.commandprompt.com + [207.173.200.128]) + by svr1.postgresql.org (Postfix) with ESMTP id ED20DDB90A + for ; + Wed, 16 Nov 2005 12:02:04 -0400 (AST) +Received: from [10.30.1.41] ([72.16.194.3]) (authenticated bits=0) + by hosting.commandprompt.com (8.13.4/8.13.4) with ESMTP id + jAGFv0HB000683; Wed, 16 Nov 2005 07:57:03 -0800 +Message-ID: <437B5859.9040805@commandprompt.com> +Date: Wed, 16 Nov 2005 08:03:37 -0800 +From: "Joshua D. Drake" +User-Agent: Thunderbird 1.5 (Windows/20051025) +MIME-Version: 1.0 +To: William Yu +CC: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + +In-Reply-To: +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Greylist: Sender succeded SMTP AUTH authentication, not delayed by + milter-greylist-1.6 (hosting.commandprompt.com [192.168.1.101]); + Wed, 16 Nov 2005 07:57:03 -0800 (PST) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/283 +X-Sequence-Number: 15540 + +> +> The only questions would be: +> (1) Do you need a SMP server at all? I'd claim yes -- you always need +> 2+ cores whether it's DC or 2P to avoid IO interrupts blocking other +> processes from running. + +I would back this up. Even for smaller installations (single raid 1, 1 +gig of ram). Why? Well because many applications are going to be CPU +bound. For example +we have a PHP application that is a CMS. On a single CPU machine, RAID 1 +it takes about 300ms to deliver a single page, point to point. We are +not IO bound. +So what happens is that under reasonable load we are actually waiting +for the CPU to process the code. + +A simple upgrade to an SMP machine literally doubles our performance +because we are still not IO bound. I strongly suggest that everyone use +at least a single dual core because of this experience. + +> +> (3) Do you need an insane amount of memory? Well here's the case where +> the more expensive motherboard will serve you better since each CPU +> slot has its own bank of memory. Spend more money on memory, get +> cheaper single-core CPUs. +Agreed. A lot of times the slowest dual-core is 5x what you actually +need. So get the slowest, and bulk up on memory. If nothing else memory +is cheap today and it might not be tomorrow. + +> Of course, this doesn't apply if you are an Intel/Dell-only shop. Xeon +> DCs, while cheaper than their corresponding single-core SMPs, don't +> have the same performance profile of Opteron DCs. Basically, you're +> paying a bit extra so your server can generate a ton more heat. +> +Well if you are an Intel/Dell shop running PostgreSQL you have bigger +problems ;) + +Sincerely, + +Joshua D. Drake + + + + +> ---------------------------(end of broadcast)--------------------------- +> TIP 6: explain analyze is your friend + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 15:15:14 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 45AF2DB954 + for ; + Wed, 16 Nov 2005 15:15:13 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 51183-04 + for ; + Wed, 16 Nov 2005 19:15:12 +0000 (GMT) +X-Greylist: delayed 03:07:57.559284 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 71EAADB94E + for ; + Wed, 16 Nov 2005 15:15:10 -0400 (AST) +Received: from vadmzmailmx02.bankofamerica.com (vamx02.bankofamerica.com + [171.159.192.79]) + by svr2.postgresql.org (Postfix) with ESMTP id D9774F0B34 + for ; + Wed, 16 Nov 2005 16:07:10 +0000 (GMT) +Received: from vadmzmailmx03.bankofamerica.com ([171.182.200.79]) + by vadmzmailmx02.bankofamerica.com (8.12.11/8.12.11) with ESMTP id + jAGG741I016316 + for ; Wed, 16 Nov 2005 16:07:06 GMT +Received: from memscmpl4. (varchvp01s209.bankofamerica.com [171.177.163.14]) + by vadmzmailmx03.bankofamerica.com (8.12.11/8.12.11) with SMTP id + jAGG6B05030120 + for ; Wed, 16 Nov 2005 16:07:04 GMT +Received: from memmta0303 (171.186.140.81) + by memscmpl4. (Sigaba Gateway v3.6.1) + with ESMTP id 301306555; Wed, 16 Nov 2005 11:07:03 -0500 +Date: Wed, 16 Nov 2005 11:07:00 -0500 +From: "Welty, Richard" +Subject: Re: Hardware/OS recommendations for large databases ( +To: pgsql-performance@postgresql.org +Message-id: <2F769A036C2082469C3A4BF2603694C601E7686E@ex2k.bankofamerica.com> +MIME-version: 1.0 +X-MIMEOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-type: text/plain; charset=iso-8859-1 +Content-transfer-encoding: 7BIT +Content-class: urn:content-classes:message +Thread-topic: [PERFORM] Hardware/OS recommendations for large databases ( +Thread-index: AcXqxMG5kjnh5GXpRB6kEKlNrPmDdQAAuQxA +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +X-OriginalArrivalTime: 16 Nov 2005 16:07:03.0550 (UTC) + FILETIME=[C8A3D9E0:01C5EAC7] +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/294 +X-Sequence-Number: 15551 + +David Boreham wrote: +> I guess I've never bought into the vendor story that there are +> two reliability grades. Why would they bother making two +> different kinds of bearing, motor etc ? Seems like it's more +> likely an excuse to justify higher prices. + +then how to account for the fact that bleeding edge SCSI drives +turn at twice the rpms of bleeding edge consumer drives? + +richard + +From pgsql-performance-owner@postgresql.org Wed Nov 16 13:06:32 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D3079DB8A6 + for ; + Wed, 16 Nov 2005 13:06:29 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 35077-07 + for ; + Wed, 16 Nov 2005 17:06:28 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from koolancexeon.g2switchworks.com (mail.g2switchworks.com + [63.87.162.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 14AB9DB8D6 + for ; + Wed, 16 Nov 2005 13:06:26 -0400 (AST) +Received: mail.g2switchworks.com 10.10.1.8 from 10.10.1.37 10.10.1.37 via HTTP + with MS-WebStorage 6.5.6944 +Received: from state.g2switchworks.com by mail.g2switchworks.com; + 16 Nov 2005 11:06:25 -0600 +Subject: Re: Hardware/OS recommendations for large databases ( +From: Scott Marlowe +To: David Boreham +Cc: pgsql-performance@postgresql.org +In-Reply-To: <437B4773.1040404@boreham.org> +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <437B3B18.1040509@commandprompt.com> <437B4773.1040404@boreham.org> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Message-Id: <1132160785.3582.60.camel@state.g2switchworks.com> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) +Date: Wed, 16 Nov 2005 11:06:25 -0600 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/284 +X-Sequence-Number: 15541 + +On Wed, 2005-11-16 at 08:51, David Boreham wrote: +> >Spend a fortune on dual core CPUs and then buy crappy disks... I bet +> >for most applications this system will be IO bound, and you will see a +> >nice lot of drive failures in the first year of operation with +> >consumer grade drives. +> +> I guess I've never bought into the vendor story that there are +> two reliability grades. Why would they bother making two +> different kinds of bearing, motor etc ? Seems like it's more +> likely an excuse to justify higher prices. In my experience the +> expensive SCSI drives I own break frequently while the cheapo +> desktop drives just keep chunking along (modulo certain products +> that have a specific known reliability problem). +> +> I'd expect that a larger number of hotter drives will give a less reliable +> system than a smaller number of cooler ones. + +My experience has mirrored this. + +Anyone remember back when HP made their SureStore drives? We built 8 +drive RAID arrays to ship to customer sites, pre-filled with data. Not +a single one arrived fully operational. The failure rate on those +drives was something like 60% in the first year, and HP quit making hard +drives because of it. + +Those were SCSI Server class drives, supposedly built to last 5 years. + +OTOH, I remember putting a pair of 60 Gig IDEs into a server that had +lots of ventilation and fans and such, and having no problems +whatsoever. + +There was a big commercial EMC style array in the hosting center at the +same place that had something like a 16 wide by 16 tall array of IDE +drives for storing pdf / tiff stuff on it, and we had at least one +failure a month in it. Of course, that's 256 drives, so you're gonna +have failures, and it was configured with a spare on every other row or +some such. We just had a big box of hard drives and it was smart enough +to rebuild automagically when you put a new one in, so the maintenance +wasn't really that bad. The performance was quite impressive too. + +From pgsql-performance-owner@postgresql.org Wed Nov 16 13:12:24 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 1C1C7DB935 + for ; + Wed, 16 Nov 2005 13:08:41 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 36295-03 + for ; + Wed, 16 Nov 2005 17:08:39 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.204]) + by svr1.postgresql.org (Postfix) with ESMTP id D29F4DB90E + for ; + Wed, 16 Nov 2005 13:08:37 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id 57so1478324wri + for ; + Wed, 16 Nov 2005 09:08:37 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=U3plebiRJeEgplRPZjVhy8l+/pjZtiSrR4CPf1UQzRbJWQ7u1XBVecOpQ/kA7CgRbMQKN19IVp+bZI9Ze+51o+OUnsa9u7dwoeX1uds4u7XmvxRGonKXLbWqK+tqbwLAcmT5lvuS2loWSwSmHxQIEe+uiK7oPHYyjUDYR4G7Xsk= +Received: by 10.54.99.2 with SMTP id w2mr6042637wrb; + Wed, 16 Nov 2005 09:08:37 -0800 (PST) +Received: by 10.54.82.5 with HTTP; Wed, 16 Nov 2005 09:08:37 -0800 (PST) +Message-ID: <33c6269f0511160908s5c432ee2r82f78598b8f5d036@mail.gmail.com> +Date: Wed, 16 Nov 2005 12:08:37 -0500 +From: Alex Turner +To: Ron +Subject: Re: Hardware/OS recommendations for large databases +Cc: pgsql-performance@postgresql.org +In-Reply-To: <6.2.5.6.0.20051116083943.01be0b98@earthlink.net> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + + <33c6269f0511152116s4483af82s91c711b1b902da14@mail.gmail.com> + <6.2.5.6.0.20051116083943.01be0b98@earthlink.net> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/286 +X-Sequence-Number: 15543 + +Yes - that very benchmark shows that for a MySQL Datadrive in RAID 10, +the 3ware controllers beat the Areca card. + +Alex. + +On 11/16/05, Ron wrote: +> Got some hard numbers to back your statement up? IME, the Areca +> 1160's with >=3D 1GB of cache beat any other commodity RAID +> controller. This seems to be in agreement with at least one +> independent testing source: +> +> http://print.tweakers.net/?reviews/557 +> +> RAID HW from Xyratex, Engino, or Dot Hill will _destroy_ any +> commodity HW solution, but their price point is considerably higher. +> +> ...on another note, I completely agree with the poster who says we +> need more cache on RAID controllers. We should all be beating on the +> RAID HW manufacturers to use standard DIMMs for their caches and to +> provide 2 standard DIMM slots in their full height cards (allowing +> for up to 8GB of cache using 2 4GB DIMMs as of this writing). +> +> It should also be noted that 64 drive chassis' are going to become +> possible once 2.5" 10Krpm SATA II and FC HDs become the standard next +> year (48's are the TOTL now). We need controller technology to keep up. +> +> Ron +> +> At 12:16 AM 11/16/2005, Alex Turner wrote: +> >Not at random access in RAID 10 they aren't, and anyone with their +> >head screwed on right is using RAID 10. The 9500S will still beat the +> >Areca cards at RAID 10 database access patern. +> > +> >Alex. +> > +> >On 11/15/05, Dave Cramer wrote: +> > > Luke, +> > > +> > > Have you tried the areca cards, they are slightly faster yet. +> > > +> > > Dave +> > > +> > > On 15-Nov-05, at 7:09 AM, Luke Lonergan wrote: +> > > +> > > +> > > +> > > +> > > +> > > I agree - you can get a very good one from www.acmemicro.com or +> > > +> > > www.rackable.com with 8x 400GB SATA disks and the new 3Ware 9550SX SA= +TA +> > > +> > > RAID controller for about $6K with two Opteron 272 CPUs and 8GB of RA= +M +> > > +> > > on a Tyan 2882 motherboard. We get about 400MB/s sustained disk read +> > > +> > > performance on these (with tuning) on Linux using the xfs filesystem, +> > > +> > > which is one of the most critical factors for large databases. +> > > +> > > +> > > +> > > +> > > Note that you want to have your DBMS use all of the CPU and disk chan= +nel +> > > +> > > bandwidth you have on each query, which takes a parallel database lik= +e +> > > +> > > Bizgres MPP to achieve. +> > > +> > > +> > > +> > > +> > > Regards, +> > > +> > +> >---------------------------(end of broadcast)--------------------------- +> >TIP 2: Don't 'kill -9' the postmaster +> +> +> +> + +From pgsql-performance-owner@postgresql.org Wed Nov 16 13:09:45 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 98ED7DB945 + for ; + Wed, 16 Nov 2005 13:09:41 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 36233-04 + for ; + Wed, 16 Nov 2005 17:09:40 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from koolancexeon.g2switchworks.com (mail.g2switchworks.com + [63.87.162.25]) + by svr1.postgresql.org (Postfix) with ESMTP id EFF5ADB93D + for ; + Wed, 16 Nov 2005 13:09:38 -0400 (AST) +Received: mail.g2switchworks.com 10.10.1.8 from 10.10.1.37 10.10.1.37 via HTTP + with MS-WebStorage 6.5.6944 +Received: from state.g2switchworks.com by mail.g2switchworks.com; + 16 Nov 2005 11:09:38 -0600 +Subject: Re: Hardware/OS recommendations for large databases ( +From: Scott Marlowe +To: William Yu +Cc: pgsql-performance@postgresql.org +In-Reply-To: +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Message-Id: <1132160978.3582.64.camel@state.g2switchworks.com> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) +Date: Wed, 16 Nov 2005 11:09:38 -0600 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/285 +X-Sequence-Number: 15542 + +On Wed, 2005-11-16 at 09:33, William Yu wrote: +> Alex Turner wrote: +> > Spend a fortune on dual core CPUs and then buy crappy disks... I bet +> > for most applications this system will be IO bound, and you will see a +> > nice lot of drive failures in the first year of operation with +> > consumer grade drives. +> > +> > Spend your money on better Disks, and don't bother with Dual Core IMHO +> > unless you can prove the need for it. +> +> I would say the opposite -- you always want Dual Core nowadays. DC +> Opterons simply give you better bang for the buck than single core +> Opterons. Price out a 1xDC system against a 2x1P system -- the 1xDC will +> be cheaper. Do the same for 2xDC versus 4x1P, 4xDC versus 8x1P, 8xDC +> versus 16x1P, etc. -- DC gets cheaper by wider and wider margins because +> those mega-CPU motherboards are astronomically expensive. + +The biggest gain is going from 1 to 2 CPUs (real cpus, like the DC +Opterons or genuine dual CPU mobo, not "hyperthreaded"). Part of the +issue isn't just raw CPU processing power. The second CPU allows the +machine to be more responsive because it doesn't have to context switch +as much. + +While I've seen plenty of single CPU servers start to bog under load +running one big query, the dual CPU machines always seem more than just +twice as snappy under similar loads. + +From pgsql-performance-owner@postgresql.org Wed Nov 16 13:47:57 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 2A294DB75B + for ; + Wed, 16 Nov 2005 13:47:56 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 40677-05 + for ; + Wed, 16 Nov 2005 17:47:54 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id E0BCCDAB82 + for ; + Wed, 16 Nov 2005 13:47:52 -0400 (AST) +Received: from 172.16.1.110 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Wed, 16 Nov 2005 12:47:41 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Wed, 16 Nov + 2005 12:47:28 -0500 +Received: from 67.103.45.218 ([67.103.45.218]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.105]) with Microsoft Exchange Server HTTP-DAV ; Wed, 16 Nov + 2005 12:47:28 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Wed, 16 Nov 2005 09:47:26 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" +To: "Scott Marlowe" , + "William Yu" +cc: pgsql-performance@postgresql.org +Message-ID: +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXq0SzleDDBZmahTU6pSm6FUY2s3wABKFlI +In-Reply-To: <1132160978.3582.64.camel@state.g2switchworks.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 16 Nov 2005 17:47:28.0592 (UTC) + FILETIME=[CFD84D00:01C5EAD5] +X-WSS-ID: 6F65AF2431S12455364-05-01 +Content-Type: multipart/alternative; + boundary=B_3214979246_23519111 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[HTML_MESSAGE=0.001, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/287 +X-Sequence-Number: 15544 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3214979246_23519111 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Scott, + +On 11/16/05 9:09 AM, "Scott Marlowe" wrote: + +> The biggest gain is going from 1 to 2 CPUs (real cpus, like the DC +> Opterons or genuine dual CPU mobo, not "hyperthreaded"). Part of the +> issue isn't just raw CPU processing power. The second CPU allows the +> machine to be more responsive because it doesn't have to context switch +> as much. +>=20 +> While I've seen plenty of single CPU servers start to bog under load +> running one big query, the dual CPU machines always seem more than just +> twice as snappy under similar loads. +>=20 +I agree, 2 CPUs are better than one in most cases. + +The discussion was kicked off by the suggestion to get 8 dual core CPUs to +process a large database with postgres. Say your decision support query +takes 15 minutes to run with one CPU. Add another and it still takes 15 +minutes. Add 15 and the same ... + +OLTP is so different from Business intelligence and Decision Support that +very little of this thread=B9s discussion is relevant IMO. + +The job is to design a system that can process sequential scan as fast as +possible and uses all resources (CPUs, mem, disk channels) on each query. +Sequential scan is 100x more important than random seeks. + +Here are the facts so far: +* Postgres can only use 1 CPU on each query +* Postgres I/O for sequential scan is CPU limited to 110-120 MB/s on the +fastest modern CPUs +* Postgres disk-based sort speed is 1/10 or more slower than commercial +databases and memory doesn=B9t improve it (much) + +These are the conclusions that follow about decision support / BI system +architecture for normal Postgres: +* I/O hardware with more than 110MB/s of read bandwidth is not useful +* More than 1 CPU is not useful +* More RAM than a nominal amount for small table caching is not useful + +In other words, big SMP doesn=B9t address the problem at all. By contrast, +having all CPUs on multiple machines, or even on a big SMP with lots of I/O +channels, solves all of the above issues. + +Regards, + +- Luke + +--B_3214979246_23519111 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + + + +Re: [PERFORM] Hardware/OS recommendations for large databases (</TIT= +LE> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Scott= +,<BR> +<BR> +On 11/16/05 9:09 AM, "Scott Marlowe" <smarlowe@g2switchworks.c= +om> wrote:<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>The biggest gain is going from 1 to 2 CPUs (real cpus, = +like the DC<BR> +Opterons or genuine dual CPU mobo, not "hyperthreaded").  Pa= +rt of the<BR> +issue isn't just raw CPU processing power.  The second CPU allows the<= +BR> +machine to be more responsive because it doesn't have to context switch<BR> +as much.<BR> +<BR> +While I've seen plenty of single CPU servers start to bog under load<BR> +running one big query, the dual CPU machines always seem more than just<BR> +twice as snappy under similar loads.<BR> +<BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'>I agree, 2 CPUs are better than one in most cases.<BR> +<BR> +The discussion was kicked off by the suggestion to get 8 dual core CPUs to = +process a large database with postgres.  Say your decision support quer= +y takes 15 minutes to run with one CPU.  Add another and it still takes= + 15 minutes.  Add 15 and the same ...<BR> +<BR> +OLTP is <B>so</B> different from Business intelligence and Decision Support= + that very little of this thread’s discussion is relevant IMO.<BR> +<BR> +The job is to design a system that can process sequential scan as fast as p= +ossible and uses all resources (CPUs, mem, disk channels) on each query. &nb= +sp;Sequential scan is 100x more important than random seeks.<BR> +<BR> +Here are the facts so far:<BR> +</SPAN></FONT><UL><LI><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'f= +ont-size:14.0px'>Postgres can only use 1 CPU on each query +</SPAN></FONT><LI><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-= +size:14.0px'>Postgres I/O for sequential scan is CPU limited to 110-120 MB/s= + on the fastest modern CPUs +</SPAN></FONT><LI><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-= +size:14.0px'>Postgres disk-based sort speed is 1/10 or more slower than comm= +ercial databases and memory doesn’t improve it (much)<BR> +</SPAN></FONT></UL><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font= +-size:14.0px'><BR> +These are the conclusions that follow about decision support / BI system ar= +chitecture for normal Postgres:<BR> +</SPAN></FONT><UL><LI><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'f= +ont-size:14.0px'>I/O hardware with more than 110MB/s of read bandwidth is no= +t useful=20 +</SPAN></FONT><LI><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-= +size:14.0px'>More than 1 CPU is not useful +</SPAN></FONT><LI><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-= +size:14.0px'>More RAM than a nominal amount for small table caching is not u= +seful<BR> +</SPAN></FONT></UL><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font= +-size:14.0px'><BR> +In other words, big SMP doesn’t address the problem at all.  By = +contrast, having all CPUs on multiple machines, or even on a big SMP with lo= +ts of I/O channels, solves all of the above issues.<BR> +<BR> +Regards,<BR> +<BR> +- Luke </SPAN></FONT> +</BODY> +</HTML> + + +--B_3214979246_23519111-- + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 13:49:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D4A27DB927 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 13:49:46 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 39244-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 17:49:45 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id E3C56DB92D + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 13:49:43 -0400 (AST) +Received: from 172.16.1.112 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Wed, 16 Nov 2005 12:49:41 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Wed, 16 Nov + 2005 12:49:31 -0500 +Received: from 67.103.45.218 ([67.103.45.218]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.105]) with Microsoft Exchange Server HTTP-DAV ; Wed, 16 Nov + 2005 12:49:30 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Wed, 16 Nov 2005 09:49:28 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Scott Marlowe" <smarlowe@g2switchworks.com>, + "William Yu" <wyu@talisys.com> +cc: pgsql-performance@postgresql.org +Message-ID: <BFA0B128.13D50%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXq0SzleDDBZmahTU6pSm6FUY2s3wABKFlIAAASLus= +In-Reply-To: <BFA0B0AE.13D4E%llonergan@greenplum.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 16 Nov 2005 17:49:31.0061 (UTC) + FILETIME=[18D79650:01C5EAD6] +X-WSS-ID: 6F65AEBF31S12457262-01-01 +Content-Type: multipart/alternative; + boundary=B_3214979369_23551637 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[HTML_MESSAGE=0.001, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/288 +X-Sequence-Number: 15545 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3214979369_23551637 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Oops, + +Last point should be worded: =B3All CPUs on all machines used by a parallel +database=B2 + +- Luke=20 + + +On 11/16/05 9:47 AM, "Luke Lonergan" <llonergan@greenplum.com> wrote: + +> Scott, +>=20 +> On 11/16/05 9:09 AM, "Scott Marlowe" <smarlowe@g2switchworks.com> wrote: +>=20 +>> The biggest gain is going from 1 to 2 CPUs (real cpus, like the DC +>> Opterons or genuine dual CPU mobo, not "hyperthreaded"). Part of the +>> issue isn't just raw CPU processing power. The second CPU allows the +>> machine to be more responsive because it doesn't have to context switch +>> as much. +>>=20 +>> While I've seen plenty of single CPU servers start to bog under load +>> running one big query, the dual CPU machines always seem more than just +>> twice as snappy under similar loads. +>>=20 +> I agree, 2 CPUs are better than one in most cases. +>=20 +> The discussion was kicked off by the suggestion to get 8 dual core CPUs t= +o +> process a large database with postgres. Say your decision support query = +takes +> 15 minutes to run with one CPU. Add another and it still takes 15 minute= +s. +> Add 15 and the same ... +>=20 +> OLTP is so different from Business intelligence and Decision Support that= + very +> little of this thread=B9s discussion is relevant IMO. +>=20 +> The job is to design a system that can process sequential scan as fast as +> possible and uses all resources (CPUs, mem, disk channels) on each query. +> Sequential scan is 100x more important than random seeks. +>=20 +> Here are the facts so far: +> * Postgres can only use 1 CPU on each query +> * Postgres I/O for sequential scan is CPU limited to 110-120 MB/s on the +> fastest modern CPUs +> * Postgres disk-based sort speed is 1/10 or more slower than commercial +> databases and memory doesn=B9t improve it (much) +>=20 +> These are the conclusions that follow about decision support / BI system +> architecture for normal Postgres: +> * I/O hardware with more than 110MB/s of read bandwidth is not useful +> * More than 1 CPU is not useful +> * More RAM than a nominal amount for small table caching is not useful +>=20 +> In other words, big SMP doesn=B9t address the problem at all. By contrast, +> having all CPUs on multiple machines, or even on a big SMP with lots of I= +/O +> channels, solves all of the above issues. +>=20 +> Regards, +>=20 +- Luke=20 + + +--B_3214979369_23551637 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +<HTML> +<HEAD> +<TITLE>Re: [PERFORM] Hardware/OS recommendations for large databases (</TIT= +LE> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Oops,= +<BR> +<BR> +Last point should be worded: “All CPUs on all machines used by a para= +llel database”<BR> +<BR> +- Luke <BR> +<BR> +<BR> +On 11/16/05 9:47 AM, "Luke Lonergan" <llonergan@greenplum.com&= +gt; wrote:<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>Scott,<BR> +<BR> +On 11/16/05 9:09 AM, "Scott Marlowe" <smarlowe@g2switchworks.c= +om> wrote:<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>The biggest gain is going from 1 to 2 CPUs (real cpus, = +like the DC<BR> +Opterons or genuine dual CPU mobo, not "hyperthreaded").  Pa= +rt of the<BR> +issue isn't just raw CPU processing power.  The second CPU allows the<= +BR> +machine to be more responsive because it doesn't have to context switch<BR> +as much.<BR> +<BR> +While I've seen plenty of single CPU servers start to bog under load<BR> +running one big query, the dual CPU machines always seem more than just<BR> +twice as snappy under similar loads.<BR> +<BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'>I agree, 2 CPUs are better than one in most cases.<BR> +<BR> +The discussion was kicked off by the suggestion to get 8 dual core CPUs to = +process a large database with postgres.  Say your decision support quer= +y takes 15 minutes to run with one CPU.  Add another and it still takes= + 15 minutes.  Add 15 and the same ...<BR> +<BR> +OLTP is <B>so</B> different from Business intelligence and Decision Support= + that very little of this thread’s discussion is relevant IMO.<BR> +<BR> +The job is to design a system that can process sequential scan as fast as p= +ossible and uses all resources (CPUs, mem, disk channels) on each query. &nb= +sp;Sequential scan is 100x more important than random seeks.<BR> +<BR> +Here are the facts so far:<BR> +</SPAN></FONT><UL><LI><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'f= +ont-size:14.0px'>Postgres can only use 1 CPU on each query=20 +</SPAN></FONT><LI><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-= +size:14.0px'>Postgres I/O for sequential scan is CPU limited to 110-120 MB/s= + on the fastest modern CPUs=20 +</SPAN></FONT><LI><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-= +size:14.0px'>Postgres disk-based sort speed is 1/10 or more slower than comm= +ercial databases and memory doesn’t improve it (much)<BR> +</SPAN></FONT></UL><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font= +-size:14.0px'><BR> +These are the conclusions that follow about decision support / BI system ar= +chitecture for normal Postgres:<BR> +</SPAN></FONT><UL><LI><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'f= +ont-size:14.0px'>I/O hardware with more than 110MB/s of read bandwidth is no= +t useful=20 +</SPAN></FONT><LI><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-= +size:14.0px'>More than 1 CPU is not useful=20 +</SPAN></FONT><LI><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-= +size:14.0px'>More RAM than a nominal amount for small table caching is not u= +seful<BR> +</SPAN></FONT></UL><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font= +-size:14.0px'><BR> +In other words, big SMP doesn’t address the problem at all.  By = +contrast, having all CPUs on multiple machines, or even on a big SMP with lo= +ts of I/O channels, solves all of the above issues.<BR> +<BR> +Regards,<BR> +<BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'>- Luke <BR> +</SPAN></FONT> +</BODY> +</HTML> + + +--B_3214979369_23551637-- + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 13:54:38 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 06314DB930 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 13:54:38 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 40409-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 17:54:36 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from koolancexeon.g2switchworks.com (mail.g2switchworks.com + [63.87.162.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 61B8EDB92E + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 13:54:34 -0400 (AST) +Received: mail.g2switchworks.com 10.10.1.8 from 10.10.1.37 10.10.1.37 via HTTP + with MS-WebStorage 6.5.6944 +Received: from state.g2switchworks.com by mail.g2switchworks.com; + 16 Nov 2005 11:54:34 -0600 +Subject: Re: Hardware/OS recommendations for large databases ( +From: Scott Marlowe <smarlowe@g2switchworks.com> +To: Luke Lonergan <llonergan@greenplum.com> +Cc: William Yu <wyu@talisys.com>, pgsql-performance@postgresql.org +In-Reply-To: <BFA0B0AE.13D4E%llonergan@greenplum.com> +References: <BFA0B0AE.13D4E%llonergan@greenplum.com> +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: quoted-printable +Message-Id: <1132163674.3582.81.camel@state.g2switchworks.com> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) +Date: Wed, 16 Nov 2005 11:54:34 -0600 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/289 +X-Sequence-Number: 15546 + +On Wed, 2005-11-16 at 11:47, Luke Lonergan wrote: +> Scott, + +Some cutting for clarity... I agree on the OLTP versus OLAP +discussion. =20 + +> Here are the facts so far: +> * Postgres can only use 1 CPU on each query +> * Postgres I/O for sequential scan is CPU limited to 110-120 +> MB/s on the fastest modern CPUs +> * Postgres disk-based sort speed is 1/10 or more slower than +> commercial databases and memory doesn=E2=80=99t improve it (much) + +But PostgreSQL only spills to disk if the data set won't fit into the +amount of memory allocated by working_mem / sort_mem. And for most +Business analysis stuff, this can be quite large, and you can even crank +it up for a single query. =20 + +I've written reports that were horrifically slow, hitting the disk and +all, and I upped sort_mem to hundreds of megabytes until it fit into +memory, and suddenly, a slow query is running factors faster than +before. + +Or did you mean something else by "disk base sort speed"??? + +From pgsql-performance-owner@postgresql.org Wed Nov 16 14:51:29 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CAC53DBA5E + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 14:51:27 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 47324-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 18:51:27 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from xproxy.gmail.com (xproxy.gmail.com [66.249.82.193]) + by svr1.postgresql.org (Postfix) with ESMTP id F2CAEDBA5B + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 14:51:24 -0400 (AST) +Received: by xproxy.gmail.com with SMTP id i30so1732300wxd + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 10:51:25 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:reply-to:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=m5/kr0Fm57JAQ6s3cWuk0qqiJX5zvgX9Qcb1oFKpOsu6Zlj6UQEBP6YvkJ78xusaR4nxvfFqBUs7kCnaCsk8rU+pvWHAl++EThgXC4fot4ew9fIKXMXiW063OXp009BPUZXhNuUyNMFHXg5AvjHjWKPMn2OnALhHPMYl+IfMong= +Received: by 10.70.60.17 with SMTP id i17mr4174899wxa; + Wed, 16 Nov 2005 10:51:25 -0800 (PST) +Received: by 10.70.126.9 with HTTP; Wed, 16 Nov 2005 10:51:25 -0800 (PST) +Message-ID: <f3c0b4080511161051t514b1bd0o8ebe0f5dab6b591b@mail.gmail.com> +Date: Wed, 16 Nov 2005 12:51:25 -0600 +From: Matthew Nuzum <mattnuzum@gmail.com> +Reply-To: newz@bearfruit.org +To: David Boreham <david_list@boreham.org> +Subject: Re: Hardware/OS recommendations for large databases ( +Cc: pgsql-performance@postgresql.org +In-Reply-To: <437B4773.1040404@boreham.org> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <437B3B18.1040509@commandprompt.com> <437B4773.1040404@boreham.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/290 +X-Sequence-Number: 15547 + +On 11/16/05, David Boreham <david_list@boreham.org> wrote: +> >Spend a fortune on dual core CPUs and then buy crappy disks... I bet +> >for most applications this system will be IO bound, and you will see a +> >nice lot of drive failures in the first year of operation with +> >consumer grade drives. +> +> I guess I've never bought into the vendor story that there are +> two reliability grades. Why would they bother making two +> different kinds of bearing, motor etc ? Seems like it's more +> likely an excuse to justify higher prices. In my experience the +> expensive SCSI drives I own break frequently while the cheapo +> desktop drives just keep chunking along (modulo certain products +> that have a specific known reliability problem). +> +> I'd expect that a larger number of hotter drives will give a less reliabl= +e +> system than a smaller number of cooler ones. + +Of all the SCSI and IDE drives I've used, and I've used a lot, there +is a definite difference in quality. The SCSI drives primarily use +higher quality components that are intended to last longer under 24/7 +work loads. I've taken several SCSI and IDE drives apart and you can +tell from the guts that the SCSI drives are built with sturdier +components. + +I haven't gotten my hands on the Raptor line of ATA drives yet, but +I've heard they share this in common with the SCSI drives - they are +built with components made to be used day and night for years straight +without ending. + +That doesn't mean they will last longer than IDE drives, that just +means they've been designed to withstand higher amounts of heat and +sustained activity. I've got some IDE drives that have lasted years++ +and I've got some IDE drives that have lasted months. However, my SCSI +drives I've had over the years all lasted longer than the server they +were installed in. + +I will say that in the last 10 years, the MTBF of IDE/ATA drives has +improved dramatically, so I regularly use them in servers, however I +have also shifted my ideology so that a server should be replaced +after 3 years, where before I aimed for 5. + +It seems to me that the least reliable components in servers these +days are the fans. + +-- +Matthew Nuzum +www.bearfruit.org + +From pgsql-performance-owner@postgresql.org Wed Nov 16 14:52:08 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 13154DBA75 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 14:52:07 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 48805-01-2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 18:52:06 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from cassarossa.samfundet.no (cassarossa.samfundet.no + [129.241.93.19]) + by svr1.postgresql.org (Postfix) with ESMTP id 1AD6EDBA71 + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 14:52:03 -0400 (AST) +Received: from trofast.ipv6.sesse.net ([2001:700:300:dc03:20e:cff:fe36:a766] + helo=trofast.sesse.net) + by cassarossa.samfundet.no with esmtp (Exim 4.50) id 1EcSO0-0000tl-UB + for pgsql-performance@postgresql.org; Wed, 16 Nov 2005 19:52:02 +0100 +Received: from sesse by trofast.sesse.net with local (Exim 3.36 #1 (Debian)) + id 1EcSNe-0005xF-00 + for <pgsql-performance@postgresql.org>; Wed, 16 Nov 2005 19:51:38 +0100 +Date: Wed, 16 Nov 2005 19:51:38 +0100 +From: "Steinar H. Gunderson" <sgunderson@bigfoot.com> +To: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +Message-ID: <20051116185138.GA22831@uio.no> +Mail-Followup-To: pgsql-performance@postgresql.org +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <437B3B18.1040509@commandprompt.com> <437B4773.1040404@boreham.org> + <1132160785.3582.60.camel@state.g2switchworks.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=utf-8 +Content-Disposition: inline +In-Reply-To: <1132160785.3582.60.camel@state.g2switchworks.com> +X-Operating-System: Linux 2.6.14 on a i686 +X-Message-Flag: Outlook? --> http://www.mozilla.org/products/thunderbird/ +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/291 +X-Sequence-Number: 15548 + +On Wed, Nov 16, 2005 at 11:06:25AM -0600, Scott Marlowe wrote: +> There was a big commercial EMC style array in the hosting center at the +> same place that had something like a 16 wide by 16 tall array of IDE +> drives for storing pdf / tiff stuff on it, and we had at least one +> failure a month in it. Of course, that's 256 drives, so you're gonna +> have failures, and it was configured with a spare on every other row or +> some such. We just had a big box of hard drives and it was smart enough +> to rebuild automagically when you put a new one in, so the maintenance +> wasn't really that bad. The performance was quite impressive too. + +If you have a cool SAN, it alerts you and removes all data off a disk +_before_ it starts giving hard failures :-) + +/* Steinar */ +-- +Homepage: http://www.sesse.net/ + +From pgsql-performance-owner@postgresql.org Wed Nov 16 15:03:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B3531DB932 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 15:03:48 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 49534-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 19:03:48 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from xproxy.gmail.com (xproxy.gmail.com [66.249.82.201]) + by svr1.postgresql.org (Postfix) with ESMTP id 1C01CDB925 + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 15:03:45 -0400 (AST) +Received: by xproxy.gmail.com with SMTP id i30so1734894wxd + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 11:03:46 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:reply-to:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=bXuaSXVU2AfFouEiKRoOUCJHXAGyR3LCUHn5NIWhm8XbzneNfungoaoTTRQG+L+6uZSCARsTuzRX2sBpesqHhHC3iGJZfPqGp5ExE5UbWyrkvk9Bd1ZMSgiacHJ++K22pSNqYCqTKiIINa4KUb8zk2feQo7r62smmmoZ1/yuq60= +Received: by 10.70.54.15 with SMTP id c15mr4179022wxa; + Wed, 16 Nov 2005 11:03:46 -0800 (PST) +Received: by 10.70.126.9 with HTTP; Wed, 16 Nov 2005 11:03:46 -0800 (PST) +Message-ID: <f3c0b4080511161103j7677939bldf1c55b137ce9741@mail.gmail.com> +Date: Wed, 16 Nov 2005 13:03:46 -0600 +From: Matthew Nuzum <mattnuzum@gmail.com> +Reply-To: newz@bearfruit.org +To: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +In-Reply-To: <20051116185138.GA22831@uio.no> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <437B3B18.1040509@commandprompt.com> <437B4773.1040404@boreham.org> + <1132160785.3582.60.camel@state.g2switchworks.com> + <20051116185138.GA22831@uio.no> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.666 required=5 tests=[AWL=-0.666, + RCVD_IN_BL_SPAMCOP_NET=1.332] +X-Spam-Score: 0.666 +X-Spam-Level: +X-Archive-Number: 200511/292 +X-Sequence-Number: 15549 + +On 11/16/05, Steinar H. Gunderson <sgunderson@bigfoot.com> wrote: +> If you have a cool SAN, it alerts you and removes all data off a disk +> _before_ it starts giving hard failures :-) +> +> /* Steinar */ +> -- +> Homepage: http://www.sesse.net/ + +Good point. I have avoided data loss *twice* this year by using SMART +hard drive monitoring software. + +I can't tell you how good it feels to replace a drive that is about to +die, as compared to restoring data because a drive died. +-- +Matthew Nuzum +www.bearfruit.org + +From pgsql-performance-owner@postgresql.org Wed Nov 16 15:24:42 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 936A9D7763 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 15:24:40 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 52007-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 19:24:40 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from yertle.kcilink.com (yertle.kcilink.com [65.205.34.180]) + by svr1.postgresql.org (Postfix) with ESMTP id C04B4D709D + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 15:24:37 -0400 (AST) +Received: from [192.168.7.103] (host-103.int.kcilink.com [192.168.7.103]) + by yertle.kcilink.com (Postfix) with ESMTP id E4B9BB80A + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 14:24:38 -0500 (EST) +Mime-Version: 1.0 (Apple Message framework v746.2) +In-Reply-To: <b41c75520511150028o553e6bb5j@mail.gmail.com> +References: <1B80C974ABFB23429A403B6667FE84C71066E8@seiumain.SEIU.local> + <b41c75520511150028o553e6bb5j@mail.gmail.com> +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: <D1ABFA1F-FEB0-4E01-BC2E-482535A5DB28@khera.org> +Content-Transfer-Encoding: 7bit +From: Vivek Khera <vivek@khera.org> +Subject: Re: Hardware/OS recommendations for large databases (5TB) +Date: Wed, 16 Nov 2005 14:24:38 -0500 +To: Postgresql Performance <pgsql-performance@postgresql.org> +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/295 +X-Sequence-Number: 15552 + + +On Nov 15, 2005, at 3:28 AM, Claus Guttesen wrote: + +> Hardware-wise I'd say dual core opterons. One dual-core-opteron +> performs better than two single-core at the same speed. Tyan makes + +at 5TB data, i'd vote that the application is disk I/O bound, and the +difference in CPU speed at the level of dual opteron vs. dual-core +opteron is not gonna be noticed. + +to maximize disk, try getting a dedicated high-end disk system like +nstor or netapp file servers hooked up to fiber channel, then use a +good high-end fiber channel controller like one from LSI. + +and go with FreeBSD amd64 port. It is *way* fast, especially the +FreeBSD 6.0 disk system. + + +From pgsql-www-owner@postgresql.org Wed Nov 16 16:18:59 2005 +X-Original-To: pgsql-www-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5D88FD87A0; + Wed, 16 Nov 2005 16:00:29 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 37655-03; Wed, 16 Nov 2005 20:00:29 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtp.nildram.co.uk (smtp.nildram.co.uk [195.112.4.54]) + by svr1.postgresql.org (Postfix) with ESMTP id 5466AD860D; + Wed, 16 Nov 2005 16:00:26 -0400 (AST) +Received: from [192.168.0.4] (unknown [84.12.200.148]) + by smtp.nildram.co.uk (Postfix) with ESMTP + id 878AF25336B; Wed, 16 Nov 2005 20:00:23 +0000 (GMT) +Subject: Re: [PERFORM] Help speeding up delete +From: Simon Riggs <simon@2ndquadrant.com> +To: pgsql-www@postgresql.org, Tom Lane <tgl@sss.pgh.pa.us> +Cc: Steve Wampler <swampler@noao.edu>, + Postgres-performance <pgsql-performance@postgresql.org> +In-Reply-To: <4162.1132011763@sss.pgh.pa.us> +References: <43790A99.9050603@noao.edu> <4162.1132011763@sss.pgh.pa.us> +Content-Type: text/plain +Date: Wed, 16 Nov 2005 20:00:06 +0000 +Message-Id: <1132171206.4959.60.camel@localhost.localdomain> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.2 (2.2.2-5) +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/105 +X-Sequence-Number: 8820 + +On Mon, 2005-11-14 at 18:42 -0500, Tom Lane wrote: +> Steve Wampler <swampler@noao.edu> writes: +> > We've got an older system in production (PG 7.2.4). + +> +> Update to 7.4 or later ;-) +> +> Quite seriously, if you're still using 7.2.4 for production purposes +> you could justifiably be accused of negligence. There are three or four +> data-loss-grade bugs fixed in the later 7.2.x releases, not to mention +> security holes; and that was before we abandoned support for 7.2. +> You *really* need to be thinking about an update. + +Perhaps we should put a link on the home page underneath LATEST RELEASEs +saying + 7.2: de-supported + +with a link to a scary note along the lines of the above. + +ISTM that there are still too many people on older releases. + +We probably need an explanation of why we support so many releases (in +comparison to licenced software) and a note that this does not imply the +latest releases are not yet production (in comparison to MySQL or Sybase +who have been in beta for a very long time). + +Best Regards, Simon Riggs + + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 16:09:23 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 3579ED8CA0 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 16:09:22 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 37656-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 20:09:22 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from koolancexeon.g2switchworks.com (mail.g2switchworks.com + [63.87.162.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 761ACD8B2D + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 16:09:19 -0400 (AST) +Received: mail.g2switchworks.com 10.10.1.8 from 10.10.1.37 10.10.1.37 via HTTP + with MS-WebStorage 6.5.6944 +Received: from state.g2switchworks.com by mail.g2switchworks.com; + 16 Nov 2005 14:08:03 -0600 +Subject: Re: Hardware/OS recommendations for large databases ( +From: Scott Marlowe <smarlowe@g2switchworks.com> +To: "Steinar H. Gunderson" <sgunderson@bigfoot.com> +Cc: pgsql-performance@postgresql.org +In-Reply-To: <20051116185138.GA22831@uio.no> +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <437B3B18.1040509@commandprompt.com> <437B4773.1040404@boreham.org> + <1132160785.3582.60.camel@state.g2switchworks.com> + <20051116185138.GA22831@uio.no> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Message-Id: <1132171683.3582.85.camel@state.g2switchworks.com> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) +Date: Wed, 16 Nov 2005 14:08:03 -0600 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/297 +X-Sequence-Number: 15554 + +On Wed, 2005-11-16 at 12:51, Steinar H. Gunderson wrote: +> On Wed, Nov 16, 2005 at 11:06:25AM -0600, Scott Marlowe wrote: +> > There was a big commercial EMC style array in the hosting center at the +> > same place that had something like a 16 wide by 16 tall array of IDE +> > drives for storing pdf / tiff stuff on it, and we had at least one +> > failure a month in it. Of course, that's 256 drives, so you're gonna +> > have failures, and it was configured with a spare on every other row or +> > some such. We just had a big box of hard drives and it was smart enough +> > to rebuild automagically when you put a new one in, so the maintenance +> > wasn't really that bad. The performance was quite impressive too. +> +> If you have a cool SAN, it alerts you and removes all data off a disk +> _before_ it starts giving hard failures :-) + +Yeah, I forget who made the unit we used, but it was pretty much fully +automated. IT was something like a large RAID 5+0 (0+5???) and would +send an alert when a drive died or started getting errors, and the bad +drive's caddy would be flashing read instead of steady green. + +I just remember thinking that I'd never used a drive array that was +taller than I was before that. + +From pgsql-performance-owner@postgresql.org Wed Nov 16 19:25:09 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 18F1ED8930 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 19:25:08 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 64276-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 23:25:10 +0000 (GMT) +X-Greylist: delayed 03:02:46.857118 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 92568D6853 + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 19:25:05 -0400 (AST) +Received: from olive.qinip.net (olive.qinip.net [62.100.30.40]) + by svr2.postgresql.org (Postfix) with ESMTP id C9F8EF0B3E + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 20:22:18 +0000 (GMT) +Received: from [127.0.0.1] (h8441139206.dsl.speedlinq.nl [84.41.139.206]) + by olive.qinip.net (Postfix) with ESMTP id 7D86A180F9; + Wed, 16 Nov 2005 21:22:11 +0100 (MET) +Message-ID: <437B94F9.20306@tweakers.net> +Date: Wed, 16 Nov 2005 21:22:17 +0100 +From: Arjen van der Meijden <acmmailing@tweakers.net> +User-Agent: Thunderbird 1.5 (Windows/20051025) +MIME-Version: 1.0 +To: Steve Wampler <swampler@noao.edu> +Cc: Postgres-performance <pgsql-performance@postgresql.org> +Subject: Re: Help speeding up delete +References: <6BCB9D8A16AC4241919521715F4D8BCE6C7BC4@algol.sollentuna.se> + <4379EE24.8000504@noao.edu> +In-Reply-To: <4379EE24.8000504@noao.edu> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Antivirus: avast! (VPS 0546-3, 16-11-2005), Outbound message +X-Antivirus-Status: Clean +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/306 +X-Sequence-Number: 15563 + +On 15-11-2005 15:18, Steve Wampler wrote: +> Magnus Hagander wrote: +> (This is after putting an index on the (id,name,value) tuple.) That outer seq scan +> is still annoying, but maybe this will be fast enough. +> +> I've passed this on, along with the (strong) recommendation that they +> upgrade PG. + +Have you tried with an index on (name,value) and of course one on id ? + +Best regards, + +Arjen + +From pgsql-performance-owner@postgresql.org Wed Nov 16 16:29:51 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 36D19D8D8F + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 16:29:50 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 40154-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 20:29:49 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from noao.edu (noao.edu [140.252.1.54]) + by svr1.postgresql.org (Postfix) with ESMTP id 547E9D818A + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 16:29:46 -0400 (AST) +X-TFF-CGPSA-Version: 1.4f1 +X-TFF-CGPSA-Filter: Scanned +Received: from weaver.tuc.noao.edu ([140.252.14.8] verified) + by noao.edu (CommuniGate Pro SMTP 5.0.1) + with ESMTPS id 21676021; Wed, 16 Nov 2005 13:29:44 -0700 +Received: from [127.0.0.1] (localhost.localdomain [127.0.0.1]) + by weaver.tuc.noao.edu (8.13.1/8.13.1) with ESMTP id jAGKTiGI025161; + Wed, 16 Nov 2005 13:29:44 -0700 +Message-ID: <437B96B8.2090302@noao.edu> +Date: Wed, 16 Nov 2005 13:29:44 -0700 +From: Steve Wampler <swampler@noao.edu> +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Arjen van der Meijden <acmmailing@tweakers.net> +CC: Postgres-performance <pgsql-performance@postgresql.org> +Subject: Re: Help speeding up delete +References: <6BCB9D8A16AC4241919521715F4D8BCE6C7BC4@algol.sollentuna.se> + <4379EE24.8000504@noao.edu> <437B94F9.20306@tweakers.net> +In-Reply-To: <437B94F9.20306@tweakers.net> +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/298 +X-Sequence-Number: 15555 + +Arjen van der Meijden wrote: +> On 15-11-2005 15:18, Steve Wampler wrote: +> +>> Magnus Hagander wrote: +>> (This is after putting an index on the (id,name,value) tuple.) That +>> outer seq scan +>> is still annoying, but maybe this will be fast enough. +>> +>> I've passed this on, along with the (strong) recommendation that they +>> upgrade PG. +> +> +> Have you tried with an index on (name,value) and of course one on id ? + +Yes, although not with a unique index on (name,value) [possible, but not +so on the just-id index]. Anyway, it turns out the latest incarnation +is 'fast enough' for the user's need, so she's not doing any more with +it until after an upgrade. + + +-- +Steve Wampler -- swampler@noao.edu +The gods that smiled on your birth are now laughing out loud. + +From pgsql-performance-owner@postgresql.org Wed Nov 16 16:57:30 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 124B4D6FF4 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 16:57:29 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 44455-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 20:57:29 +0000 (GMT) +X-Greylist: delayed 06:58:24.754511 by SQLgrey- +Received: from smtpauth08.mail.atl.earthlink.net + (smtpauth08.mail.atl.earthlink.net [209.86.89.68]) + by svr1.postgresql.org (Postfix) with ESMTP id EA752D6853 + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 16:57:25 -0400 (AST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; + d=earthlink.net; + b=IyQVBvmo9g7DS696otlWwMya3P1K7B2wy0x7ctgy8UcItbyoLypGKR7ridMWZWCI; + h=Received:Message-Id:X-Mailer:Date:To:From:Subject:In-Reply-To:References:Mime-Version:Content-Type:X-ELNK-Trace:X-Originating-IP; +Received: from [70.22.226.16] (helo=ron-6d52adff2a6.earthlink.net) + by smtpauth08.mail.atl.earthlink.net with asmtp (Exim 4.34) + id 1EcULM-0001Lq-Tu; Wed, 16 Nov 2005 15:57:25 -0500 +Message-Id: <6.2.5.6.0.20051116154502.01c41f50@earthlink.net> +X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6 +Date: Wed, 16 Nov 2005 15:57:20 -0500 +To: Alex Turner <armtuk@gmail.com>,pgsql-performance@postgresql.org +From: Ron <rjpeace@earthlink.net> +Subject: Re: Hardware/OS recommendations for large databases +In-Reply-To: <33c6269f0511160908s5c432ee2r82f78598b8f5d036@mail.gmail.co + m> +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <B41A9E46-AC4F-4A3A-B383-AB70091745CF@fastcrypt.com> + <33c6269f0511152116s4483af82s91c711b1b902da14@mail.gmail.com> + <6.2.5.6.0.20051116083943.01be0b98@earthlink.net> + <33c6269f0511160908s5c432ee2r82f78598b8f5d036@mail.gmail.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset="us-ascii"; format=flowed +X-ELNK-Trace: + acd68a6551193be5d780f4a490ca69563f9fea00a6dd62bc57020ef3721c0cf8c22e08205296a0c7350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c +X-Originating-IP: 70.22.226.16 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.359 required=5 tests=[AWL=-0.120, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.359 +X-Spam-Level: +X-Archive-Number: 200511/299 +X-Sequence-Number: 15556 + +You _ARE_ kidding right? In what hallucination? + +The performance numbers for the 1GB cache version of the Areca 1160 +are the _grey_ line in the figures, and were added after the original +article was published: + +"Note: Since the original Dutch article was published in late +January, we have finished tests of the 16-port Areca ARC-1160 using +128MB, 512MB and 1GB cache configurations and RAID 5 arrays of up to +12 drives. The ARC-1160 was using the latest 1.35 beta firmware. The +performance graphs have been updated to include the ARC-1160 results. +Discussions of the results have not been updated, however. " + +With 1GB of cache, the 1160's beat everything else in almost all of +the tests they participated in. For the few where they do not win +hands down, the Escalade's (very occasionally) essentially tie. + +These are very easy to read full color graphs where higher is better +and the grey line representing the 1GB 1160's is almost always higher +on the graph than anything else. Granted the Escalades seem to give +them the overall best run for their money, but they still are clearly +second best when looking at all the graphs and the CPU utilization +numbers in aggregate. + +Ron + + + +At 12:08 PM 11/16/2005, Alex Turner wrote: +>Yes - that very benchmark shows that for a MySQL Datadrive in RAID 10, +>the 3ware controllers beat the Areca card. +> +>Alex. +> +>On 11/16/05, Ron <rjpeace@earthlink.net> wrote: +> > Got some hard numbers to back your statement up? IME, the Areca +> > 1160's with >= 1GB of cache beat any other commodity RAID +> > controller. This seems to be in agreement with at least one +> > independent testing source: +> > +> > http://print.tweakers.net/?reviews/557 +> > +> > RAID HW from Xyratex, Engino, or Dot Hill will _destroy_ any +> > commodity HW solution, but their price point is considerably higher. +> > +> > ...on another note, I completely agree with the poster who says we +> > need more cache on RAID controllers. We should all be beating on the +> > RAID HW manufacturers to use standard DIMMs for their caches and to +> > provide 2 standard DIMM slots in their full height cards (allowing +> > for up to 8GB of cache using 2 4GB DIMMs as of this writing). +> > +> > It should also be noted that 64 drive chassis' are going to become +> > possible once 2.5" 10Krpm SATA II and FC HDs become the standard next +> > year (48's are the TOTL now). We need controller technology to keep up. +> > +> > Ron +> > +> > At 12:16 AM 11/16/2005, Alex Turner wrote: +> > >Not at random access in RAID 10 they aren't, and anyone with their +> > >head screwed on right is using RAID 10. The 9500S will still beat the +> > >Areca cards at RAID 10 database access patern. +> > > +> > >Alex. +> > > +> > >On 11/15/05, Dave Cramer <pg@fastcrypt.com> wrote: +> > > > Luke, +> > > > +> > > > Have you tried the areca cards, they are slightly faster yet. +> > > > +> > > > Dave +> > > > +> > > > On 15-Nov-05, at 7:09 AM, Luke Lonergan wrote: +> > > > +> > > > +> > > > +> > > > +> > > > +> > > > I agree - you can get a very good one from www.acmemicro.com or +> > > > +> > > > www.rackable.com with 8x 400GB SATA disks and the new 3Ware 9550SX SATA +> > > > +> > > > RAID controller for about $6K with two Opteron 272 CPUs and 8GB of RAM +> > > > +> > > > on a Tyan 2882 motherboard. We get about 400MB/s sustained disk read +> > > > +> > > > performance on these (with tuning) on Linux using the xfs filesystem, +> > > > +> > > > which is one of the most critical factors for large databases. +> > > > +> > > > +> > > > +> > > > +> > > > Note that you want to have your DBMS use all of the CPU and +> disk channel +> > > > +> > > > bandwidth you have on each query, which takes a parallel database like +> > > > +> > > > Bizgres MPP to achieve. +> > > > +> > > > +> > > > +> > > > +> > > > Regards, +> > > > +> > > +> > >---------------------------(end of broadcast)--------------------------- +> > >TIP 2: Don't 'kill -9' the postmaster +> > +> > +> > +> > + + + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 17:01:57 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 90BAFD6D50 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 17:01:56 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 45249-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 21:01:57 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 0CFFCD6D16 + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 17:01:53 -0400 (AST) +Received: from moonunit2.moonview.localnet (wsip-68-15-5-150.sd.sd.cox.net + [68.15.5.150]) + by svr2.postgresql.org (Postfix) with ESMTP id 858EDF0B58 + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 21:01:55 +0000 (GMT) +Received: from [192.168.0.3] (moonunit3.moonview.localnet [192.168.0.3]) + by moonunit2.moonview.localnet (8.13.1/8.13.1) with ESMTP id + jAGLADiV015144 + for <pgsql-performance@postgresql.org>; Wed, 16 Nov 2005 13:10:13 -0800 +Message-ID: <437B9DA9.2030806@modgraph-usa.com> +Date: Wed, 16 Nov 2005 12:59:21 -0800 +From: "Craig A. James" <cjames@modgraph-usa.com> +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20050716) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +Cc: Pgsql-Performance <pgsql-performance@postgresql.org> +Subject: Perl DBD and an alarming problem +References: <BF9F6C0E.13B4A%llonergan@greenplum.com> + <1132136225.5711.4.camel@Panoramix> +In-Reply-To: <1132136225.5711.4.camel@Panoramix> +Content-Type: text/plain; charset=ISO-8859-13; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.189 required=5 tests=[MISSING_HEADERS=0.189] +X-Spam-Score: 0.189 +X-Spam-Level: +X-Archive-Number: 200511/300 +X-Sequence-Number: 15557 + +I am mystified by the behavior of "alarm" in conjunction with Postgres/perl/DBD. Here is roughly what I'm doing: + + eval { + local $SIG{ALRM} = sub {die("Timeout");}; + $time = gettimeofday; + alarm 20; + $sth = $dbh->prepare("a query that may take a long time..."); + $sth->execute(); + alarm 0; + }; + if ($@ && $@ =~ /Timeout/) { + my $elapsed = gettimeofday - $time; + print "Timed out after $elapsed seconds"; + } + +Now the mystery: It works, but it hardly matters what time I use for the alarm call, the actual alarm event always happens at 26 seconds. I can set "alarm 1" or "alarm 20", and it almost always hits right at 26 seconds. + +Now if I increase alarm to anything in the range of about 25-60 seconds, the actual alarm arrives somewhere around the 90 second mark. It seems as though there are "windows of opportunity" for the alarm, and it is ignored until those "windows" arrive. + +Anyone have a clue what's going on and/or how I can fix it? + +A secondary question: It appears that $sth->cancel() is not implemented in the Pg DBD module. Is that true? + +Thanks, +Craig + +From pgsql-performance-owner@postgresql.org Wed Nov 16 17:36:15 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id EA829D6FCB + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 17:36:11 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 54651-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 21:36:12 +0000 (GMT) +X-Greylist: delayed 00:32:32.360955 by SQLgrey- +Received: from mail0.rawbw.com (mail0.rawbw.com [198.144.192.41]) + by svr1.postgresql.org (Postfix) with ESMTP id 3CACBD6D16 + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 17:36:09 -0400 (AST) +Received: (from www@localhost) + by mail0.rawbw.com (8.11.6p2/8.11.6) id jAGL3bE15914 + for pgsql-performance@postgresql.org; + Wed, 16 Nov 2005 13:03:37 -0800 (PST) +Received: from cybs-gw.ic3.com (cybs-gw.ic3.com [66.185.177.10]) + by webmail.rawbw.com (IMP) with HTTP + for <mudfoot@shell.rawbw.com>; Wed, 16 Nov 2005 13:03:37 -0800 +Message-ID: <1132175017.437b9ea9e33e2@webmail.rawbw.com> +Date: Wed, 16 Nov 2005 13:03:37 -0800 +From: mudfoot@rawbw.com +To: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <437B3B18.1040509@commandprompt.com> <437B4773.1040404@boreham.org> + <1132160785.3582.60.camel@state.g2switchworks.com> + <20051116185138.GA22831@uio.no> + <1132171683.3582.85.camel@state.g2switchworks.com> +In-Reply-To: <1132171683.3582.85.camel@state.g2switchworks.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: 8bit +User-Agent: Internet Messaging Program (IMP) 3.2.1 +X-Originating-IP: 66.185.177.10 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.55 required=5 tests=[NO_REAL_NAME=0.55] +X-Spam-Score: 0.55 +X-Spam-Level: +X-Archive-Number: 200511/303 +X-Sequence-Number: 15560 + +Yeah those big disks arrays are real sweet. + +One day last week I was in a data center in Arizona when the big LSI/Storagetek +array in the cage next to mine had a hard drive failure. So the alarm shrieked +at like 13225535 decibles continuously for hours. BEEEP BEEEEP BEEEEP BEEEEP. +Of course since this was a colo facility it wasn't staffed on site by the idiots +who own the array. BEEEEP BEEEEEEEP BEEEEEEEP for hours. So I had to stand +next to this thing--only separated by a few feet and a little wire mesh--while +it shrieked for hours until a knuckle-dragger arrived on site to swap the drive. + +Yay. + +So if you're going to get a fancy array (they're worth it if somebody else is +paying) then make sure to *turn off the @#%@#SF'ing audible alarm* if you deploy +it in a colo facility. + +Quoting Scott Marlowe <smarlowe@g2switchworks.com>: + +> On Wed, 2005-11-16 at 12:51, Steinar H. Gunderson wrote: +> > On Wed, Nov 16, 2005 at 11:06:25AM -0600, Scott Marlowe wrote: +> > > There was a big commercial EMC style array in the hosting center at the +> > > same place that had something like a 16 wide by 16 tall array of IDE +> > > drives for storing pdf / tiff stuff on it, and we had at least one +> > > failure a month in it. Of course, that's 256 drives, so you're gonna +> > > have failures, and it was configured with a spare on every other row or +> > > some such. We just had a big box of hard drives and it was smart +> enough +> > > to rebuild automagically when you put a new one in, so the maintenance +> > > wasn't really that bad. The performance was quite impressive too. +> > +> > If you have a cool SAN, it alerts you and removes all data off a disk +> > _before_ it starts giving hard failures :-) +> +> Yeah, I forget who made the unit we used, but it was pretty much fully +> automated. IT was something like a large RAID 5+0 (0+5???) and would +> send an alert when a drive died or started getting errors, and the bad +> drive's caddy would be flashing read instead of steady green. +> +> I just remember thinking that I'd never used a drive array that was +> taller than I was before that. +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 6: explain analyze is your friend +> + + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 17:04:48 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 686A6D6853 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 17:04:47 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 46778-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 21:04:48 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (floppy.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 59E5BD8CA0 + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 17:04:44 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id C8C0731058; Wed, 16 Nov 2005 22:04:45 +0100 (MET) +From: Ron Mayer <rm_pg@cheapcomplexdevices.com> +X-Newsgroups: pgsql.performance +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Wed, 16 Nov 2005 13:08:58 -0800 +Organization: Hub.Org Networking Services +Lines: 42 +Message-ID: <437B9FEA.5010003@cheapcomplexdevices.com> +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <437B3B18.1040509@commandprompt.com> + <437B4773.1040404@boreham.org> <dlfjuk$9n9$1@news.hub.org> +Mime-Version: 1.0 +Content-Type: text/plain; charset=windows-1252; format=flowed +Content-Transfer-Encoding: 8bit +X-Complaints-To: usenet@news.hub.org +To: William Yu <wyu@talisys.com> +User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) +X-Accept-Language: en-us, en +In-Reply-To: <dlfjuk$9n9$1@news.hub.org> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/301 +X-Sequence-Number: 15558 + +William Yu wrote: +> +> Our SCSI drives have failed maybe a little less than our IDE drives. + +Microsoft in their database showcase terraserver project has +had the same experience. They studied multiple configurations +including a SCSI/SAN solution as well as a cluster of SATA boxes. + +They measured a + 6.4% average annual failure rate of their SATA version and a + 5.5% average annual failure rate on their SCSI implementation. + +ftp://ftp.research.microsoft.com/pub/tr/TR-2004-107.pdf + + "We lost 9 drives out of 140 SATA drives on the Web and + Storage Bricks in one year. This is a 6.4% annual failure rate. + In contrast, the Compaq Storageworks SAN and Web servers lost + approximately 32 drives in three years out of a total of 194 + drives.13 This is a 5.5% annual failure rate. + + The failure rates indicate that SCSI drives are more + reliable than SATA. SATA drives are substantially + cheaper than SCSI drives. Because the SATA failure rate + is so close to the SCSI failure rate gives SATA a + substantial return on investment advantage." + +So unless your system is extremely sensitive to single drive +failures, the difference is pretty small. And for the cost +it seems you can buy enough extra spindles of SATA drives to +easily make up for the performance difference. + + +> Basically, I've found it's cooling that's most important. Packing the +> drives together into really small rackmounts? Good for your density, not +> good for the drives. + +Indeed that was their guess for their better-than-expected +life of their SATA drives as well. From the same paper: + + "We were careful about disk cooling � SATA + drives are rarely cooled with the same care that a SCSI + array receives." + +From pgsql-performance-owner@postgresql.org Wed Nov 16 17:21:35 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 1B7FAD87A0 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 17:21:34 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 47471-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 21:21:32 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtpauth06.mail.atl.earthlink.net + (smtpauth06.mail.atl.earthlink.net [209.86.89.66]) + by svr1.postgresql.org (Postfix) with ESMTP id CE71CD7718 + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 17:21:28 -0400 (AST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; + d=earthlink.net; + b=bvgIjQuqKqXUdqZ45KE6Dqeffk01hObKDaZUDmNvlX2YPy0Hsvy+hAgPAmbBDdRv; + h=Received:Message-Id:X-Mailer:Date:To:From:Subject:In-Reply-To:References:Mime-Version:Content-Type:X-ELNK-Trace:X-Originating-IP; +Received: from [70.22.226.16] (helo=ron-6d52adff2a6.earthlink.net) + by smtpauth06.mail.atl.earthlink.net with asmtp (Exim 4.34) + id 1EcUif-0007p6-TG; Wed, 16 Nov 2005 16:21:30 -0500 +Message-Id: <6.2.5.6.0.20051116161052.03d54a70@earthlink.net> +X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6 +Date: Wed, 16 Nov 2005 16:21:25 -0500 +To: Alex Turner <armtuk@gmail.com>,pgsql-performance@postgresql.org +From: Ron <rjpeace@earthlink.net> +Subject: Re: Hardware/OS recommendations for large databases +In-Reply-To: <6.2.5.6.0.20051116154502.01c41f50@earthlink.net> +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <B41A9E46-AC4F-4A3A-B383-AB70091745CF@fastcrypt.com> + <33c6269f0511152116s4483af82s91c711b1b902da14@mail.gmail.com> + <6.2.5.6.0.20051116083943.01be0b98@earthlink.net> + <33c6269f0511160908s5c432ee2r82f78598b8f5d036@mail.gmail.com> + <6.2.5.6.0.20051116154502.01c41f50@earthlink.net> +Mime-Version: 1.0 +Content-Type: text/plain; charset="us-ascii"; format=flowed +X-ELNK-Trace: + acd68a6551193be5d780f4a490ca69563f9fea00a6dd62bcf0cd1e4a07881175fee78a105238f226350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c +X-Originating-IP: 70.22.226.16 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.359 required=5 tests=[AWL=-0.120, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.359 +X-Spam-Level: +X-Archive-Number: 200511/302 +X-Sequence-Number: 15559 + +Amendment: there are graphs where the 1GB Areca 1160's do not do as +well. Given that they are mySQL specific and that similar usage +scenarios not involving mySQL (as well as most of the usage scenarios +involving mySQL; as I said these did not follow the pattern of the +rest of the benchmarks) show the usual pattern of the 1GB 1160's in +1st place or tied for 1st place, it seems reasonable that mySQL has +something to due with the aberrant results in those 2 (IIRC) cases. + +Ron + +At 03:57 PM 11/16/2005, Ron wrote: +>You _ARE_ kidding right? In what hallucination? +> +>The performance numbers for the 1GB cache version of the Areca 1160 +>are the _grey_ line in the figures, and were added after the +>original article was published: +> +>"Note: Since the original Dutch article was published in late +>January, we have finished tests of the 16-port Areca ARC-1160 using +>128MB, 512MB and 1GB cache configurations and RAID 5 arrays of up to +>12 drives. The ARC-1160 was using the latest 1.35 beta firmware. The +>performance graphs have been updated to include the ARC-1160 +>results. Discussions of the results have not been updated, however. " +> +>With 1GB of cache, the 1160's beat everything else in almost all of +>the tests they participated in. For the few where they do not win +>hands down, the Escalade's (very occasionally) essentially tie. +> +>These are very easy to read full color graphs where higher is better +>and the grey line representing the 1GB 1160's is almost always +>higher on the graph than anything else. Granted the Escalades seem +>to give them the overall best run for their money, but they still +>are clearly second best when looking at all the graphs and the CPU +>utilization numbers in aggregate. +> +>Ron +> +> +> +>At 12:08 PM 11/16/2005, Alex Turner wrote: +>>Yes - that very benchmark shows that for a MySQL Datadrive in RAID 10, +>>the 3ware controllers beat the Areca card. +>> +>>Alex. +>> +>>On 11/16/05, Ron <rjpeace@earthlink.net> wrote: +>> > Got some hard numbers to back your statement up? IME, the Areca +>> > 1160's with >= 1GB of cache beat any other commodity RAID +>> > controller. This seems to be in agreement with at least one +>> > independent testing source: +>> > +>> > http://print.tweakers.net/?reviews/557 +>> > +>> > RAID HW from Xyratex, Engino, or Dot Hill will _destroy_ any +>> > commodity HW solution, but their price point is considerably higher. +>> > +>> > ...on another note, I completely agree with the poster who says we +>> > need more cache on RAID controllers. We should all be beating on the +>> > RAID HW manufacturers to use standard DIMMs for their caches and to +>> > provide 2 standard DIMM slots in their full height cards (allowing +>> > for up to 8GB of cache using 2 4GB DIMMs as of this writing). +>> > +>> > It should also be noted that 64 drive chassis' are going to become +>> > possible once 2.5" 10Krpm SATA II and FC HDs become the standard next +>> > year (48's are the TOTL now). We need controller technology to keep up. +>> > +>> > Ron +>> > +>> > At 12:16 AM 11/16/2005, Alex Turner wrote: +>> > >Not at random access in RAID 10 they aren't, and anyone with their +>> > >head screwed on right is using RAID 10. The 9500S will still beat the +>> > >Areca cards at RAID 10 database access patern. +>> > > +>> > >Alex. +>> > > +>> > >On 11/15/05, Dave Cramer <pg@fastcrypt.com> wrote: +>> > > > Luke, +>> > > > +>> > > > Have you tried the areca cards, they are slightly faster yet. +>> > > > +>> > > > Dave +>> > > > +>> > > > On 15-Nov-05, at 7:09 AM, Luke Lonergan wrote: +>> > > > +>> > > > +>> > > > +>> > > > +>> > > > +>> > > > I agree - you can get a very good one from www.acmemicro.com or +>> > > > +>> > > > www.rackable.com with 8x 400GB SATA disks and the new 3Ware +>> 9550SX SATA +>> > > > +>> > > > RAID controller for about $6K with two Opteron 272 CPUs and 8GB of RAM +>> > > > +>> > > > on a Tyan 2882 motherboard. We get about 400MB/s sustained disk read +>> > > > +>> > > > performance on these (with tuning) on Linux using the xfs filesystem, +>> > > > +>> > > > which is one of the most critical factors for large databases. +>> > > > +>> > > > +>> > > > +>> > > > +>> > > > Note that you want to have your DBMS use all of the CPU and +>> disk channel +>> > > > +>> > > > bandwidth you have on each query, which takes a parallel database like +>> > > > +>> > > > Bizgres MPP to achieve. +>> > > > +>> > > > +>> > > > +>> > > > +>> > > > Regards, +>> > > > +>> > > +>> > >---------------------------(end of broadcast)--------------------------- +>> > >TIP 2: Don't 'kill -9' the postmaster +>> > +>> > +>> > +>> > +> +> +> + + + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 17:50:20 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 38596D7061 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 17:50:20 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 55933-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 21:50:21 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from zproxy.gmail.com (zproxy.gmail.com [64.233.162.201]) + by svr1.postgresql.org (Postfix) with ESMTP id A2217D6853 + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 17:50:17 -0400 (AST) +Received: by zproxy.gmail.com with SMTP id z3so1522319nzf + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 13:50:19 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=rCEIW+23z9LTiVtRKoN3nfjvAtYxqcYJaLpCNTL0fUSTSBBJ3eV3RciZ5fT+YcMuzR7VSTMYe4HrgkzeZ2+S+e/9reff5bB4PiBHgDK7TOJ/TRzKG1fJgEJ5A46+D4kR9dH7oryXiKeCSBzMXYl9pPqT4DoFXOw82NZgCcM4gFA= +Received: by 10.64.142.16 with SMTP id p16mr1307149qbd; + Wed, 16 Nov 2005 13:50:19 -0800 (PST) +Received: by 10.65.192.16 with HTTP; Wed, 16 Nov 2005 13:50:19 -0800 (PST) +Message-ID: <b41c75520511161350u3ed6f4b1x@mail.gmail.com> +Date: Wed, 16 Nov 2005 22:50:19 +0100 +From: Claus Guttesen <kometen@gmail.com> +To: Vivek Khera <vivek@khera.org> +Subject: Re: Hardware/OS recommendations for large databases (5TB) +Cc: Postgresql Performance <pgsql-performance@postgresql.org> +In-Reply-To: <D1ABFA1F-FEB0-4E01-BC2E-482535A5DB28@khera.org> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <1B80C974ABFB23429A403B6667FE84C71066E8@seiumain.SEIU.local> + <b41c75520511150028o553e6bb5j@mail.gmail.com> + <D1ABFA1F-FEB0-4E01-BC2E-482535A5DB28@khera.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/304 +X-Sequence-Number: 15561 + +> at 5TB data, i'd vote that the application is disk I/O bound, and the +> difference in CPU speed at the level of dual opteron vs. dual-core +> opteron is not gonna be noticed. +> +> to maximize disk, try getting a dedicated high-end disk system like +> nstor or netapp file servers hooked up to fiber channel, then use a +> good high-end fiber channel controller like one from LSI. +> +> and go with FreeBSD amd64 port. It is *way* fast, especially the +> FreeBSD 6.0 disk system. + +I'm (also) FreeBSD-biased but I'm not shure whether the 5 TB fs will +work so well if tools like fsck are needed. Gvinum could be one option +but I don't have any experience in that area. + +regards +Claus + +From pgsql-performance-owner@postgresql.org Wed Nov 16 18:59:28 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D14E4D88AB + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 18:59:26 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 64017-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 22:59:28 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.clickdiario.com (mail.clickdiario.com [70.85.167.114]) + by svr1.postgresql.org (Postfix) with ESMTP id 4EAE9D6D16 + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 18:59:23 -0400 (AST) +Received: from localhost (localhost [127.0.0.1]) + by mail.clickdiario.com (Postfix) with ESMTP id BF91F10005; + Wed, 16 Nov 2005 17:06:45 -0600 (CST) +Received: from mail.clickdiario.com ([127.0.0.1]) + by localhost (mail.clickdiario.com [127.0.0.1]) (amavisd-new, + port 10024) + with ESMTP id 08481-04; Wed, 16 Nov 2005 17:06:45 -0600 (CST) +Received: by mail.clickdiario.com (Postfix, from userid 5001) + id A583710064; Wed, 16 Nov 2005 17:06:45 -0600 (CST) +Received: from cristian1 (unknown [216.230.131.226]) + by mail.clickdiario.com (Postfix) with ESMTP id 70C6610005; + Wed, 16 Nov 2005 17:06:44 -0600 (CST) +From: "Cristian Prieto" <cristian@clickdiario.com> +To: <pgpool-general@pgfoundry.org>, + <pgsql-performance@postgresql.org> +Subject: PgPool and Postgresql sessions... +Date: Wed, 16 Nov 2005 16:56:42 -0600 +Message-ID: <007601c5eb01$04436ef0$6500a8c0@gt.ClickDiario.local> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="US-ASCII" +Content-Transfer-Encoding: 7bit +X-Mailer: Microsoft Office Outlook 11 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 +Thread-Index: AcXrAQKifZg6wAaXRHeJ1yGHR0sMdw== +X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at example.com +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/305 +X-Sequence-Number: 15562 + +Hi, I just have a little question, does PgPool keeps the same session +between different connections? I say it cuz I have a server with the +following specifications: + +P4 3.2 ghz +80 gig sata drives x 2 +1 gb ram +5 ips +1200 gb bandwidth +100 mbit/s port speed. + +I am running a PgSQL 8.1 server with 100 max connection, pgpool with +num_init_children = 25 and max_pool = 4. I do the same queries all the time +(just a bunch of sps, but they are always the same). Using explain analyze I +get the fact that the sps are using a lot of time the first time they +execute (I guess preparing the plan and the sps I wrote en plpgsql) so I +would like to reuse the session the most possible. I need to serve 10M of +connection per day. Is this possible? (the client is a webapplication, I +repeat again, the queries are always the same). + +Thanks a lot for your help... + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 19:30:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 99749D6FF4 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 19:30:44 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 64772-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 23:30:46 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from biglumber.com (biglumber.com [207.228.252.42]) + by svr1.postgresql.org (Postfix) with SMTP id 65E7FD9177 + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 19:30:41 -0400 (AST) +Received: (qmail 6623 invoked from network); 16 Nov 2005 23:30:44 -0000 +Received: from unknown (HELO localhost) (207.228.252.42) + by 0 with SMTP; 16 Nov 2005 23:30:44 -0000 +From: "Greg Sabino Mullane" <greg@turnstep.com> +To: pgsql-performance@postgresql.org +Subject: Re: Perl DBD and an alarming problem +X-PGP-Key: 2529 DF6A B8F7 9407 E944 45B4 BC9B 9067 1496 4AC8 +X-Request-PGP: + http://www.biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8 +In-Reply-To: <437B9DA9.2030806@modgraph-usa.com> +Date: Wed, 16 Nov 2005 23:30:44 -0000 +X-Mailer: JoyMail 1.48 +Message-ID: <b61d71c1a4056df4bd92b29656c2f16a@biglumber.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/307 +X-Sequence-Number: 15564 + + +-----BEGIN PGP SIGNED MESSAGE----- +Hash: SHA1 + + +> I am mystified by the behavior of "alarm" in conjunction with +> Postgres/perl/DBD. Here is roughly what I'm doing: + +> Anyone have a clue what's going on and/or how I can fix it? + +Not really, but alarm has never worked well (or claimed to) with +DBI. The DBI docs recommend trying out Sys::Sigaction: + +http://search.cpan.org/~lbaxter/Sys-SigAction/ + +> A secondary question: It appears that $sth->cancel() is not +> implemented in the Pg DBD module. Is that true? + +Correct. DBD::Pg does not support asynchronous connections. It's +possible it may in the future, but there has not been much of a +perceived need. Feel free to enter a request on CPAN: + +http://rt.cpan.org/NoAuth/Bugs.html?Dist=DBD-Pg + +There may be another way around it, if you can tell us some more +about what exactly it is you are trying to do. + +- -- +Greg Sabino Mullane greg@turnstep.com +PGP Key: 0x14964AC8 200511161830 +http://biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8 +-----BEGIN PGP SIGNATURE----- + +iD8DBQFDe8ErvJuQZxSWSsgRAoZ6AJ9h6gV5U7PyLDJIqXLpSB6r7NWaaQCdESSR +CdNexfvYvSQjOLkEdPXd26U= +=/W5F +-----END PGP SIGNATURE----- + + + +From pgsql-performance-owner@postgresql.org Wed Nov 16 20:23:52 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id BDDC8D8417 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 16 Nov 2005 20:23:50 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 71478-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 00:23:52 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from tigger.fuhr.org (tigger.fuhr.org [63.214.45.158]) + by svr1.postgresql.org (Postfix) with ESMTP id C3D16D6D16 + for <pgsql-performance@postgresql.org>; + Wed, 16 Nov 2005 20:23:47 -0400 (AST) +Received: from winnie.fuhr.org (winnie.fuhr.org [10.1.0.1]) + by tigger.fuhr.org (8.13.3/8.13.3) with ESMTP id jAH0Njbe048338 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); + Wed, 16 Nov 2005 17:23:48 -0700 (MST) + (envelope-from mfuhr@winnie.fuhr.org) +Received: from winnie.fuhr.org (localhost [127.0.0.1]) + by winnie.fuhr.org (8.13.4/8.13.4) with ESMTP id jAH0NjL4055582; + Wed, 16 Nov 2005 17:23:45 -0700 (MST) + (envelope-from mfuhr@winnie.fuhr.org) +Received: (from mfuhr@localhost) + by winnie.fuhr.org (8.13.4/8.13.4/Submit) id jAH0Njmq055581; + Wed, 16 Nov 2005 17:23:45 -0700 (MST) (envelope-from mfuhr) +Date: Wed, 16 Nov 2005 17:23:45 -0700 +From: Michael Fuhr <mike@fuhr.org> +To: "Craig A. James" <cjames@modgraph-usa.com> +Cc: Pgsql-Performance <pgsql-performance@postgresql.org> +Subject: Re: Perl DBD and an alarming problem +Message-ID: <20051117002344.GA55377@winnie.fuhr.org> +References: <BF9F6C0E.13B4A%llonergan@greenplum.com> + <1132136225.5711.4.camel@Panoramix> + <437B9DA9.2030806@modgraph-usa.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <437B9DA9.2030806@modgraph-usa.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/308 +X-Sequence-Number: 15565 + +On Wed, Nov 16, 2005 at 12:59:21PM -0800, Craig A. James wrote: +> eval { +> local $SIG{ALRM} = sub {die("Timeout");}; +> $time = gettimeofday; +> alarm 20; +> $sth = $dbh->prepare("a query that may take a long time..."); +> $sth->execute(); +> alarm 0; +> }; +> if ($@ && $@ =~ /Timeout/) { +> my $elapsed = gettimeofday - $time; +> print "Timed out after $elapsed seconds"; +> } +> +> Now the mystery: It works, but it hardly matters what time I use for the +> alarm call, the actual alarm event always happens at 26 seconds. I can set +> "alarm 1" or "alarm 20", and it almost always hits right at 26 seconds. + +High-level languages' signal handlers don't always work well with +low-level libraries. I haven't dug into the Perl source code but +I'd guess that since only certain things are safe to do in a signal +handler, Perl's handler simply sets some kind of state that the +interpreter will examine later during normal execution. If you're +using only Perl facilities then that probably happens fairly timely, +but if you're stuck in a low-level library (e.g., libpq) then you +might have to wait until that library returns control to Perl before +Perl recognizes that a signal occurred. + +As an example, if I run code such as yours with alarm(2) and a query +that takes 5 seconds, I see the following in a process trace (from +ktrace/kdump on FreeBSD): + +55395 perl 0.000978 CALL poll(0xbfbfe1b8,0x1,0xffffffff) +55395 perl 1.996629 RET poll -1 errno 4 Interrupted system call +55395 perl 0.000013 PSIG SIGALRM caught handler=0x281be22c mask=0x0 code=0x0 +55395 perl 0.000050 CALL sigprocmask(0x1,0,0x805411c) +55395 perl 0.000005 RET sigprocmask 0 +55395 perl 0.000020 CALL sigreturn(0xbfbfde60) +55395 perl 0.000007 RET sigreturn JUSTRETURN +55395 perl 0.000019 CALL poll(0xbfbfe1b8,0x1,0xffffffff) +55395 perl 3.004065 RET poll 1 +55395 perl 0.000024 CALL recvfrom(0x3,0x81c6000,0x4000,0,0,0) +55395 perl 0.000016 GIO fd 3 read 60 bytes + +The poll() call is interrupted by SIGALRM after 2 seconds but then +it starts again and doesn't return until the query completes after +the remaining 3 seconds. Only sometime later does Perl invoke the +ALRM handler I installed, presumably because it can't do so until +the low-level code returns control to Perl. + +Is there a reason you're using alarm() in the client instead of +setting statement_timeout on the server? + +-- +Michael Fuhr + +From pgsql-performance-owner@postgresql.org Thu Nov 17 02:05:32 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 750F2DB972 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 02:05:26 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 81612-09-4 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 06:05:25 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 3B26DDB908 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 02:05:19 -0400 (AST) +Received: from europa.cosmos.opusvl.com (europa.cosmos.opusvl.com + [213.106.249.125]) + by svr2.postgresql.org (Postfix) with ESMTP id C7597F0AC6 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 01:06:47 +0000 (GMT) +Received: from localhost ([127.0.0.1]) + by europa.cosmos.opusvl.com with esmtp (Exim 4.30) + id 1EcYEd-0002IH-0V + for pgsql-performance@postgresql.org; Thu, 17 Nov 2005 01:06:43 +0000 +Message-ID: <437BD7A2.608@opusvl.com> +Date: Thu, 17 Nov 2005 01:06:42 +0000 +From: Rich Doughty <rich@opusvl.com> +Organization: Opus VL +User-Agent: Mozilla Thunderbird 1.0.2 (X11/20050317) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Pgsql-Performance <pgsql-performance@postgresql.org> +Subject: Strange query plan invloving a view +Content-Type: text/plain; charset=UTF-8; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/311 +X-Sequence-Number: 15568 + +i have the following query involving a view that i really need to optimise: + +SELECT * +FROM + tokens.ta_tokenhist h INNER JOIN + tokens.vw_tokens t ON h.token_id = t.token_id +WHERE + h.sarreport_id = 9 +; + +where vw_tokens is defined as + +CREATE VIEW tokens.vw_tokens AS SELECT + -- too many columns to mention +FROM + tokens.ta_tokens t LEFT JOIN + tokens.ta_tokenhist i ON t.token_id = i.token_id AND + i.status = 'issued' LEFT JOIN + tokens.ta_tokenhist s ON t.token_id = s.token_id AND + s.status = 'sold' LEFT JOIN + tokens.ta_tokenhist r ON t.token_id = r.token_id AND + r.status = 'redeemed' +; + +this gives me the following query plan: + +Merge Join (cost=18276278.45..31793043.16 rows=55727 width=322) + Merge Cond: (("outer".token_id)::integer = "inner"."?column23?") + -> Merge Left Join (cost=18043163.64..31639175.71 rows=4228018 width=76) + Merge Cond: (("outer".token_id)::integer = "inner"."?column3?") + -> Merge Left Join (cost=13649584.94..27194793.37 rows=4228018 width=48) + Merge Cond: (("outer".token_id)::integer = "inner"."?column3?") + -> Merge Left Join (cost=7179372.62..20653326.29 rows=4228018 width=44) + Merge Cond: (("outer".token_id)::integer = "inner"."?column3?") + -> Index Scan using ta_tokens_pkey on ta_tokens t (cost=0.00..13400398.89 rows=4053805 width=27) + -> Sort (cost=7179372.62..7189942.67 rows=4228018 width=21) + Sort Key: (i.token_id)::integer + -> Index Scan using fkx_tokenhist__status on ta_tokenhist i (cost=0.00..6315961.47 rows=4228018 width=21) + Index Cond: ((status)::text = 'issued'::text) + -> Sort (cost=6470212.32..6479909.69 rows=3878949 width=8) + Sort Key: (s.token_id)::integer + -> Index Scan using fkx_tokenhist__status on ta_tokenhist s (cost=0.00..5794509.99 rows=3878949 width=8) + Index Cond: ((status)::text = 'sold'::text) + -> Sort (cost=4393578.70..4400008.00 rows=2571718 width=32) + Sort Key: (r.token_id)::integer + -> Index Scan using fkx_tokenhist__status on ta_tokenhist r (cost=0.00..3841724.02 rows=2571718 width=32) + Index Cond: ((status)::text = 'redeemed'::text) + -> Sort (cost=233114.81..233248.38 rows=53430 width=246) + Sort Key: (h.token_id)::integer + -> Index Scan using fkx_tokenhist__sarreports on ta_tokenhist h (cost=0.00..213909.12 rows=53430 width=246) + Index Cond: ((sarreport_id)::integer = 9) + + +However, the following query (which i believe should be equivalent) + +SELECT * +FROM + tokens.ta_tokenhist h INNER JOIN + tokens.ta_tokens t ON h.token_id = t.token_id LEFT JOIN + tokens.ta_tokenhist i ON t.token_id = i.token_id AND + i.status = 'issued' LEFT JOIN + tokens.ta_tokenhist s ON t.token_id = s.token_id AND + s.status = 'sold' LEFT JOIN + tokens.ta_tokenhist r ON t.token_id = r.token_id AND + r.status = 'redeemed' +WHERE + h.sarreport_id = 9 +; + +gives the following query plan: + + Nested Loop Left Join (cost=0.00..3475785.52 rows=55727 width=1011) + -> Nested Loop Left Join (cost=0.00..2474425.17 rows=55727 width=765) + -> Nested Loop Left Join (cost=0.00..1472368.23 rows=55727 width=519) + -> Nested Loop (cost=0.00..511614.87 rows=53430 width=273) + -> Index Scan using fkx_tokenhist__sarreports on ta_tokenhist h (cost=0.00..213909.12 rows=53430 width=246) + Index Cond: ((sarreport_id)::integer = 9) + -> Index Scan using ta_tokens_pkey on ta_tokens t (cost=0.00..5.56 rows=1 width=27) + Index Cond: (("outer".token_id)::integer = (t.token_id)::integer) + -> Index Scan using fkx_tokenhist__tokens on ta_tokenhist i (cost=0.00..17.96 rows=2 width=246) + Index Cond: (("outer".token_id)::integer = (i.token_id)::integer) + Filter: ((status)::text = 'issued'::text) + -> Index Scan using fkx_tokenhist__tokens on ta_tokenhist s (cost=0.00..17.96 rows=2 width=246) + Index Cond: (("outer".token_id)::integer = (s.token_id)::integer) + Filter: ((status)::text = 'sold'::text) + -> Index Scan using fkx_tokenhist__tokens on ta_tokenhist r (cost=0.00..17.96 rows=1 width=246) + Index Cond: (("outer".token_id)::integer = (r.token_id)::integer) + Filter: ((status)::text = 'redeemed'::text) + +This query returns a lot quicker than the plan would suggest, as the +planner is over-estimating the amount of rows where +((sarreport_id)::integer = 9). it thinks there are 53430 when in fact +there are only 7 (despite a vacuum and analyse). + +Can anyone give me any suggestions? are the index stats the cause of +my problem, or is it the rewrite of the query? + +Cheers + + +Version: PostgreSQL 8.0.3 on i486-pc-linux-gnu, compiled by GCC cc (GCC) 4.0.2 20050821 (prerelease) (Debian 4.0.1-6) + + +-- + + - Rich Doughty + +From pgsql-www-owner@postgresql.org Thu Nov 17 04:43:26 2005 +X-Original-To: pgsql-www-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 09119D9007; + Wed, 16 Nov 2005 21:34:25 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 84452-06; Thu, 17 Nov 2005 01:34:28 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from houston.familyhealth.com.au (houston.au.fhnetwork.com + [203.22.197.21]) + by svr1.postgresql.org (Postfix) with ESMTP id 1F329D8D8F; + Wed, 16 Nov 2005 21:34:23 -0400 (AST) +Received: from houston.familyhealth.com.au (localhost [127.0.0.1]) + by houston.familyhealth.com.au (Postfix) with ESMTP id 8803625077; + Thu, 17 Nov 2005 09:34:26 +0800 (WST) +Received: from [127.0.0.1] (work-40.internal [192.168.0.40]) + by houston.familyhealth.com.au (Postfix) with ESMTP id 61F9F2507D; + Thu, 17 Nov 2005 09:34:25 +0800 (WST) +Message-ID: <437BDF22.9030109@familyhealth.com.au> +Date: Thu, 17 Nov 2005 09:38:42 +0800 +From: Christopher Kings-Lynne <chriskl@familyhealth.com.au> +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Simon Riggs <simon@2ndquadrant.com> +Cc: pgsql-www@postgresql.org, Tom Lane <tgl@sss.pgh.pa.us>, + Steve Wampler <swampler@noao.edu>, + Postgres-performance <pgsql-performance@postgresql.org> +Subject: Re: [PERFORM] Help speeding up delete +References: <43790A99.9050603@noao.edu> <4162.1132011763@sss.pgh.pa.us> + <1132171206.4959.60.camel@localhost.localdomain> +In-Reply-To: <1132171206.4959.60.camel@localhost.localdomain> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-familyhealth-MailScanner-Information: Please contact the ISP for more + information +X-familyhealth-MailScanner: Found to be clean +X-familyhealth-MailScanner-From: chriskl@familyhealth.com.au +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.037 required=5 tests=[AWL=0.037] +X-Spam-Score: 0.037 +X-Spam-Level: +X-Archive-Number: 200511/106 +X-Sequence-Number: 8821 + +>>Update to 7.4 or later ;-) +>> +>>Quite seriously, if you're still using 7.2.4 for production purposes +>>you could justifiably be accused of negligence. There are three or four +>>data-loss-grade bugs fixed in the later 7.2.x releases, not to mention +>>security holes; and that was before we abandoned support for 7.2. +>>You *really* need to be thinking about an update. +> +> +> Perhaps we should put a link on the home page underneath LATEST RELEASEs +> saying +> 7.2: de-supported +> +> with a link to a scary note along the lines of the above. + +I strongly support an explicit desupported notice for 7.2 and below on +the website... + +Chris + + +From pgsql-www-owner@postgresql.org Thu Nov 17 04:43:54 2005 +X-Original-To: pgsql-www-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 84D17D7FA3; + Wed, 16 Nov 2005 21:36:25 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 83146-10; Thu, 17 Nov 2005 01:36:27 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from houston.familyhealth.com.au (houston.au.fhnetwork.com + [203.22.197.21]) + by svr1.postgresql.org (Postfix) with ESMTP id 6B6E8D6FCB; + Wed, 16 Nov 2005 21:36:22 -0400 (AST) +Received: from houston.familyhealth.com.au (localhost [127.0.0.1]) + by houston.familyhealth.com.au (Postfix) with ESMTP id C38BC25079; + Thu, 17 Nov 2005 09:36:25 +0800 (WST) +Received: from [127.0.0.1] (work-40.internal [192.168.0.40]) + by houston.familyhealth.com.au (Postfix) with ESMTP id D149225078; + Thu, 17 Nov 2005 09:36:24 +0800 (WST) +Message-ID: <437BDF9A.4060700@familyhealth.com.au> +Date: Thu, 17 Nov 2005 09:40:42 +0800 +From: Christopher Kings-Lynne <chriskl@familyhealth.com.au> +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Simon Riggs <simon@2ndquadrant.com> +Cc: pgsql-www@postgresql.org, Tom Lane <tgl@sss.pgh.pa.us>, + Steve Wampler <swampler@noao.edu>, + Postgres-performance <pgsql-performance@postgresql.org> +Subject: Re: [PERFORM] Help speeding up delete +References: <43790A99.9050603@noao.edu> <4162.1132011763@sss.pgh.pa.us> + <1132171206.4959.60.camel@localhost.localdomain> +In-Reply-To: <1132171206.4959.60.camel@localhost.localdomain> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-familyhealth-MailScanner-Information: Please contact the ISP for more + information +X-familyhealth-MailScanner: Found to be clean +X-familyhealth-MailScanner-From: chriskl@familyhealth.com.au +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.035 required=5 tests=[AWL=0.035] +X-Spam-Score: 0.035 +X-Spam-Level: +X-Archive-Number: 200511/107 +X-Sequence-Number: 8822 + +> Perhaps we should put a link on the home page underneath LATEST RELEASEs +> saying +> 7.2: de-supported +> +> with a link to a scary note along the lines of the above. +> +> ISTM that there are still too many people on older releases. +> +> We probably need an explanation of why we support so many releases (in +> comparison to licenced software) and a note that this does not imply the +> latest releases are not yet production (in comparison to MySQL or Sybase +> who have been in beta for a very long time). + +By the way, is anyone interested in creating some sort of online +repository on pgsql.org or pgfoundry where we can keep statically +compiled pg_dump/all for several platforms for 8.1? + +That way if someone wanted to upgrade from 7.2 to 8.1, they can just +grab the latest dumper from the website, dump their old database, then +upgrade easily. + +In my experience not many pgsql admins have test servers or the skills +to build up test machines with the latest pg_dump, etc. (Seriously.) +In fact, few realise at all that they should use the 8.1 dumper. + +Chris + + +From pgsql-www-owner@postgresql.org Thu Nov 17 05:19:31 2005 +X-Original-To: pgsql-www-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 53E59DB86E; + Thu, 17 Nov 2005 05:19:30 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 07910-05-2; Thu, 17 Nov 2005 09:19:30 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mx-2.sollentuna.net (mx-2.sollentuna.net [195.84.163.199]) + by svr1.postgresql.org (Postfix) with ESMTP id 6E77BDB4CF; + Thu, 17 Nov 2005 05:19:27 -0400 (AST) +Received: from ALGOL.sollentuna.se (janus.sollentuna.se [62.65.68.67]) + by mx-2.sollentuna.net (Postfix) with ESMTP + id 242948F28C; Thu, 17 Nov 2005 10:19:29 +0100 (CET) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Subject: Re: [PERFORM] Help speeding up delete +Date: Thu, 17 Nov 2005 10:19:28 +0100 +Message-ID: <6BCB9D8A16AC4241919521715F4D8BCE6C7BF2@algol.sollentuna.se> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [pgsql-www] [PERFORM] Help speeding up delete +thread-index: AcXrU4k7PjwS8+z1TDi66qZLjnVilgABDMAQ +From: "Magnus Hagander" <mha@sollentuna.net> +To: "Christopher Kings-Lynne" <chriskl@familyhealth.com.au>, + "Simon Riggs" <simon@2ndquadrant.com> +Cc: <pgsql-www@postgresql.org>, "Tom Lane" <tgl@sss.pgh.pa.us>, + "Steve Wampler" <swampler@noao.edu>, + "Postgres-performance" <pgsql-performance@postgresql.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/108 +X-Sequence-Number: 8823 + +> > Perhaps we should put a link on the home page underneath LATEST=20 +> > RELEASEs saying +> > 7.2: de-supported +> >=20 +> > with a link to a scary note along the lines of the above. +> >=20 +> > ISTM that there are still too many people on older releases. +> >=20 +> > We probably need an explanation of why we support so many=20 +> releases (in=20 +> > comparison to licenced software) and a note that this does=20 +> not imply=20 +> > the latest releases are not yet production (in comparison=20 +> to MySQL or=20 +> > Sybase who have been in beta for a very long time). +>=20 +> By the way, is anyone interested in creating some sort of=20 +> online repository on pgsql.org or pgfoundry where we can keep=20 +> statically compiled pg_dump/all for several platforms for 8.1? +>=20 +> That way if someone wanted to upgrade from 7.2 to 8.1, they=20 +> can just grab the latest dumper from the website, dump their=20 +> old database, then upgrade easily. + +But if they're upgrading to 8.1, don't they already have the new +pg_dump? How else are they going to dump their *new* database? + +> In my experience not many pgsql admins have test servers or=20 +> the skills to build up test machines with the latest pg_dump,=20 + +I don't, but I still dump with the latest version - works fine both on +linux and windows for me...=20 + +> etc. (Seriously.) In fact, few realise at all that they=20 +> should use the 8.1 dumper. + +That most people don't know they should use the new one I understand +though. But I don't see how this will help against that :-) + +//Magnus + +From pgsql-performance-owner@postgresql.org Thu Nov 17 07:20:00 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id AB84CD6FF4 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 07:19:57 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 19851-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 11:19:59 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from cassarossa.samfundet.no (cassarossa.samfundet.no + [129.241.93.19]) + by svr1.postgresql.org (Postfix) with ESMTP id AA155D6853 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 07:19:53 -0400 (AST) +Received: from trofast.sesse.net ([129.241.93.32]) + by cassarossa.samfundet.no with esmtp (Exim 4.50) id 1Echo2-0000hf-PJ + for pgsql-performance@postgresql.org; Thu, 17 Nov 2005 12:19:56 +0100 +Received: from sesse by trofast.sesse.net with local (Exim 3.36 #1 (Debian)) + id 1Echnb-0006uH-00 + for <pgsql-performance@postgresql.org>; Thu, 17 Nov 2005 12:19:27 +0100 +Date: Thu, 17 Nov 2005 12:19:27 +0100 +From: "Steinar H. Gunderson" <sgunderson@bigfoot.com> +To: pgsql-performance@postgresql.org +Subject: Re: Help speeding up delete +Message-ID: <20051117111927.GB26459@uio.no> +Mail-Followup-To: pgsql-performance@postgresql.org +References: <43790A99.9050603@noao.edu> <4162.1132011763@sss.pgh.pa.us> + <1132171206.4959.60.camel@localhost.localdomain> + <437BDF9A.4060700@familyhealth.com.au> +MIME-Version: 1.0 +Content-Type: text/plain; charset=utf-8 +Content-Disposition: inline +In-Reply-To: <437BDF9A.4060700@familyhealth.com.au> +X-Operating-System: Linux 2.6.14 on a i686 +X-Message-Flag: Outlook? --> http://www.mozilla.org/products/thunderbird/ +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/313 +X-Sequence-Number: 15570 + +On Thu, Nov 17, 2005 at 09:40:42AM +0800, Christopher Kings-Lynne wrote: +> In my experience not many pgsql admins have test servers or the skills +> to build up test machines with the latest pg_dump, etc. (Seriously.) +> In fact, few realise at all that they should use the 8.1 dumper. + +Isn't your distribution supposed to do this for you? Mine does these days... + +/* Steinar */ +-- +Homepage: http://www.sesse.net/ + +From pgsql-performance-owner@postgresql.org Thu Nov 17 08:28:43 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A321FDB4C2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 08:28:42 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 28712-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 12:28:44 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 39948DB4CF + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 08:28:39 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id DDD9031059; Thu, 17 Nov 2005 13:28:41 +0100 (MET) +From: William Yu <wyu@talisys.com> +X-Newsgroups: pgsql.performance +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Thu, 17 Nov 2005 04:28:38 -0800 +Organization: Hub.Org Networking Services +Lines: 19 +Message-ID: <dlht1h$2q3r$1@news.hub.org> +References: <2F769A036C2082469C3A4BF2603694C601E7686E@ex2k.bankofamerica.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +User-Agent: Mozilla Thunderbird 1.0 (X11/20041206) +X-Accept-Language: en-us, en +In-Reply-To: <2F769A036C2082469C3A4BF2603694C601E7686E@ex2k.bankofamerica.com> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/314 +X-Sequence-Number: 15571 + +Welty, Richard wrote: +> David Boreham wrote: +> +>>I guess I've never bought into the vendor story that there are +>>two reliability grades. Why would they bother making two +>>different kinds of bearing, motor etc ? Seems like it's more +>>likely an excuse to justify higher prices. +> +> +> then how to account for the fact that bleeding edge SCSI drives +> turn at twice the rpms of bleeding edge consumer drives? + +The motors spin twice as fast? + +I'm pretty sure the original comment was based on drives w/ similar +specs. E.g. 7200RPM "enterprise" drives versus 7200RPM "consumer" drives. + +Next time one of my 7200RPM SCSIs fail, I'll take it apart and compare +the insides to an older 7200RPM IDE from roughly the same era. + +From pgsql-performance-owner@postgresql.org Thu Nov 17 10:34:56 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 52AB7D7003 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 10:34:53 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 45817-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 14:34:56 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from yertle.kcilink.com (yertle.kcilink.com [65.205.34.180]) + by svr1.postgresql.org (Postfix) with ESMTP id D43B7DB90D + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 10:34:49 -0400 (AST) +Received: from [192.168.7.103] (host-103.int.kcilink.com [192.168.7.103]) + by yertle.kcilink.com (Postfix) with ESMTP id 30F09B80A + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 09:34:53 -0500 (EST) +Mime-Version: 1.0 (Apple Message framework v746.2) +In-Reply-To: <b41c75520511161350u3ed6f4b1x@mail.gmail.com> +References: <1B80C974ABFB23429A403B6667FE84C71066E8@seiumain.SEIU.local> + <b41c75520511150028o553e6bb5j@mail.gmail.com> + <D1ABFA1F-FEB0-4E01-BC2E-482535A5DB28@khera.org> + <b41c75520511161350u3ed6f4b1x@mail.gmail.com> +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: <E9467EC3-31C3-487F-816A-9C2E42394CA3@khera.org> +Content-Transfer-Encoding: 7bit +From: Vivek Khera <vivek@khera.org> +Subject: Re: Hardware/OS recommendations for large databases (5TB) +Date: Thu, 17 Nov 2005 09:34:52 -0500 +To: Postgresql Performance <pgsql-performance@postgresql.org> +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/315 +X-Sequence-Number: 15572 + + +On Nov 16, 2005, at 4:50 PM, Claus Guttesen wrote: + +> I'm (also) FreeBSD-biased but I'm not shure whether the 5 TB fs will +> work so well if tools like fsck are needed. Gvinum could be one option +> but I don't have any experience in that area. + +Then look into an external filer and mount via NFS. Then it is not +FreeBSD's responsibility to manage the volume. + + +From pgsql-www-owner@postgresql.org Thu Nov 17 11:08:25 2005 +X-Original-To: pgsql-www-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 49C24DB951; + Thu, 17 Nov 2005 11:05:15 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 48368-08; Thu, 17 Nov 2005 15:05:18 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 3645FDB975; + Thu, 17 Nov 2005 11:05:11 -0400 (AST) +Received: from vscan03.westnet.com.au (vscan03.westnet.com.au [203.10.1.142]) + by svr2.postgresql.org (Postfix) with ESMTP id 8F2B3F0BEC; + Thu, 17 Nov 2005 15:05:15 +0000 (GMT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by localhost (Postfix) with ESMTP id 315CCB60294; + Thu, 17 Nov 2005 23:05:11 +0800 (WST) +Received: from vscan03.westnet.com.au ([127.0.0.1]) + by localhost (vscan03.westnet.com.au [127.0.0.1]) (amavisd-new, + port 10024) + with ESMTP id 03875-07-2; Thu, 17 Nov 2005 23:05:11 +0800 (WST) +Received: from [202.72.133.22] (dsl-202-72-133-22.wa.westnet.com.au + [202.72.133.22]) + by vscan03.westnet.com.au (Postfix) with ESMTP id 81F04B60280; + Thu, 17 Nov 2005 23:05:10 +0800 (WST) +Message-ID: <437C9C26.309@familyhealth.com.au> +Date: Thu, 17 Nov 2005 23:05:10 +0800 +From: Christopher Kings-Lynne <chriskl@familyhealth.com.au> +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Magnus Hagander <mha@sollentuna.net> +Cc: Simon Riggs <simon@2ndquadrant.com>, pgsql-www@postgresql.org, + Tom Lane <tgl@sss.pgh.pa.us>, Steve Wampler <swampler@noao.edu>, + Postgres-performance <pgsql-performance@postgresql.org> +Subject: Re: [PERFORM] Help speeding up delete +References: <6BCB9D8A16AC4241919521715F4D8BCE6C7BF2@algol.sollentuna.se> +In-Reply-To: <6BCB9D8A16AC4241919521715F4D8BCE6C7BF2@algol.sollentuna.se> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/112 +X-Sequence-Number: 8827 + +>>That way if someone wanted to upgrade from 7.2 to 8.1, they +>>can just grab the latest dumper from the website, dump their +>>old database, then upgrade easily. +> +> But if they're upgrading to 8.1, don't they already have the new +> pg_dump? How else are they going to dump their *new* database? + +Erm. Usually when you install the new package/port for 8.1, you cannot +have both new and old installed at the same time man. Remember they +both store exactly the same binary files in exactly the same place. + +>>In my experience not many pgsql admins have test servers or +>>the skills to build up test machines with the latest pg_dump, +> +> I don't, but I still dump with the latest version - works fine both on +> linux and windows for me... + +So you're saying you DO have the skills to do it then... + +>>etc. (Seriously.) In fact, few realise at all that they +>>should use the 8.1 dumper. +> +> That most people don't know they should use the new one I understand +> though. But I don't see how this will help against that :-) + +It'll make it easy... + +Chris + +From pgsql-performance-owner@postgresql.org Thu Nov 17 11:07:45 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0F4B4D963C + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 11:07:44 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 47569-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 15:07:47 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 879ADD6853 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 11:07:41 -0400 (AST) +Received: from vscan03.westnet.com.au (vscan03.westnet.com.au [203.10.1.142]) + by svr2.postgresql.org (Postfix) with ESMTP id 15DD8F0BF8 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 15:07:45 +0000 (GMT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by localhost (Postfix) with ESMTP id 28560B60184; + Thu, 17 Nov 2005 23:07:43 +0800 (WST) +Received: from vscan03.westnet.com.au ([127.0.0.1]) + by localhost (vscan03.westnet.com.au [127.0.0.1]) (amavisd-new, + port 10024) + with ESMTP id 04578-05-2; Thu, 17 Nov 2005 23:07:43 +0800 (WST) +Received: from [202.72.133.22] (dsl-202-72-133-22.wa.westnet.com.au + [202.72.133.22]) + by vscan03.westnet.com.au (Postfix) with ESMTP id D140EB603EE; + Thu, 17 Nov 2005 23:07:41 +0800 (WST) +Message-ID: <437C9CBE.8020907@familyhealth.com.au> +Date: Thu, 17 Nov 2005 23:07:42 +0800 +From: Christopher Kings-Lynne <chriskl@familyhealth.com.au> +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: "Steinar H. Gunderson" <sgunderson@bigfoot.com> +Cc: pgsql-performance@postgresql.org +Subject: Re: Help speeding up delete +References: <43790A99.9050603@noao.edu> <4162.1132011763@sss.pgh.pa.us> + <1132171206.4959.60.camel@localhost.localdomain> + <437BDF9A.4060700@familyhealth.com.au> + <20051117111927.GB26459@uio.no> +In-Reply-To: <20051117111927.GB26459@uio.no> +Content-Type: text/plain; charset=UTF-8; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/317 +X-Sequence-Number: 15574 + +> Isn't your distribution supposed to do this for you? Mine does these days... + +A distribution that tries to automatically do a major postgresql update +is doomed to fail - spectacularly... + +Chris + +From pgsql-www-owner@postgresql.org Thu Nov 17 11:17:13 2005 +X-Original-To: pgsql-www-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9D03EDB972; + Thu, 17 Nov 2005 11:13:35 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 47671-09; Thu, 17 Nov 2005 15:13:39 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from noao.edu (noao.edu [140.252.1.54]) + by svr1.postgresql.org (Postfix) with ESMTP id B5087DB97F; + Thu, 17 Nov 2005 11:13:32 -0400 (AST) +X-TFF-CGPSA-Version: 1.4f1 +X-TFF-CGPSA-Filter: Scanned +Received: from weaver.tuc.noao.edu ([140.252.14.8] verified) + by noao.edu (CommuniGate Pro SMTP 5.0.1) + with ESMTPS id 21690410; Thu, 17 Nov 2005 08:13:31 -0700 +Received: from [127.0.0.1] (localhost.localdomain [127.0.0.1]) + by weaver.tuc.noao.edu (8.13.1/8.13.1) with ESMTP id jAHFDU0r002829; + Thu, 17 Nov 2005 08:13:30 -0700 +Message-ID: <437C9E1A.50505@noao.edu> +Date: Thu, 17 Nov 2005 08:13:30 -0700 +From: Steve Wampler <swampler@noao.edu> +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Christopher Kings-Lynne <chriskl@familyhealth.com.au> +CC: Magnus Hagander <mha@sollentuna.net>, Simon Riggs <simon@2ndquadrant.com>, + pgsql-www@postgresql.org, Tom Lane <tgl@sss.pgh.pa.us>, + Postgres-performance <pgsql-performance@postgresql.org> +Subject: Re: [PERFORM] Help speeding up delete +References: <6BCB9D8A16AC4241919521715F4D8BCE6C7BF2@algol.sollentuna.se> + <437C9C26.309@familyhealth.com.au> +In-Reply-To: <437C9C26.309@familyhealth.com.au> +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/113 +X-Sequence-Number: 8828 + +Christopher Kings-Lynne wrote: +>> That most people don't know they should use the new one I understand +>> though. But I don't see how this will help against that :-) +> +> It'll make it easy... + +As the miscreant that caused this thread to get started, let me +*wholeheartedly* agree with Chris. An easy way to get the pg_dump +for the upgrade target to run with the upgradable source +would work wonders. (Instructions included, of course.) + + +-- +Steve Wampler -- swampler@noao.edu +The gods that smiled on your birth are now laughing out loud. + +From pgsql-www-owner@postgresql.org Thu Nov 17 11:39:08 2005 +X-Original-To: pgsql-www-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 2AF7FD7B8B; + Thu, 17 Nov 2005 11:39:07 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 52805-03; Thu, 17 Nov 2005 15:39:09 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mx-2.sollentuna.net (mx-2.sollentuna.net [195.84.163.199]) + by svr1.postgresql.org (Postfix) with ESMTP id CD1C8DB94C; + Thu, 17 Nov 2005 11:39:02 -0400 (AST) +Received: from ALGOL.sollentuna.se (janus.sollentuna.se [62.65.68.67]) + by mx-2.sollentuna.net (Postfix) with ESMTP + id 636288F28C; Thu, 17 Nov 2005 16:39:06 +0100 (CET) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Subject: Re: [PERFORM] Help speeding up delete +Date: Thu, 17 Nov 2005 16:39:06 +0100 +Message-ID: <6BCB9D8A16AC4241919521715F4D8BCE6C7C03@algol.sollentuna.se> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [pgsql-www] [PERFORM] Help speeding up delete +thread-index: AcXriFF+MaR09uvOR3ivzN3N2SRPNQABHMjA +From: "Magnus Hagander" <mha@sollentuna.net> +To: "Christopher Kings-Lynne" <chriskl@familyhealth.com.au> +Cc: "Simon Riggs" <simon@2ndquadrant.com>, + <pgsql-www@postgresql.org>, "Tom Lane" <tgl@sss.pgh.pa.us>, + "Steve Wampler" <swampler@noao.edu>, + "Postgres-performance" <pgsql-performance@postgresql.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/114 +X-Sequence-Number: 8829 + +> >>That way if someone wanted to upgrade from 7.2 to 8.1, they=20 +> can just=20 +> >>grab the latest dumper from the website, dump their old=20 +> database, then=20 +> >>upgrade easily. +> >=20 +> > But if they're upgrading to 8.1, don't they already have the new=20 +> > pg_dump? How else are they going to dump their *new* database? +>=20 +> Erm. Usually when you install the new package/port for 8.1,=20 +> you cannot have both new and old installed at the same time=20 +> man. Remember they both store exactly the same binary files=20 +> in exactly the same place. + +Urrk. Didn't think of that. I always install from source on Unix, which +doesn't have the problem. And the Windows port doesn't have this problem +- it will put the binaries in a version dependant directory. + +One could claim the packages are broken ;-), but that's not gonig to +help here, I know... + +(I always install in pgsql-<version>, and then symlink pgsql there..) + + +> >>etc. (Seriously.) In fact, few realise at all that they should use=20 +> >>the 8.1 dumper. +> >=20 +> > That most people don't know they should use the new one I=20 +> understand=20 +> > though. But I don't see how this will help against that :-) +>=20 +> It'll make it easy... + +You assume they know enough to download it. If they don't know to look +for it, they still won't find it. + +But the bottom line: I can see how it would be helpful if you're on a +distro which packages postgresql in a way that prevents you from +installing more than one version at the same time. + +//Magnus + +From pgsql-www-owner@postgresql.org Thu Nov 17 12:02:46 2005 +X-Original-To: pgsql-www-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id F02C8D967F; + Thu, 17 Nov 2005 11:56:31 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 55332-03; Thu, 17 Nov 2005 15:56:35 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from koolancexeon.g2switchworks.com (mail.g2switchworks.com + [63.87.162.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 0E06AD78B6; + Thu, 17 Nov 2005 11:56:28 -0400 (AST) +Received: mail.g2switchworks.com 10.10.1.8 from 10.10.1.37 10.10.1.37 via HTTP + with MS-WebStorage 6.5.6944 +Received: from state.g2switchworks.com by mail.g2switchworks.com; + 17 Nov 2005 09:56:32 -0600 +Subject: Re: [PERFORM] Help speeding up delete +From: Scott Marlowe <smarlowe@g2switchworks.com> +To: Christopher Kings-Lynne <chriskl@familyhealth.com.au> +Cc: Simon Riggs <simon@2ndquadrant.com>, pgsql-www@postgresql.org, + Tom Lane <tgl@sss.pgh.pa.us>, Steve Wampler <swampler@noao.edu>, + Postgres-performance <pgsql-performance@postgresql.org> +In-Reply-To: <437BDF9A.4060700@familyhealth.com.au> +References: <43790A99.9050603@noao.edu> <4162.1132011763@sss.pgh.pa.us> + <1132171206.4959.60.camel@localhost.localdomain> + <437BDF9A.4060700@familyhealth.com.au> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Message-Id: <1132242992.3582.98.camel@state.g2switchworks.com> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) +Date: Thu, 17 Nov 2005 09:56:32 -0600 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/116 +X-Sequence-Number: 8831 + +On Wed, 2005-11-16 at 19:40, Christopher Kings-Lynne wrote: +> > Perhaps we should put a link on the home page underneath LATEST RELEASEs +> > saying +> > 7.2: de-supported +> > +> > with a link to a scary note along the lines of the above. +> > +> > ISTM that there are still too many people on older releases. +> > +> > We probably need an explanation of why we support so many releases (in +> > comparison to licenced software) and a note that this does not imply the +> > latest releases are not yet production (in comparison to MySQL or Sybase +> > who have been in beta for a very long time). +> +> By the way, is anyone interested in creating some sort of online +> repository on pgsql.org or pgfoundry where we can keep statically +> compiled pg_dump/all for several platforms for 8.1? +> +> That way if someone wanted to upgrade from 7.2 to 8.1, they can just +> grab the latest dumper from the website, dump their old database, then +> upgrade easily. +> +> In my experience not many pgsql admins have test servers or the skills +> to build up test machines with the latest pg_dump, etc. (Seriously.) +> In fact, few realise at all that they should use the 8.1 dumper. + +I would especially like such a thing available as an RPM. A +pgsql-8.1-clienttools.rpm or something like that, with psql, pg_dump, +pg_restore, and what other command line tools you can think of that +would help. + +From pgsql-www-owner@postgresql.org Thu Nov 17 13:02:32 2005 +X-Original-To: pgsql-www-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 046FBDB15E + for <pgsql-www-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 12:57:41 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 68794-06 + for <pgsql-www-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 16:57:40 +0000 (GMT) +X-Greylist: delayed 00:28:35.330519 by SQLgrey- +Received: from cicero0.cybercity.dk (cicero0.cybercity.dk [212.242.40.52]) + by svr1.postgresql.org (Postfix) with ESMTP id 31C09D7B8B + for <pgsql-www@postgresql.org>; Thu, 17 Nov 2005 12:57:37 -0400 (AST) +Received: from [192.168.0.79] (0x3e42eeca.adsl.cybercity.dk [62.66.238.202]) + by cicero0.cybercity.dk (Postfix) with ESMTP + id 31BE22A153; Thu, 17 Nov 2005 17:28:16 +0100 (CET) +Message-ID: <437CAF4B.2030100@krap.dk> +Date: Thu, 17 Nov 2005 17:26:51 +0100 +From: Svenne Krap <svenne@krap.dk> +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Magnus Hagander <mha@sollentuna.net>, pgsql-www@postgresql.org +Subject: Re: [PERFORM] Help speeding up delete +References: <6BCB9D8A16AC4241919521715F4D8BCE6C7C03@algol.sollentuna.se> +In-Reply-To: <6BCB9D8A16AC4241919521715F4D8BCE6C7C03@algol.sollentuna.se> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/122 +X-Sequence-Number: 8837 + + +>You assume they know enough to download it. If they don't know to look +>for it, they still won't find it. +> +> +I think there should be a big, fat warning in the release notes. +Something like: + +WARNING: Upgrading to version X.Y requires a full dump/restore cycle. +Please download the appropriate dump-utility from http://postgresql.org/dumputils/X.Y/ +and make a copy of your database before installing the new version X.Y. + + +And then link to a dir with the statically linked pg_dump (and -all) for +the most common platforms. I must admit, I did not know that one should +use the new tool in a cyclus (and I have used Pg almost exclusively +since 7.0). That could also be the place to add a line about version S.T +is now considered obsolete and unsupported. + +/Svenne + +From pgsql-performance-owner@postgresql.org Thu Nov 17 13:25:47 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5FA78DA792 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 13:25:46 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 74365-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 17:25:42 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from cassarossa.samfundet.no (cassarossa.samfundet.no + [129.241.93.19]) + by svr1.postgresql.org (Postfix) with ESMTP id 5E558D71B1 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 13:25:40 -0400 (AST) +Received: from trofast.ipv6.sesse.net ([2001:700:300:dc03:20e:cff:fe36:a766] + helo=trofast.sesse.net) + by cassarossa.samfundet.no with esmtp (Exim 4.50) id 1EcnVz-0006jv-Qk + for pgsql-performance@postgresql.org; Thu, 17 Nov 2005 18:25:40 +0100 +Received: from sesse by trofast.sesse.net with local (Exim 3.36 #1 (Debian)) + id 1EcnVX-0007Km-00 + for <pgsql-performance@postgresql.org>; Thu, 17 Nov 2005 18:25:11 +0100 +Date: Thu, 17 Nov 2005 18:25:11 +0100 +From: "Steinar H. Gunderson" <sgunderson@bigfoot.com> +To: pgsql-performance@postgresql.org +Subject: Re: Help speeding up delete +Message-ID: <20051117172511.GA28121@uio.no> +Mail-Followup-To: pgsql-performance@postgresql.org +References: <43790A99.9050603@noao.edu> <4162.1132011763@sss.pgh.pa.us> + <1132171206.4959.60.camel@localhost.localdomain> + <437BDF9A.4060700@familyhealth.com.au> + <20051117111927.GB26459@uio.no> + <437C9CBE.8020907@familyhealth.com.au> +MIME-Version: 1.0 +Content-Type: text/plain; charset=utf-8 +Content-Disposition: inline +In-Reply-To: <437C9CBE.8020907@familyhealth.com.au> +X-Operating-System: Linux 2.6.14 on a i686 +X-Message-Flag: Outlook? --> http://www.mozilla.org/products/thunderbird/ +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/321 +X-Sequence-Number: 15578 + +On Thu, Nov 17, 2005 at 11:07:42PM +0800, Christopher Kings-Lynne wrote: +>> Isn't your distribution supposed to do this for you? Mine does these +>> days... +> A distribution that tries to automatically do a major postgresql update +> is doomed to fail - spectacularly... + +Automatically? Well, you can install the two versions side-by-side, and do +pg_upgradecluster, which ports your configuration to the new version and does +a pg_dump between the two versions; exactly what a system administrator would +do. Of course, stuff _can_ fail, but it works for the simple cases, and a +great deal of the not-so-simple cases. I did this for our cluster the other +day (130 wildly different databases, from 7.4 to 8.1) and it worked +flawlessly. + +I do not really see why all the distributions could do something like this, +instead of mucking around with special statically compiled pg_dumps and the +like... + +/* Steinar */ +-- +Homepage: http://www.sesse.net/ + +From pgsql-performance-owner@postgresql.org Thu Nov 17 16:48:32 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id F002EDB98A + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 16:48:30 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 19624-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 20:48:31 +0000 (GMT) +X-Greylist: delayed 03:01:11.321971 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 20C5EDB1D4 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 16:48:26 -0400 (AST) +Received: from soufre.accelance.net (soufre.accelance.net [213.162.48.15]) + by svr2.postgresql.org (Postfix) with ESMTP id 25718F0B7C + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 17:47:14 +0000 (GMT) +Received: from [213.162.49.207] (gs.team.openwide.fr [213.162.49.207]) + (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) + (No client certificate requested) + by soufre.accelance.net (Postfix) with ESMTP id DC8B15DD9 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 18:47:09 +0100 (CET) +Message-ID: <437CC21D.8070402@openwide.fr> +Date: Thu, 17 Nov 2005 18:47:09 +0100 +From: Guillaume Smet <guillaume.smet@openwide.fr> +User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc3 (X11/20050929) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: weird performances problem +Content-Type: multipart/mixed; boundary="------------080708010505040208070501" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/331 +X-Sequence-Number: 15588 + +This is a multi-part message in MIME format. +--------------080708010505040208070501 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit + +Hi all, + +We are operating a 1.5GB postgresql database for a year and we have +problems for nearly a month. Usually everything is OK with the database, +queries are executed fast even if they are complicated but sometimes and +for half an hour, we have a general slow down. + +The server is a dedicated quad xeon with 4GB and a RAID1 array for the +system and a RAID10 one for postgresql data. We have very few +updates/inserts/deletes during the day. + +Postgresql version is 7.4.8. + +- the database is vacuumed, analyzed regularly (but we are not using +autovacuum) and usually performs pretty well ; +- IOs are OK, the database is entirely in RAM (see top.txt and +iostat.txt attached) ; +- CPUs are usually 25% idle, load is never really growing and its +maximum is below 5 ; +- I attached two plans for a simple query, the one is what we have when +the server is fast, the other when we have a slow down: it's exactly the +same plan but, as you can see it, the time to fetch the first row from +indexes is quite high for the slow query ; +- during this slow down, queries that usually take 500ms can take up to +60 seconds (and sometimes even more) ; +- we have up to 130 permanent connections from our apache servers during +this slow down as we have a lot of apache children waiting for a response. + +I attached a vmstat output. Context switches are quite high but I'm not +sure it can be called a context switch storm and that this is the cause +of our problem. + +Thanks for any advice or idea to help us understanding this problem and +hopefully solve it. + +Regards, + +-- +Guillaume + +--------------080708010505040208070501 +Content-Type: text/plain; + name="iostat.txt" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline; + filename="iostat.txt" + +[root@bd root]# iostat 10 + +Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn +sda 7.20 0.00 92.00 0 920 +sda1 0.00 0.00 0.00 0 0 +sda2 6.40 0.00 78.40 0 784 +sda3 0.00 0.00 0.00 0 0 +sda4 0.00 0.00 0.00 0 0 +sda5 0.00 0.00 0.00 0 0 +sda6 0.80 0.00 13.60 0 136 +sdb 5.00 0.00 165.60 0 1656 +sdb1 5.00 0.00 165.60 0 1656 + +Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn +sda 1.30 0.00 20.80 0 208 +sda1 0.00 0.00 0.00 0 0 +sda2 0.70 0.00 9.60 0 96 +sda3 0.00 0.00 0.00 0 0 +sda4 0.00 0.00 0.00 0 0 +sda5 0.00 0.00 0.00 0 0 +sda6 0.60 0.00 11.20 0 112 +sdb 5.40 0.00 173.60 0 1736 +sdb1 5.40 0.00 173.60 0 1736 + +Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn +sda 2.20 0.00 28.00 0 280 +sda1 0.00 0.00 0.00 0 0 +sda2 2.20 0.00 28.00 0 280 +sda3 0.00 0.00 0.00 0 0 +sda4 0.00 0.00 0.00 0 0 +sda5 0.00 0.00 0.00 0 0 +sda6 0.00 0.00 0.00 0 0 +sdb 5.20 0.00 171.20 0 1712 +sdb1 5.20 0.00 171.20 0 1712 + + +--------------080708010505040208070501 +Content-Type: text/plain; + name="plan1.txt" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline; + filename="plan1.txt" + + QUERY PLAN +---------------------------------------------------------------------------------------------------------------------------------- + Nested Loop (cost=0.00..13.52 rows=2 width=1119) (actual time=0.154..0.167 rows=1 loops=1) + -> Index Scan using pk_newslang on newslang nl (cost=0.00..3.87 rows=1 width=1004) (actual time=0.053..0.055 rows=1 loops=1) + Index Cond: (((codelang)::text = 'FRA'::text) AND (3498704 = numnews)) + -> Nested Loop Left Join (cost=0.00..9.61 rows=2 width=119) (actual time=0.050..0.059 rows=1 loops=1) + -> Index Scan using pk_news on news n (cost=0.00..3.31 rows=2 width=98) (actual time=0.021..0.023 rows=1 loops=1) + Index Cond: (numnews = 3498704) + -> Index Scan using pk_photo on photo p (cost=0.00..3.14 rows=1 width=25) (actual time=0.021..0.025 rows=1 loops=1) + Index Cond: (p.numphoto = "outer".numphoto) + Total runtime: 0.320 ms +(9 rows) + + +--------------080708010505040208070501 +Content-Type: text/plain; + name="plan2.txt" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline; + filename="plan2.txt" + + QUERY PLAN +------------------------------------------------------------------------------------------------------------------------------------ + Nested Loop (cost=0.00..13.52 rows=2 width=1119) (actual time=155.286..155.305 rows=1 loops=1) + -> Index Scan using pk_newslang on newslang nl (cost=0.00..3.87 rows=1 width=1004) (actual time=44.575..44.579 rows=1 loops=1) + Index Cond: (((codelang)::text = 'FRA'::text) AND (3498704 = numnews)) + -> Nested Loop Left Join (cost=0.00..9.61 rows=2 width=119) (actual time=110.648..110.660 rows=1 loops=1) + -> Index Scan using pk_news on news n (cost=0.00..3.31 rows=2 width=98) (actual time=0.169..0.174 rows=1 loops=1) + Index Cond: (numnews = 3498704) + -> Index Scan using pk_photo on photo p (cost=0.00..3.14 rows=1 width=25) (actual time=110.451..110.454 rows=1 loops=1) + Index Cond: (p.numphoto = "outer".numphoto) + Total runtime: 155.514 ms +(9 rows) + + + +--------------080708010505040208070501 +Content-Type: text/plain; + name="top.txt" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline; + filename="top.txt" + + 17:08:41 up 19 days, 15:16, 1 user, load average: 4.03, 4.26, 4.36 +288 processes: 285 sleeping, 3 running, 0 zombie, 0 stopped +CPU states: cpu user nice system irq softirq iowait idle + total 59.0% 0.0% 8.8% 0.2% 0.0% 0.0% 31.9% + cpu00 52.3% 0.0% 13.3% 0.9% 0.0% 0.0% 33.3% + cpu01 65.7% 0.0% 7.6% 0.0% 0.0% 0.0% 26.6% + cpu02 58.0% 0.0% 7.6% 0.0% 0.0% 0.0% 34.2% + cpu03 60.0% 0.0% 6.6% 0.0% 0.0% 0.0% 33.3% +Mem: 3857224k av, 3495880k used, 361344k free, 0k shrd, 92160k buff + 2374048k actv, 463576k in_d, 37708k in_c +Swap: 4281272k av, 25412k used, 4255860k free 2173392k cached + + +--------------080708010505040208070501 +Content-Type: text/plain; + name="vmstat.txt" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline; + filename="vmstat.txt" + +[root@bd root]# vmstat 10 +procs memory swap io system cpu + r b swpd free buff cache si so bi bo in cs us sy id wa + 4 0 25412 250160 91736 2170944 0 1 3 3 4 3 5 3 3 0 + 7 0 25412 247160 91736 2171024 0 0 0 116 588 4483 65 4 31 0 + 3 0 25412 235456 91752 2171132 0 0 0 129 491 3670 70 4 26 0 + 5 0 25412 233696 91760 2171216 0 0 0 152 530 4768 61 4 34 0 + 5 0 25412 233248 91768 2171232 0 0 0 183 624 5379 59 5 36 0 + 9 0 25412 195332 91788 2171304 0 0 0 127 541 4811 58 5 37 0 + + +--------------080708010505040208070501-- + +From pgsql-performance-owner@postgresql.org Thu Nov 17 14:07:00 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B3CB8DB616 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 14:06:59 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 82445-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 18:06:58 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 133D7DB38D + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 14:06:56 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAHI6t3T029532; + Thu, 17 Nov 2005 13:06:55 -0500 (EST) +To: Rich Doughty <rich@opusvl.com> +cc: Pgsql-Performance <pgsql-performance@postgresql.org> +Subject: Re: Strange query plan invloving a view +In-reply-to: <437BD7A2.608@opusvl.com> +References: <437BD7A2.608@opusvl.com> +Comments: In-reply-to Rich Doughty <rich@opusvl.com> + message dated "Thu, 17 Nov 2005 01:06:42 +0000" +Date: Thu, 17 Nov 2005 13:06:55 -0500 +Message-ID: <29531.1132250815@sss.pgh.pa.us> +From: Tom Lane <tgl@sss.pgh.pa.us> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.006 required=5 tests=[AWL=0.006] +X-Spam-Score: 0.006 +X-Spam-Level: +X-Archive-Number: 200511/322 +X-Sequence-Number: 15579 + +Rich Doughty <rich@opusvl.com> writes: +> However, the following query (which i believe should be equivalent) + +> SELECT * +> FROM +> tokens.ta_tokenhist h INNER JOIN +> tokens.ta_tokens t ON h.token_id = t.token_id LEFT JOIN +> tokens.ta_tokenhist i ON t.token_id = i.token_id AND +> i.status = 'issued' LEFT JOIN +> tokens.ta_tokenhist s ON t.token_id = s.token_id AND +> s.status = 'sold' LEFT JOIN +> tokens.ta_tokenhist r ON t.token_id = r.token_id AND +> r.status = 'redeemed' +> WHERE +> h.sarreport_id = 9 +> ; + +No, that's not equivalent at all, because the implicit parenthesization +is left-to-right; therefore you've injected the constraint to a few rows +of ta_tokenhist (and therefore only a few rows of ta_tokens) into the +bottom of the LEFT JOIN stack. In the other case the constraint is at +the wrong end of the join stack, and so the full view output gets formed +before anything gets thrown away. + +Some day the Postgres planner will probably be smart enough to rearrange +the join order despite the presence of outer joins ... but today is not +that day. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Thu Nov 17 15:48:42 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 4DBA8DB937 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 15:48:40 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 07825-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 19:48:40 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.195]) + by svr1.postgresql.org (Postfix) with ESMTP id 8DB91DB982 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 15:48:37 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id i28so472561wra + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 11:48:38 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=PJVuSqGD/bQrwPkNupBjPS59ddzQR04MNHI7FUqol7ZExQuM1MVfwXZ9rgL8Ia+q+8OoDMQOYp24xMtcVZnmcnX61/0K2+67BPJdGePYNx49LG2Ko8XtRHTWRpEPrm42z7kyzOxS88/3Z7XKiGHZZXyxVLdZmqzqbDuJEg/FURs= +Received: by 10.54.67.12 with SMTP id p12mr6760115wra; + Thu, 17 Nov 2005 11:48:38 -0800 (PST) +Received: by 10.54.82.5 with HTTP; Thu, 17 Nov 2005 11:48:37 -0800 (PST) +Message-ID: <33c6269f0511171148q7ea67482xd595ea5717956aa2@mail.gmail.com> +Date: Thu, 17 Nov 2005 14:48:38 -0500 +From: Alex Turner <armtuk@gmail.com> +To: William Yu <wyu@talisys.com> +Subject: Re: Hardware/OS recommendations for large databases ( +Cc: pgsql-performance@postgresql.org +In-Reply-To: <dlfjgf$41b$1@news.hub.org> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <dlfjgf$41b$1@news.hub.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/323 +X-Sequence-Number: 15580 + +On 11/16/05, William Yu <wyu@talisys.com> wrote: +> Alex Turner wrote: +> > Spend a fortune on dual core CPUs and then buy crappy disks... I bet +> > for most applications this system will be IO bound, and you will see a +> > nice lot of drive failures in the first year of operation with +> > consumer grade drives. +> > +> > Spend your money on better Disks, and don't bother with Dual Core IMHO +> > unless you can prove the need for it. +> +> I would say the opposite -- you always want Dual Core nowadays. DC +> Opterons simply give you better bang for the buck than single core +> Opterons. Price out a 1xDC system against a 2x1P system -- the 1xDC will +> be cheaper. Do the same for 2xDC versus 4x1P, 4xDC versus 8x1P, 8xDC +> versus 16x1P, etc. -- DC gets cheaper by wider and wider margins because +> those mega-CPU motherboards are astronomically expensive. +> + +Opteron 242 - $178.00 +Opteron 242 - $178.00 +Tyan S2882 - $377.50 +Total: $733.50 + +Opteron 265 - $719.00 +Tyan K8E - $169.00 +Total: $888.00 + +Tyan K8E - doesn't have any PCI-X, so it's also not apples to apples.=20 +Infact I couldn't find a single CPU slot board that did, so you pretty +much have to buy a dual CPU board to get PCI-X. + +1xDC is _not_ cheaper. + +Our DB application does about 5 queries/second peak, plus a heavy +insert job once per day. We only _need_ two CPUs, which is true for a +great many DB applications. Unless you like EJB of course, which will +thrash the crap out of your system. + +Consider the two most used regions for DBs: + +a) OLTP - probably IO bound, large number of queries/sec updating info +on _disks_, not requiring much CPU activity except to retrieve item +infomration which is well indexed and normalized. + +b) Data wharehouse - needs CPU, but probably still IO bound, large +data set that won't fit in RAM will required large amounts of disk +reads. CPU can easily keep up with disk reads. + +I have yet to come across a DB system that wasn't IO bound. + +> DC also gives you a better upgrade path. Let's say you do testing and +> figure 2x246 is the right setup to handle the load. Well instead of +> getting 2x1P, use the same 2P motherboard but only populate 1 CPU w/ a +> DC/270. Now you have a server that can be upgraded to +80% more CPU by +> popping in another DC/270 versus throwing out the entire thing to get a +> 4x1P setup. + +No argument there. But it's pointless if you are IO bound. + +> +> The only questions would be: +> (1) Do you need a SMP server at all? I'd claim yes -- you always need 2+ +> cores whether it's DC or 2P to avoid IO interrupts blocking other +> processes from running. + +At least 2CPUs is always good for precisely those reasons. More than +2CPUs gives diminishing returns. + +> +> (2) Does a DC system perform better than it's Nx1P cousin? My experience +> is yes. Did some rough tests in a drop-in-replacement 1x265 versus 2x244 +> and saw about +10% for DC. All the official benchmarks (Spec, Java, SAP, +> etc) from AMD/Sun/HP/IBM show DCs outperforming the Nx1P setups. + +Maybe true, but the 265 does have a 25% faster FSB than the 244, which +might perhaps play a role. + +> +> (3) Do you need an insane amount of memory? Well here's the case where +> the more expensive motherboard will serve you better since each CPU slot +> has its own bank of memory. Spend more money on memory, get cheaper +> single-core CPUs. + +Remember - large DB is going to be IO bound. Memory will get thrashed +for file block buffers, even if you have large amounts, it's all gonna +be cycled in and out again. + +> +> Of course, this doesn't apply if you are an Intel/Dell-only shop. Xeon +> DCs, while cheaper than their corresponding single-core SMPs, don't have +> the same performance profile of Opteron DCs. Basically, you're paying a +> bit extra so your server can generate a ton more heat. + +Dell/Xeon/Postgres is just a bad combination any day of the week ;) + +Alex. + +From pgsql-performance-owner@postgresql.org Thu Nov 17 15:50:13 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id F0FB5D7B8B + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 15:50:11 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 07729-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 19:50:11 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.194]) + by svr1.postgresql.org (Postfix) with ESMTP id 1501AD6D07 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 15:50:08 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id i28so472893wra + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 11:50:10 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=DqSX66YjpQPeRjGgx8R1BkY5d60+3JpgjARk+cOZRH/StRvAQaAck5tXvaRZT7Np7zZpwmhi0AiyUJijQS97DElwYOYoKusmysuHz9HheaRiGvxO+J1KZdRPaCwr4bxjFolDrdFWZ5aqDoOoX5691VAwVmCZAsJflwBDMxWf4Ms= +Received: by 10.54.76.9 with SMTP id y9mr6761964wra; + Thu, 17 Nov 2005 11:50:10 -0800 (PST) +Received: by 10.54.82.5 with HTTP; Thu, 17 Nov 2005 11:50:10 -0800 (PST) +Message-ID: <33c6269f0511171150j24f2dd2bq607b69994338aa9@mail.gmail.com> +Date: Thu, 17 Nov 2005 14:50:10 -0500 +From: Alex Turner <armtuk@gmail.com> +To: David Boreham <david_list@boreham.org> +Subject: Re: Hardware/OS recommendations for large databases ( +Cc: pgsql-performance@postgresql.org +In-Reply-To: <437B578C.4000309@boreham.org> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <200511161550.jAGFoCY09049@candle.pha.pa.us> + <437B578C.4000309@boreham.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/324 +X-Sequence-Number: 15581 + +Just pick up a SCSI drive and a consumer ATA drive. + +Feel their weight. + +You don't have to look inside to tell the difference. + +Alex + +On 11/16/05, David Boreham <david_list@boreham.org> wrote: +> +> +> I suggest you read this on the difference between enterprise/SCSI and +> desktop/IDE drives: +> +> http://www.seagate.com/content/docs/pdf/whitepaper/D2c_More_than_Interfac= +e_ATA_vs_SCSI_042003.pdf +> +> +> This is exactly the kind of vendor propaganda I was talking about +> and it proves my point quite well : that there's nothing specific relati= +ng +> to reliability that is different between SCSI and SATA drives cited in t= +hat +> paper. +> It does have a bunch of FUD such as 'oh yeah we do a lot more +> drive characterization during manufacturing'. +> +> +> +> + +From pgsql-performance-owner@postgresql.org Thu Nov 17 15:54:57 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9EEABDB98A + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 15:54:55 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 08017-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 19:54:55 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.206]) + by svr1.postgresql.org (Postfix) with ESMTP id E32D5DB998 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 15:54:52 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id i28so473804wra + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 11:54:54 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=WkDdsQ7FqqO4zoLGZGNqNop4apT4rAaVon/3wG4Ne8dybeih7kmtks1bzxXAbRa6M4w9nIx5EURrSZyllgHig3bXP/Y4ViatlD30LprkjhSVMYepszxmzTuglsBHAukbc82iZPrPbJfKsJ9NgqdGPil7QhQM9H7dm1WSXFuFYe0= +Received: by 10.54.101.18 with SMTP id y18mr7419316wrb; + Thu, 17 Nov 2005 11:54:54 -0800 (PST) +Received: by 10.54.82.5 with HTTP; Thu, 17 Nov 2005 11:54:54 -0800 (PST) +Message-ID: <33c6269f0511171154t22e0bce0p803a1803f8b1a539@mail.gmail.com> +Date: Thu, 17 Nov 2005 14:54:54 -0500 +From: Alex Turner <armtuk@gmail.com> +To: "Joshua D. Drake" <jd@commandprompt.com> +Subject: Re: Hardware/OS recommendations for large databases ( +Cc: William Yu <wyu@talisys.com>, pgsql-performance@postgresql.org +In-Reply-To: <437B5859.9040805@commandprompt.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <dlfjgf$41b$1@news.hub.org> <437B5859.9040805@commandprompt.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/325 +X-Sequence-Number: 15582 + +On 11/16/05, Joshua D. Drake <jd@commandprompt.com> wrote: +> > +> > The only questions would be: +> > (1) Do you need a SMP server at all? I'd claim yes -- you always need +> > 2+ cores whether it's DC or 2P to avoid IO interrupts blocking other +> > processes from running. +> +> I would back this up. Even for smaller installations (single raid 1, 1 +> gig of ram). Why? Well because many applications are going to be CPU +> bound. For example +> we have a PHP application that is a CMS. On a single CPU machine, RAID 1 +> it takes about 300ms to deliver a single page, point to point. We are +> not IO bound. +> So what happens is that under reasonable load we are actually waiting +> for the CPU to process the code. +> + +This is the performance profile for PHP, not for Postgresql. This is +the postgresql mailing list. + +> A simple upgrade to an SMP machine literally doubles our performance +> because we are still not IO bound. I strongly suggest that everyone use +> at least a single dual core because of this experience. +> + +Performance of PHP, not postgresql. + +> > +> > (3) Do you need an insane amount of memory? Well here's the case where +> > the more expensive motherboard will serve you better since each CPU +> > slot has its own bank of memory. Spend more money on memory, get +> > cheaper single-core CPUs. +> Agreed. A lot of times the slowest dual-core is 5x what you actually +> need. So get the slowest, and bulk up on memory. If nothing else memory +> is cheap today and it might not be tomorrow. +[snip] + +Running postgresql on a single drive RAID 1 with PHP on the same +machine is not a typical installation. + +300ms for PHP in CPU time? wow dude - that's quite a page. PHP +typical can handle up to 30-50 pages per second for a typical OLTP +application on a single CPU box. Something is really wrong with that +system if it takes 300ms per page. + +Alex. + +From pgsql-performance-owner@postgresql.org Thu Nov 17 16:22:56 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 389E9DB9AE + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 16:22:55 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 09450-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 20:22:55 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by svr1.postgresql.org (Postfix) with ESMTP id 7A21CDB97D + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 16:22:50 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Thu, 17 Nov 2005 15:22:50 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD907@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases ( +Thread-Index: AcXrsSHF0O2OqsALTnO/xn1BVSgUUQAAmASQ +From: "Merlin Moncure" <merlin.moncure@rcsonline.com> +To: "Alex Turner" <armtuk@gmail.com> +Cc: <pgsql-performance@postgresql.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/326 +X-Sequence-Number: 15583 + +> Remember - large DB is going to be IO bound. Memory will get thrashed +> for file block buffers, even if you have large amounts, it's all gonna +> be cycled in and out again. + +'fraid I have to disagree here. I manage ERP systems for manufacturing +companies of various sizes. My systems are all completely cpu +bound...even though the larger database are well into two digit gigabyte +sizes, the data turnover while huge is relatively constrained and well +served by the O/S cache. OTOH, query latency is a *huge* factor and we +do everything possible to lower it. Even if the cpu is not 100% loaded, +faster processors make the application 'feel' faster to the client. + +Merlin + + + +From pgsql-performance-owner@postgresql.org Thu Nov 17 16:29:55 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6E163DB5B0 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 16:29:53 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 15121-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 20:29:53 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from toad.mtbrook.bozemanpass.com (toad.mtbrook.bozemanpass.com + [69.145.82.195]) + by svr1.postgresql.org (Postfix) with ESMTP id B2793DB466 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 16:29:50 -0400 (AST) +Received: from [69.145.82.218] (unknown [69.145.82.218]) + by toad.mtbrook.bozemanpass.com (Postfix) with ESMTP id BB51711027B + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 12:29:49 -0800 (PST) +Message-ID: <437CE847.3010101@boreham.org> +Date: Thu, 17 Nov 2005 13:29:59 -0700 +From: David Boreham <david_list@boreham.org> +Reply-To: david_list@boreham.org +User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <200511161550.jAGFoCY09049@candle.pha.pa.us> + <437B578C.4000309@boreham.org> + <33c6269f0511171150j24f2dd2bq607b69994338aa9@mail.gmail.com> +In-Reply-To: <33c6269f0511171150j24f2dd2bq607b69994338aa9@mail.gmail.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/327 +X-Sequence-Number: 15584 + +Alex Turner wrote: + +>Just pick up a SCSI drive and a consumer ATA drive. +> +>Feel their weight. +> +> +Not sure I get your point. We would want the lighter one, +all things being equal, right ? (lower shipping costs, less likely +to break when dropped on the floor....) + + + + + + +From pgsql-performance-owner@postgresql.org Thu Nov 17 16:34:18 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0B000DB982 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 16:34:17 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 15132-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 20:34:18 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from web33012.mail.mud.yahoo.com (web33012.mail.mud.yahoo.com + [68.142.206.76]) + by svr1.postgresql.org (Postfix) with SMTP id 7068CDB99F + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 16:34:15 -0400 (AST) +Received: (qmail 21805 invoked by uid 60001); 17 Nov 2005 20:34:16 -0000 +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; + h=Message-ID:Received:Date:From:Subject:To:MIME-Version:Content-Type:Content-Transfer-Encoding; + b=PK3XYaC1Qi4I0QWrOUtzX68QTxHaqJRHFU88fzcILE1zpaq2/8ZWJxMGLy15JAuGeTShmsm0+Ae8nX2a5cDdowENKALXQHoLZ0KLAOWbdooe+hPjThWUKAioMUUv3pRh47bn+QcRNBsa2YX6ADNxzGh6+8XJwPnCXyGCycdrmoA= + ; +Message-ID: <20051117203416.21803.qmail@web33012.mail.mud.yahoo.com> +Received: from [65.94.98.166] by web33012.mail.mud.yahoo.com via HTTP; + Thu, 17 Nov 2005 12:34:16 PST +Date: Thu, 17 Nov 2005 12:34:16 -0800 (PST) +From: Josel Malixi <jmalixi@yahoo.com> +Subject: unsubscribe +To: pgsql-performance@postgresql.org +MIME-Version: 1.0 +Content-Type: text/plain; charset=iso-8859-1 +Content-Transfer-Encoding: 8bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.479 required=5 tests=[DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.479 +X-Spam-Level: +X-Archive-Number: 200511/328 +X-Sequence-Number: 15585 + +unsubscribe + + + +__________________________________ +Yahoo! FareChase: Search multiple travel sites in one click. +http://farechase.yahoo.com + +From pgsql-performance-owner@postgresql.org Thu Nov 17 16:38:17 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id C95D6D6D07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 16:38:15 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 15905-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 20:38:16 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id CB728D7B8B + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 16:38:12 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id 80C3031059; Thu, 17 Nov 2005 21:38:13 +0100 (MET) +From: William Yu <wyu@talisys.com> +X-Newsgroups: pgsql.performance +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Thu, 17 Nov 2005 12:38:11 -0800 +Organization: Hub.Org Networking Services +Lines: 74 +Message-ID: <dlipnh$902$1@news.hub.org> +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <dlfjgf$41b$1@news.hub.org> + <33c6269f0511171148q7ea67482xd595ea5717956aa2@mail.gmail.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +User-Agent: Mozilla Thunderbird 1.0 (X11/20041206) +X-Accept-Language: en-us, en +In-Reply-To: <33c6269f0511171148q7ea67482xd595ea5717956aa2@mail.gmail.com> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[ADVANCE_FEE_1=0, AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/329 +X-Sequence-Number: 15586 + +Alex Turner wrote: +> Opteron 242 - $178.00 +> Opteron 242 - $178.00 +> Tyan S2882 - $377.50 +> Total: $733.50 +> +> Opteron 265 - $719.00 +> Tyan K8E - $169.00 +> Total: $888.00 + +You're comparing the wrong CPUs. The 265 is the 2x of the 244 so you'll +have to bump up the price more although not enough to make a difference. + +Looks like the price of the 2X MBs have dropped since I last looked at +it. Just a few months back, Tyan duals were $450-$500 which is what I +was basing my "priced less" statement from. + +> Tyan K8E - doesn't have any PCI-X, so it's also not apples to apples. +> Infact I couldn't find a single CPU slot board that did, so you pretty +> much have to buy a dual CPU board to get PCI-X. + +You can get single CPU boards w/ PCIe and use PCIe controller cards. +Probably expensive right now because they're so bleeding-edge new but +definitely on the downswing. + +> a) OLTP - probably IO bound, large number of queries/sec updating info +> on _disks_, not requiring much CPU activity except to retrieve item +> infomration which is well indexed and normalized. + +Not in my experience. I find on our OLTP servers, we run 98% in RAM and +hence are 100% CPU-bound. Our DB is about 50GB in size now, servers run +w/ 8GB of RAM. We were *very* CPU limited running 2x244. During busy +hours of the day, our avg "user transaction" time were jumping from +0.8sec to 1.3+sec. Did the 2x265 and now we're always in the 0.7sec to +0.9sec range. + +>>DC also gives you a better upgrade path. Let's say you do testing and +>>figure 2x246 is the right setup to handle the load. Well instead of +>>getting 2x1P, use the same 2P motherboard but only populate 1 CPU w/ a +>>DC/270. Now you have a server that can be upgraded to +80% more CPU by +>>popping in another DC/270 versus throwing out the entire thing to get a +>>4x1P setup. +> +> +> No argument there. But it's pointless if you are IO bound. + +Why would you just accept "we're IO bound, nothing we can do"? I'd do +everything in my power to make my app go from IO bound to CPU bound -- +whether by optimizing my code or buying more hardware. I can tell you if +our OLTP servers were IO bound, it would run like crap. Instead of < 1 +sec, we'd be looking at 5-10 seconds per "user transaction" and our +users would be screaming bloody murder. + +In theory, you can always convert your IO bound DB to CPU bound by +stuffing more and more RAM into your server. (Or partitioning the DB +across multiple servers.) Whether it's cost effective depends on the DB +and how much your users are paying you -- and that's a case-by-case +analysis. Not a global statement of "IO-bound, pointless". + +>>(2) Does a DC system perform better than it's Nx1P cousin? My experience +>>is yes. Did some rough tests in a drop-in-replacement 1x265 versus 2x244 +>>and saw about +10% for DC. All the official benchmarks (Spec, Java, SAP, +>>etc) from AMD/Sun/HP/IBM show DCs outperforming the Nx1P setups. +> +> +> Maybe true, but the 265 does have a 25% faster FSB than the 244, which +> might perhaps play a role. + +Nope. There's no such thing as FSB on Opterons. On-die memory controller +runs @ CPU speed and hence connects at whatever the memory runs at +(rounded off to some multiplier math). There's the HT speed that +controls the max IO bandwidth but that's based on the motherboard, not +the CPU. Plus the 265 and 244 both run at 1.8Ghz so the memory +multiplier & HT IO are both the same. + +From pgsql-performance-owner@postgresql.org Thu Nov 17 16:38:41 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 629A0DB98A + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 16:38:39 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14915-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 20:38:39 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from hosting.commandprompt.com (128.commandprompt.com + [207.173.200.128]) + by svr1.postgresql.org (Postfix) with ESMTP id 8E20EDB985 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 16:38:36 -0400 (AST) +Received: from [10.30.1.23] ([72.16.194.3]) (authenticated bits=0) + by hosting.commandprompt.com (8.13.4/8.13.4) with ESMTP id + jAHKXCrF007472; Thu, 17 Nov 2005 12:33:16 -0800 +Message-ID: <437CEA9B.6020401@commandprompt.com> +Date: Thu, 17 Nov 2005 12:39:55 -0800 +From: "Joshua D. Drake" <jd@commandprompt.com> +User-Agent: Thunderbird 1.5 (Windows/20051025) +MIME-Version: 1.0 +To: Alex Turner <armtuk@gmail.com> +CC: William Yu <wyu@talisys.com>, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <dlfjgf$41b$1@news.hub.org> <437B5859.9040805@commandprompt.com> + <33c6269f0511171154t22e0bce0p803a1803f8b1a539@mail.gmail.com> +In-Reply-To: <33c6269f0511171154t22e0bce0p803a1803f8b1a539@mail.gmail.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Greylist: Sender succeded SMTP AUTH authentication, not delayed by + milter-greylist-1.6 (hosting.commandprompt.com [192.168.1.101]); + Thu, 17 Nov 2005 12:33:16 -0800 (PST) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/330 +X-Sequence-Number: 15587 + + +>> So what happens is that under reasonable load we are actually waiting +>> for the CPU to process the code. +>> +>> +> +> This is the performance profile for PHP, not for Postgresql. This is +> the post +And your point? PostgreSQL benefits directly from what I am speaking +about as well. + +>> Performance of PHP, not postgresql. +>> +>> +Actually both. + +> [snip] +> +> Running postgresql on a single drive RAID 1 with PHP on the same +> machine is not a typical installation. +> +Want to bet? What do you think the majority of people hosting at +rackshack, rackspace, +superrack etc... are doing? Or how about all those virtual hosts? + +> 300ms for PHP in CPU time? wow dude - that's quite a page. PHP +> typical can handle up to 30-50 pages per second for a typical OLTP +> application on a single CPU box. Something is really wrong with that +> system if it takes 300ms per page. +> +There is wait time associated with that because we are hitting it with +50-100 connections at a time. + +Joshua D. Drake + +> Alex. +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 3: Have you checked our extensive FAQ? +> +> http://www.postgresql.org/docs/faq +> + + +From pgsql-performance-owner@postgresql.org Thu Nov 17 19:51:51 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 3D277D71C4 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 19:51:49 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 85431-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 23:51:51 +0000 (GMT) +X-Greylist: delayed 03:10:29.601869 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id ABB00DB1D4 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 19:51:45 -0400 (AST) +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr2.postgresql.org (Postfix) with ESMTP id B1103F0B4F + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 20:41:14 +0000 (GMT) +Received: from ram.rentec.com (mailhost [192.5.35.66]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jAHKemIN018282 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Thu, 17 Nov 2005 15:40:49 -0500 (EST) +X-Source: non-mednet +Received: from [172.26.132.145] (hoopoe.rentec.com [172.26.132.145]) + by ram.rentec.com (8.13.1/8.12.1) with ESMTP id jAHKeK02014568; + Thu, 17 Nov 2005 15:40:20 -0500 (EST) +Message-ID: <437CEAD5.1090106@rentec.com> +Date: Thu, 17 Nov 2005 15:40:53 -0500 +From: Alan Stange <stange@rentec.com> +Reply-To: stange@rentec.com +Organization: Renaissance Technologies Corp. +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: david_list@boreham.org, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <200511161550.jAGFoCY09049@candle.pha.pa.us> + <437B578C.4000309@boreham.org> + <33c6269f0511171150j24f2dd2bq607b69994338aa9@mail.gmail.com> + <437CE847.3010101@boreham.org> +In-Reply-To: <437CE847.3010101@boreham.org> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jAHKemIN018282 at Thu Nov 17 + 15:40:49 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/339 +X-Sequence-Number: 15596 + +David Boreham wrote: +> Alex Turner wrote: +> +>> Just pick up a SCSI drive and a consumer ATA drive. +>> +>> Feel their weight. +>> +>> +> Not sure I get your point. We would want the lighter one, +> all things being equal, right ? (lower shipping costs, less likely +> to break when dropped on the floor....) +Why would the lighter one be less likely to break when dropped on the floor? + +-- Alan + +From pgsql-performance-owner@postgresql.org Thu Nov 17 16:58:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id EED3FDB985 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 16:58:48 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 19485-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 20:58:49 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from zproxy.gmail.com (zproxy.gmail.com [64.233.162.193]) + by svr1.postgresql.org (Postfix) with ESMTP id 09A5EDB998 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 16:58:45 -0400 (AST) +Received: by zproxy.gmail.com with SMTP id x3so22639nzd + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 12:58:47 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; + b=bMk6fhrIIKdMvOq34pTVXdX6rb8TLGWCsNFXUDG81H9Kzyl8VQStuFGyIO62+XsRDdD0dlGNRu2YvGrKYuAqKvi4+vbPzIOAJVawbIT+jGS0PP3C/mReFPHLXcYFQLLfQ6W1CctTfbkDxb0EXdvFavm+UyDe7lstEUcktd5Tsis= +Received: by 10.64.131.4 with SMTP id e4mr7798847qbd; + Thu, 17 Nov 2005 12:58:46 -0800 (PST) +Received: by 10.64.243.11 with HTTP; Thu, 17 Nov 2005 12:58:46 -0800 (PST) +Message-ID: <38242de90511171258v22f334f3ua474a8aa99bdc29d@mail.gmail.com> +Date: Thu, 17 Nov 2005 13:58:46 -0700 +From: Joshua Marsh <icub3d@gmail.com> +To: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +In-Reply-To: <dlipnh$902$1@news.hub.org> +MIME-Version: 1.0 +Content-Type: multipart/alternative; + boundary="----=_Part_13115_5972285.1132261126498" +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <dlfjgf$41b$1@news.hub.org> + <33c6269f0511171148q7ea67482xd595ea5717956aa2@mail.gmail.com> + <dlipnh$902$1@news.hub.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[HTML_MESSAGE=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/332 +X-Sequence-Number: 15589 + +------=_Part_13115_5972285.1132261126498 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline + +On 11/17/05, William Yu <wyu@talisys.com> wrote: +> +> > No argument there. But it's pointless if you are IO bound. +> +> Why would you just accept "we're IO bound, nothing we can do"? I'd do +> everything in my power to make my app go from IO bound to CPU bound -- +> whether by optimizing my code or buying more hardware. I can tell you if +> our OLTP servers were IO bound, it would run like crap. Instead of < 1 +> sec, we'd be looking at 5-10 seconds per "user transaction" and our +> users would be screaming bloody murder. +> +> In theory, you can always convert your IO bound DB to CPU bound by +> stuffing more and more RAM into your server. (Or partitioning the DB +> across multiple servers.) Whether it's cost effective depends on the DB +> and how much your users are paying you -- and that's a case-by-case +> analysis. Not a global statement of "IO-bound, pointless". + + +We all want our systems to be CPU bound, but it's not always possible. +Remember, he is managing a 5 TB Databse. That's quite a bit different than = +a +100 GB or even 500 GB database. + +------=_Part_13115_5972285.1132261126498 +Content-Type: text/html; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline + +<br><div><span class=3D"gmail_quote">On 11/17/05, <b class=3D"gmail_sendern= +ame">William Yu</b> <<a href=3D"mailto:wyu@talisys.com">wyu@talisys.com<= +/a>> wrote:</span><blockquote class=3D"gmail_quote" style=3D"border-left= +: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1e= +x;"> +> No argument there.  But it's pointless if you are IO bound.<= +br><br>Why would you just accept "we're IO bound, nothing we can do&qu= +ot;? I'd do<br>everything in my power to make my app go from IO bound to CP= +U bound -- +<br>whether by optimizing my code or buying more hardware. I can tell you i= +f<br>our OLTP servers were IO bound, it would run like crap. Instead of <= +; 1<br>sec, we'd be looking at 5-10 seconds per "user transaction"= +; and our +<br>users would be screaming bloody murder.<br><br>In theory, you can alway= +s convert your IO bound DB to CPU bound by<br>stuffing more and more RAM in= +to your server. (Or partitioning the DB<br>across multiple servers.) Whethe= +r it's cost effective depends on the DB +<br>and how much your users are paying you -- and that's a case-by-case<br>= +analysis. Not a global statement of "IO-bound, pointless".</block= +quote><div><br> +We all want our systems to be CPU bound, but it's not always +possible.  Remember, he is managing a 5 TB Databse.  That's +quite a bit different than a 100 GB or even 500 GB database. <br> + </div><br></div> + +------=_Part_13115_5972285.1132261126498-- + +From pgsql-performance-owner@postgresql.org Thu Nov 17 17:02:44 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6BE00D71C6 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 17:02:42 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 27635-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 21:02:42 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from toad.mtbrook.bozemanpass.com (toad.mtbrook.bozemanpass.com + [69.145.82.195]) + by svr1.postgresql.org (Postfix) with ESMTP id C65ADD6D07 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 17:02:39 -0400 (AST) +Received: from [69.145.82.218] (unknown [69.145.82.218]) + by toad.mtbrook.bozemanpass.com (Postfix) with ESMTP id BC0CE11027B + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 13:02:41 -0800 (PST) +Message-ID: <437CEFFB.3060200@boreham.org> +Date: Thu, 17 Nov 2005 14:02:51 -0700 +From: David Boreham <david_list@boreham.org> +Reply-To: david_list@boreham.org +User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <200511161550.jAGFoCY09049@candle.pha.pa.us> + <437B578C.4000309@boreham.org> + <33c6269f0511171150j24f2dd2bq607b69994338aa9@mail.gmail.com> + <437CE847.3010101@boreham.org> <437CEAD5.1090106@rentec.com> +In-Reply-To: <437CEAD5.1090106@rentec.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/333 +X-Sequence-Number: 15590 + +Alan Stange wrote: + +>> Not sure I get your point. We would want the lighter one, +>> all things being equal, right ? (lower shipping costs, less likely +>> to break when dropped on the floor....) +> +> Why would the lighter one be less likely to break when dropped on the +> floor? + +They'd have less kinetic energy upon impact. + + + +From pgsql-performance-owner@postgresql.org Thu Nov 17 17:07:04 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A08D1DB9D6 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 17:07:03 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 26261-06-2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 21:07:04 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 20790DB9A7 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 17:06:58 -0400 (AST) +Received: from moonunit2.moonview.localnet (wsip-68-15-5-150.sd.sd.cox.net + [68.15.5.150]) + by svr2.postgresql.org (Postfix) with ESMTP id A57BFF0B59 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 21:07:00 +0000 (GMT) +Received: from [192.168.0.3] (moonunit3.moonview.localnet [192.168.0.3]) + by moonunit2.moonview.localnet (8.13.1/8.13.1) with ESMTP id + jAHLFNlw025202; Thu, 17 Nov 2005 13:15:23 -0800 +Message-ID: <437CF055.6020602@modgraph-usa.com> +Date: Thu, 17 Nov 2005 13:04:21 -0800 +From: "Craig A. James" <cjames@modgraph-usa.com> +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20050716) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Michael Fuhr <mike@fuhr.org> +Cc: Pgsql-Performance <pgsql-performance@postgresql.org> +Subject: Re: Perl DBD and an alarming problem +References: <BF9F6C0E.13B4A%llonergan@greenplum.com> + <1132136225.5711.4.camel@Panoramix> + <437B9DA9.2030806@modgraph-usa.com> + <20051117002344.GA55377@winnie.fuhr.org> +In-Reply-To: <20051117002344.GA55377@winnie.fuhr.org> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.095 required=5 tests=[AWL=0.095] +X-Spam-Score: 0.095 +X-Spam-Level: +X-Archive-Number: 200511/334 +X-Sequence-Number: 15591 + + +Thanks for the info on alarm and timeouts, this was a big help. One further comment: + +Michael Fuhr wrote: +>> eval { +>> local $SIG{ALRM} = sub {die("Timeout");}; +>> $time = gettimeofday; +>> alarm 20; +>> $sth = $dbh->prepare("a query that may take a long time..."); +>> $sth->execute(); +>> alarm 0; +>> }; +>> if ($@ && $@ =~ /Timeout/) { +>> my $elapsed = gettimeofday - $time; +>> print "Timed out after $elapsed seconds"; +>> } +>> +>>Now the mystery: It works, but it hardly matters what time I use for the +>>alarm call, the actual alarm event always happens at 26 seconds... +> +> +> High-level languages' signal handlers don't always work well with +> low-level libraries... +> +> Is there a reason you're using alarm() in the client instead of +> setting statement_timeout on the server? + +statement_timeout solved the problem, thanks VERY much for the pointer. To answer your question, I use alarm() because all the books and web references said that was how to do it. :-). I've used alarm() with Perl (with a 3rd-party C lib that had a potential infinite loop) very successfully. + +So thanks for the pointer to statement_timeout. But... + +When I set statement_timeout in the config file, it just didn't do anything - it never timed out (PG 8.0.3). I finally found in the documentation that I can do "set statement_timeout = xxx" from PerlDBI on a per-client basis, and that works. + +Craig + +From pgsql-performance-owner@postgresql.org Thu Nov 17 17:23:02 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8D152DBAD3 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 17:23:00 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 41187-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 21:23:00 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 5F56BDBA78 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 17:22:54 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id 10F0331059; Thu, 17 Nov 2005 22:22:56 +0100 (MET) +From: William Yu <wyu@talisys.com> +X-Newsgroups: pgsql.performance +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Thu, 17 Nov 2005 13:22:47 -0800 +Organization: Hub.Org Networking Services +Lines: 32 +Message-ID: <dlisba$fpf$1@news.hub.org> +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <dlfjgf$41b$1@news.hub.org> + <33c6269f0511171148q7ea67482xd595ea5717956aa2@mail.gmail.com> + <dlipnh$902$1@news.hub.org> + <38242de90511171258v22f334f3ua474a8aa99bdc29d@mail.gmail.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +User-Agent: Mozilla Thunderbird 1.0 (X11/20041206) +X-Accept-Language: en-us, en +In-Reply-To: <38242de90511171258v22f334f3ua474a8aa99bdc29d@mail.gmail.com> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/335 +X-Sequence-Number: 15592 + +Joshua Marsh wrote: +> +> On 11/17/05, *William Yu* <wyu@talisys.com <mailto:wyu@talisys.com>> wrote: +> +> > No argument there. But it's pointless if you are IO bound. +> +> Why would you just accept "we're IO bound, nothing we can do"? I'd do +> everything in my power to make my app go from IO bound to CPU bound -- +> whether by optimizing my code or buying more hardware. I can tell you if +> our OLTP servers were IO bound, it would run like crap. Instead of < 1 +> sec, we'd be looking at 5-10 seconds per "user transaction" and our +> users would be screaming bloody murder. +> +> In theory, you can always convert your IO bound DB to CPU bound by +> stuffing more and more RAM into your server. (Or partitioning the DB +> across multiple servers.) Whether it's cost effective depends on the DB +> and how much your users are paying you -- and that's a case-by-case +> analysis. Not a global statement of "IO-bound, pointless". +> +> +> We all want our systems to be CPU bound, but it's not always possible. +> Remember, he is managing a 5 TB Databse. That's quite a bit different +> than a 100 GB or even 500 GB database. + +I did say "in theory". :) I'm pretty sure google is more CPU bound than +IO bound -- they just spread their DB over 50K servers or whatever. Not +everybody is willing to pay for that but it's always in the realm of +plausibility. + +Plus we have to go back to the statement I was replying to which was "I +have yet to come across a DB system that wasn't IO bound". + + +From pgsql-performance-owner@postgresql.org Thu Nov 17 18:19:54 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id E4BB1DB9B5 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 18:13:16 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 69201-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 22:13:18 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtp100.rog.mail.re2.yahoo.com (smtp100.rog.mail.re2.yahoo.com + [206.190.36.78]) + by svr1.postgresql.org (Postfix) with SMTP id 26434DB96C + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 18:13:13 -0400 (AST) +Received: (qmail 40787 invoked from network); 17 Nov 2005 22:13:15 -0000 +Received: from unknown (HELO phlogiston.dydns.org) + (a.sullivan@rogers.com@209.222.54.227 with login) + by smtp100.rog.mail.re2.yahoo.com with SMTP; 17 Nov 2005 22:13:15 -0000 +Received: by phlogiston.dydns.org (Postfix, from userid 1000) + id 764414109; Thu, 17 Nov 2005 17:13:14 -0500 (EST) +Date: Thu, 17 Nov 2005 17:13:14 -0500 +From: Andrew Sullivan <ajs@crankycanuck.ca> +To: pgsql-performance@postgresql.org +Subject: Re: weird performances problem +Message-ID: <20051117221314.GC26696@phlogiston.dyndns.org> +References: <437CC21D.8070402@openwide.fr> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <437CC21D.8070402@openwide.fr> +User-Agent: Mutt/1.5.9i +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/336 +X-Sequence-Number: 15593 + +On Thu, Nov 17, 2005 at 06:47:09PM +0100, Guillaume Smet wrote: +> queries are executed fast even if they are complicated but sometimes and +> for half an hour, we have a general slow down. + +Is it exactly half an hour? What changes at the time that happens +(i.e. what else happens on the machine?). Is this a time, for +example, when logrotate is killing your I/O with file moves? + +A +-- +Andrew Sullivan | ajs@crankycanuck.ca +I remember when computers were frustrating because they *did* exactly what +you told them to. That actually seems sort of quaint now. + --J.D. Baldwin + +From pgsql-performance-owner@postgresql.org Thu Nov 17 19:29:03 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id E85FAD71A8 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 19:29:01 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 82521-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 23:29:03 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from tigger.fuhr.org (tigger.fuhr.org [63.214.45.158]) + by svr1.postgresql.org (Postfix) with ESMTP id 2B943DB98D + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 19:28:58 -0400 (AST) +Received: from winnie.fuhr.org (winnie.fuhr.org [10.1.0.1]) + by tigger.fuhr.org (8.13.3/8.13.3) with ESMTP id jAHNSwZX049688 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); + Thu, 17 Nov 2005 16:29:00 -0700 (MST) + (envelope-from mfuhr@winnie.fuhr.org) +Received: from winnie.fuhr.org (localhost [127.0.0.1]) + by winnie.fuhr.org (8.13.4/8.13.4) with ESMTP id jAHNSvR4050568; + Thu, 17 Nov 2005 16:28:57 -0700 (MST) + (envelope-from mfuhr@winnie.fuhr.org) +Received: (from mfuhr@localhost) + by winnie.fuhr.org (8.13.4/8.13.4/Submit) id jAHNSvdR050567; + Thu, 17 Nov 2005 16:28:57 -0700 (MST) (envelope-from mfuhr) +Date: Thu, 17 Nov 2005 16:28:57 -0700 +From: Michael Fuhr <mike@fuhr.org> +To: "Craig A. James" <cjames@modgraph-usa.com> +Cc: Pgsql-Performance <pgsql-performance@postgresql.org> +Subject: Re: Perl DBD and an alarming problem +Message-ID: <20051117232857.GA49910@winnie.fuhr.org> +References: <BF9F6C0E.13B4A%llonergan@greenplum.com> + <1132136225.5711.4.camel@Panoramix> + <437B9DA9.2030806@modgraph-usa.com> + <20051117002344.GA55377@winnie.fuhr.org> + <437CF055.6020602@modgraph-usa.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <437CF055.6020602@modgraph-usa.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/337 +X-Sequence-Number: 15594 + +On Thu, Nov 17, 2005 at 01:04:21PM -0800, Craig A. James wrote: +> When I set statement_timeout in the config file, it just didn't do anything +> - it never timed out (PG 8.0.3). I finally found in the documentation that +> I can do "set statement_timeout = xxx" from PerlDBI on a per-client basis, +> and that works. + +You probably shouldn't set statement_timeout on a global basis +anyway, but did you reload the server after you made the change? +Setting statement_timeout in postgresql.conf and then reloading the +server works here in 8.0.4. + +-- +Michael Fuhr + +From pgsql-performance-owner@postgresql.org Thu Nov 17 19:39:42 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 3856EDB9EA + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 19:35:12 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 83256-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 23:35:12 +0000 (GMT) +X-Greylist: delayed 05:47:55.442799 by SQLgrey- +Received: from soufre.accelance.net (soufre.accelance.net [213.162.48.15]) + by svr1.postgresql.org (Postfix) with ESMTP id 34533DB996 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 19:35:06 -0400 (AST) +Received: from [86.200.101.246] (ALyon-254-1-66-246.w86-200.abo.wanadoo.fr + [86.200.101.246]) + (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) + (No client certificate requested) + by soufre.accelance.net (Postfix) with ESMTP id 7CDC05DD2; + Fri, 18 Nov 2005 00:35:08 +0100 (CET) +Message-ID: <437D13AA.4010309@openwide.fr> +Date: Fri, 18 Nov 2005 00:35:06 +0100 +From: Guillaume Smet <guillaume.smet@openwide.fr> +User-Agent: Mozilla Thunderbird 1.0.6-1.1.fc3 (X11/20050720) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Andrew Sullivan <ajs@crankycanuck.ca> +CC: pgsql-performance@postgresql.org +Subject: Re: weird performances problem +References: <437CC21D.8070402@openwide.fr> + <20051117221314.GC26696@phlogiston.dyndns.org> +In-Reply-To: <20051117221314.GC26696@phlogiston.dyndns.org> +X-Enigmail-Version: 0.89.6.0 +X-Enigmail-Supports: pgp-inline, pgp-mime +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/338 +X-Sequence-Number: 15595 + +Andrew, + +Andrew Sullivan wrote: + > Is it exactly half an hour? What changes at the time that happens + > (i.e. what else happens on the machine?). Is this a time, for + > example, when logrotate is killing your I/O with file moves? + +No, it's not exactly half an hour. It's just that it slows down for some +time (10, 20, 30 minutes) and then it's OK again. It happens several +times per day. I checked if there are other processes running when we +have this slow down but it's not the case. +There's not really a difference between when it's OK or not (apart from +the number of connections because the db is too slow): load is still at +4 or 5, iowait is still at 0%, there's still cpu idle and we still have +free memory. I can't find what is the limit and why there is cpu idle. + +I forgot to give our non default postgresql.conf parameters: +shared_buffers = 28800 +sort_mem = 32768 +vacuum_mem = 32768 +max_fsm_pages = 350000 +max_fsm_relations = 2000 +checkpoint_segments = 16 +effective_cache_size = 270000 +random_page_cost = 2 + +Thanks for your help + +-- +Guillaume + +From pgsql-performance-owner@postgresql.org Thu Nov 17 20:22:16 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5C2EFDB9AD + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 20:15:28 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 87380-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 00:15:30 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from zproxy.gmail.com (zproxy.gmail.com [64.233.162.193]) + by svr1.postgresql.org (Postfix) with ESMTP id AD0ADDBA00 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 20:15:25 -0400 (AST) +Received: by zproxy.gmail.com with SMTP id z3so55969nzf + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 16:15:28 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=qITIMSdlJRNqYFWXCfyQ1LqLZ64xl+V0ulBSmriB61/AXW+ISRD0QFzX3nQoC/QRGhi/93wR4qJhGlmfpRskRsaablpKCXeOeFFTEDEIYKs3xmVrJNCOns3TPUOQHfDaQG9acsKI8s5I0Ape3/O8+0HCb2dYIqSGSjFeEfzSBBg= +Received: by 10.65.191.13 with SMTP id t13mr274719qbp; + Thu, 17 Nov 2005 16:15:28 -0800 (PST) +Received: by 10.65.192.16 with HTTP; Thu, 17 Nov 2005 16:15:28 -0800 (PST) +Message-ID: <b41c75520511171615g7c0fe923l@mail.gmail.com> +Date: Fri, 18 Nov 2005 01:15:28 +0100 +From: Claus Guttesen <kometen@gmail.com> +To: Guillaume Smet <guillaume.smet@openwide.fr> +Subject: Re: weird performances problem +Cc: Andrew Sullivan <ajs@crankycanuck.ca>, pgsql-performance@postgresql.org +In-Reply-To: <437D13AA.4010309@openwide.fr> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <437CC21D.8070402@openwide.fr> + <20051117221314.GC26696@phlogiston.dyndns.org> + <437D13AA.4010309@openwide.fr> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/340 +X-Sequence-Number: 15597 + +> I forgot to give our non default postgresql.conf parameters: +> shared_buffers =3D 28800 +> sort_mem =3D 32768 +> vacuum_mem =3D 32768 +> max_fsm_pages =3D 350000 +> max_fsm_relations =3D 2000 +> checkpoint_segments =3D 16 +> effective_cache_size =3D 270000 +> random_page_cost =3D 2 + +Isn't sort_mem quite high? Remember that sort_mem size is allocated +for each sort, not for each connection. Mine is 4096 (4 MB). My +effective_cache_size is set to 27462. + +What OS are you running? + +regards +Claus + +From pgsql-performance-owner@postgresql.org Thu Nov 17 21:35:36 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 001F2DAC73 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 21:35:34 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 96448-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 01:35:37 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 0A6D4D9506 + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 21:35:31 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id A12B531059; Fri, 18 Nov 2005 02:35:35 +0100 (MET) +From: Ron Mayer <rm_pg@cheapcomplexdevices.com> +X-Newsgroups: pgsql.performance +Subject: Re: Help speeding up delete +Date: Thu, 17 Nov 2005 17:39:48 -0800 +Organization: Hub.Org Networking Services +Lines: 30 +Message-ID: <437D30E4.3080500@cheapcomplexdevices.com> +References: <43790A99.9050603@noao.edu> <4162.1132011763@sss.pgh.pa.us> + <1132171206.4959.60.camel@localhost.localdomain> + <437BDF22.9030109@familyhealth.com.au> +Mime-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +To: Christopher Kings-Lynne <chriskl@familyhealth.com.au> +User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) +X-Accept-Language: en-us, en +In-Reply-To: <437BDF22.9030109@familyhealth.com.au> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/341 +X-Sequence-Number: 15598 + +Christopher Kings-Lynne wrote: +>>> +>>> Quite seriously, if you're still using 7.2.4 for production purposes +>>> you could justifiably be accused of negligence.... +>> +>> Perhaps we should put a link on the home page underneath LATEST RELEASEs +>> saying +>> 7.2: de-supported +>> with a link to a scary note along the lines of the above. +> +> I strongly support an explicit desupported notice for 7.2 and below on +> the website... + + +I'd go so far as to say the version #s of supported versions +is one of pieces of information I'd most expect to see on +the main support page ( http://www.postgresql.org/support/ ). + +Perhaps it'd be nice to even show a table like + Version Released On Support Ends + 7.1 4 BC Sep 3 1752 + 7.2 Feb 31 1900 Jan 0 2000 + 7.4 2003-11-17 At least 2005-x-x + 8.0 2005-01-19 At least 2006-x-x +with a footnote saying that only the most recent dot release +of each family is considered supported. + +It also might be nice to have a footnote saying that any +of the commercical support companies might support the older +versions for longer periods of time. + +From pgsql-performance-owner@postgresql.org Thu Nov 17 21:50:59 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 825DDDB726 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 21:50:57 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 09259-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 01:51:00 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from houston.familyhealth.com.au (houston.au.fhnetwork.com + [203.22.197.21]) + by svr1.postgresql.org (Postfix) with ESMTP id 356FFDB71D + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 21:50:53 -0400 (AST) +Received: from houston.familyhealth.com.au (localhost [127.0.0.1]) + by houston.familyhealth.com.au (Postfix) with ESMTP id AD0DA25079; + Fri, 18 Nov 2005 09:50:56 +0800 (WST) +Received: from [127.0.0.1] (work-40.internal [192.168.0.40]) + by houston.familyhealth.com.au (Postfix) with ESMTP id 2877D25078; + Fri, 18 Nov 2005 09:50:51 +0800 (WST) +Message-ID: <437D34CC.9080200@familyhealth.com.au> +Date: Fri, 18 Nov 2005 09:56:28 +0800 +From: Christopher Kings-Lynne <chriskl@familyhealth.com.au> +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: "Steinar H. Gunderson" <sgunderson@bigfoot.com> +Cc: pgsql-performance@postgresql.org +Subject: Re: Help speeding up delete +References: <43790A99.9050603@noao.edu> <4162.1132011763@sss.pgh.pa.us> + <1132171206.4959.60.camel@localhost.localdomain> + <437BDF9A.4060700@familyhealth.com.au> + <20051117111927.GB26459@uio.no> + <437C9CBE.8020907@familyhealth.com.au> + <20051117172511.GA28121@uio.no> +In-Reply-To: <20051117172511.GA28121@uio.no> +Content-Type: text/plain; charset=UTF-8; format=flowed +Content-Transfer-Encoding: 7bit +X-familyhealth-MailScanner-Information: Please contact the ISP for more + information +X-familyhealth-MailScanner: Found to be clean +X-familyhealth-MailScanner-From: chriskl@familyhealth.com.au +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.02 required=5 tests=[AWL=0.020] +X-Spam-Score: 0.02 +X-Spam-Level: +X-Archive-Number: 200511/342 +X-Sequence-Number: 15599 + +> I do not really see why all the distributions could do something like this, +> instead of mucking around with special statically compiled pg_dumps and the +> like... + +Contrib modules and tablespaces. + +Plus, no version of pg_dump before 8.0 is able to actually perform such +reliable dumps and reloads (due to bugs). However, that's probably moot +these days. + +Chris + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 01:37:27 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id E4781D78B6 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 17 Nov 2005 23:46:34 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 34867-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 03:46:38 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from tigger.fuhr.org (tigger.fuhr.org [63.214.45.158]) + by svr1.postgresql.org (Postfix) with ESMTP id 2C7FED719A + for <pgsql-performance@postgresql.org>; + Thu, 17 Nov 2005 23:46:31 -0400 (AST) +Received: from winnie.fuhr.org (winnie.fuhr.org [10.1.0.1]) + by tigger.fuhr.org (8.13.3/8.13.3) with ESMTP id jAI3kWQ1049884 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); + Thu, 17 Nov 2005 20:46:34 -0700 (MST) + (envelope-from mfuhr@winnie.fuhr.org) +Received: from winnie.fuhr.org (localhost [127.0.0.1]) + by winnie.fuhr.org (8.13.4/8.13.4) with ESMTP id jAI3kVRJ070282; + Thu, 17 Nov 2005 20:46:31 -0700 (MST) + (envelope-from mfuhr@winnie.fuhr.org) +Received: (from mfuhr@localhost) + by winnie.fuhr.org (8.13.4/8.13.4/Submit) id jAI3kVGM070281; + Thu, 17 Nov 2005 20:46:31 -0700 (MST) (envelope-from mfuhr) +Date: Thu, 17 Nov 2005 20:46:31 -0700 +From: Michael Fuhr <mike@fuhr.org> +To: "Craig A. James" <cjames@modgraph-usa.com> +Cc: pgsql-performance@postgresql.org +Subject: Re: Perl DBD and an alarming problem +Message-ID: <20051118034631.GA70159@winnie.fuhr.org> +References: <BF9F6C0E.13B4A%llonergan@greenplum.com> + <1132136225.5711.4.camel@Panoramix> + <437B9DA9.2030806@modgraph-usa.com> + <20051117002344.GA55377@winnie.fuhr.org> + <437CF055.6020602@modgraph-usa.com> + <20051117232857.GA49910@winnie.fuhr.org> + <437D3085.9040207@modgraph-usa.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <437D3085.9040207@modgraph-usa.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/345 +X-Sequence-Number: 15602 + +[Please copy the mailing list on replies.] + +On Thu, Nov 17, 2005 at 05:38:13PM -0800, Craig A. James wrote: +> >You probably shouldn't set statement_timeout on a global basis +> >anyway +> +> The server is a "one trick pony" so setting a global timeout value is +> actually appropriate. + +Beware that statement_timeout also applies to maintenance commands +like VACUUM; it might be more appropriate to set per-user timeouts +with ALTER USER. If you do set a global timeout then you might +want to set a per-user timeout of 0 for database superusers so +maintenance activities don't get timed out. + +> >... but did you reload the server after you made the change? +> >Setting statement_timeout in postgresql.conf and then reloading the +> >server works here in 8.0.4. +> +> Yes. By "reload" I assume you mean restarting it from scratch. + +Either a restart or a "pg_ctl reload", which sends a SIGHUP to the +server. You can effect some changes by sending a signal to a running +server without having to restart it entirely. + +> In this case, I use +> +> /etc/init.d/postgresql restart +> +> It definitely had no effect at all. I tried values clear down to 1 +> millisecond, but the server never timed out for any query. + +Did you use "SHOW statement_timeout" to see if the value was set +to what you wanted? Are you sure you edited the right file? As a +database superuser execute "SHOW config_file" to see what file the +server is using. What exactly did the line look like after you +changed it? + +-- +Michael Fuhr + +From pgsql-performance-owner@postgresql.org Fri Nov 18 01:16:19 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id E5019D719A + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 00:58:55 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 43077-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 04:58:54 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from stark.xeocode.com (stark.xeocode.com [216.58.44.227]) + by svr1.postgresql.org (Postfix) with ESMTP id 7D6F5DB7B0 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 00:58:53 -0400 (AST) +Received: from localhost ([127.0.0.1] helo=stark.xeocode.com) + by stark.xeocode.com with smtp (Exim 3.36 #1 (Debian)) + id 1EcyKj-00071r-00; Thu, 17 Nov 2005 23:58:45 -0500 +To: Joshua Marsh <icub3d@gmail.com> +Cc: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <dlfjgf$41b$1@news.hub.org> + <33c6269f0511171148q7ea67482xd595ea5717956aa2@mail.gmail.com> + <dlipnh$902$1@news.hub.org> + <38242de90511171258v22f334f3ua474a8aa99bdc29d@mail.gmail.com> +In-Reply-To: <38242de90511171258v22f334f3ua474a8aa99bdc29d@mail.gmail.com> +From: Greg Stark <gsstark@mit.edu> +Organization: The Emacs Conspiracy; member since 1992 +Date: 17 Nov 2005 23:58:45 -0500 +Message-ID: <873blur1q2.fsf@stark.xeocode.com> +Lines: 14 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/343 +X-Sequence-Number: 15600 + + +Joshua Marsh <icub3d@gmail.com> writes: + +> We all want our systems to be CPU bound, but it's not always possible. + +Sure it is, let me introduce you to my router, a 486DX100... + + + +Ok, I guess that wasn't very helpful, I admit. + + +-- +greg + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 01:23:24 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6A285DB7B0 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 01:17:21 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 45057-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 05:17:19 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from stark.xeocode.com (stark.xeocode.com [216.58.44.227]) + by svr1.postgresql.org (Postfix) with ESMTP id AB0F5DB745 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 01:17:18 -0400 (AST) +Received: from localhost ([127.0.0.1] helo=stark.xeocode.com) + by stark.xeocode.com with smtp (Exim 3.36 #1 (Debian)) + id 1Ecycd-0007EV-00; Fri, 18 Nov 2005 00:17:15 -0500 +To: Joshua Marsh <icub3d@gmail.com> +Cc: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com> + <33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com> + <dlfjgf$41b$1@news.hub.org> + <33c6269f0511171148q7ea67482xd595ea5717956aa2@mail.gmail.com> + <dlipnh$902$1@news.hub.org> + <38242de90511171258v22f334f3ua474a8aa99bdc29d@mail.gmail.com> +In-Reply-To: <38242de90511171258v22f334f3ua474a8aa99bdc29d@mail.gmail.com> +From: Greg Stark <gsstark@mit.edu> +Organization: The Emacs Conspiracy; member since 1992 +Date: 18 Nov 2005 00:17:15 -0500 +Message-ID: <87zmo2pmas.fsf@stark.xeocode.com> +Lines: 19 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/344 +X-Sequence-Number: 15601 + + +Joshua Marsh <icub3d@gmail.com> writes: + +> We all want our systems to be CPU bound, but it's not always possible. +> Remember, he is managing a 5 TB Databse. That's quite a bit different than a +> 100 GB or even 500 GB database. + +Ok, a more productive point: it's not really the size of the database that +controls whether you're I/O bound or CPU bound. It's the available I/O +bandwidth versus your CPU speed. + +If your I/O subsystem can feed data to your CPU as fast as it can consume it +then you'll be CPU bound no matter how much data you have in total. It's +harder to scale up I/O subsystems than CPUs, instead of just replacing a CPU +it tends to mean replacing the whole system to get a better motherboard with a +faster, better bus, as well as adding more controllers and more disks. + +-- +greg + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 02:08:05 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B69A2DB4C2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 02:08:03 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 47937-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 06:08:02 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw01.mi8.com [63.240.6.47]) + by svr1.postgresql.org (Postfix) with ESMTP id C3423DA387 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 02:08:00 -0400 (AST) +Received: from 172.16.1.110 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D1)); Fri, 18 Nov 2005 01:07:55 -0500 +X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 01:07:55 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 01:07:54 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Thu, 17 Nov 2005 22:07:54 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Greg Stark" <gsstark@mit.edu>, + "Joshua Marsh" <icub3d@gmail.com> +cc: pgsql-performance@postgresql.org +Message-ID: <BFA2AFBA.13FC4%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsARNdwzQ0YbPFQJC9u/hNHCb98wABVaAV +In-Reply-To: <87zmo2pmas.fsf@stark.xeocode.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 18 Nov 2005 06:07:55.0088 (UTC) + FILETIME=[6A835D00:01C5EC06] +X-WSS-ID: 6F63B03121G13205170-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[AWL=0.000, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/346 +X-Sequence-Number: 15603 + +Greg, + + +On 11/17/05 9:17 PM, "Greg Stark" <gsstark@mit.edu> wrote: + +> Ok, a more productive point: it's not really the size of the database that +> controls whether you're I/O bound or CPU bound. It's the available I/O +> bandwidth versus your CPU speed. + +Postgres + Any x86 CPU from 2.4GHz up to Opteron 280 is CPU bound after +110MB/s of I/O. This is true of Postgres 7.4, 8.0 and 8.1. + +A $1,000 system with one CPU and two SATA disks in a software RAID0 will +perform exactly the same as a $80,000 system with 8 dual core CPUs and the +world's best SCSI RAID hardware on a large database for decision support +(what the poster asked about). + +Regards, + +- Luke + + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 08:58:48 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id EF79DDB985 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 08:58:45 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 16590-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 12:58:47 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from net2.micro-automation.com (net2.micro-automation.com + [64.7.141.29]) + by svr1.postgresql.org (Postfix) with SMTP id 841DADB9E7 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 08:58:40 -0400 (AST) +Received: (qmail 15708 invoked from network); 18 Nov 2005 12:58:44 -0000 +Received: from dcdsl.ebox.com (HELO ?192.168.1.2?) (davec@64.7.143.116) + by net2.micro-automation.com with SMTP; 18 Nov 2005 12:58:44 -0000 +In-Reply-To: <33c6269f0511171150j24f2dd2bq607b69994338aa9@mail.gmail.com> +References: <200511161550.jAGFoCY09049@candle.pha.pa.us> + <437B578C.4000309@boreham.org> + <33c6269f0511171150j24f2dd2bq607b69994338aa9@mail.gmail.com> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: <012EB91C-667A-495F-B4F2-F14EE7162ABA@fastcrypt.com> +Cc: David Boreham <david_list@boreham.org>, + pgsql-performance@postgresql.org +Content-Transfer-Encoding: 7bit +From: Dave Cramer <pg@fastcrypt.com> +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Fri, 18 Nov 2005 07:58:43 -0500 +To: Alex Turner <armtuk@gmail.com> +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/347 +X-Sequence-Number: 15604 + + +On 17-Nov-05, at 2:50 PM, Alex Turner wrote: + +> Just pick up a SCSI drive and a consumer ATA drive. +> +> Feel their weight. +> +> You don't have to look inside to tell the difference. +At one point stereo manufacturers put weights in the case just to +make them heavier. +The older ones weighed more and the consumer liked heavy stereos. + +Be careful what you measure. + +Dave +> +> Alex +> +> On 11/16/05, David Boreham <david_list@boreham.org> wrote: +>> +>> +>> I suggest you read this on the difference between enterprise/SCSI +>> and +>> desktop/IDE drives: +>> +>> http://www.seagate.com/content/docs/pdf/whitepaper/ +>> D2c_More_than_Interface_ATA_vs_SCSI_042003.pdf +>> +>> +>> This is exactly the kind of vendor propaganda I was talking about +>> and it proves my point quite well : that there's nothing specific +>> relating +>> to reliability that is different between SCSI and SATA drives +>> cited in that +>> paper. +>> It does have a bunch of FUD such as 'oh yeah we do a lot more +>> drive characterization during manufacturing'. +>> +>> +>> +>> +> +> ---------------------------(end of +> broadcast)--------------------------- +> TIP 9: In versions below 8.0, the planner will ignore your desire to +> choose an index scan if your joining column's datatypes do not +> match +> + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 09:00:16 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id E2D9ADB8C6 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 09:00:13 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 17733-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 13:00:16 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from net2.micro-automation.com (net2.micro-automation.com + [64.7.141.29]) + by svr1.postgresql.org (Postfix) with SMTP id 026AEDB77A + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 09:00:10 -0400 (AST) +Received: (qmail 15714 invoked from network); 18 Nov 2005 13:00:14 -0000 +Received: from dcdsl.ebox.com (HELO ?192.168.1.2?) (davec@64.7.143.116) + by net2.micro-automation.com with SMTP; 18 Nov 2005 13:00:14 -0000 +In-Reply-To: <BFA2AFBA.13FC4%llonergan@greenplum.com> +References: <BFA2AFBA.13FC4%llonergan@greenplum.com> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: <0F3B99E2-4575-42B8-8AAC-3FE4B231348C@fastcrypt.com> +Cc: "Greg Stark" <gsstark@mit.edu>, "Joshua Marsh" <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Content-Transfer-Encoding: 7bit +From: Dave Cramer <pg@fastcrypt.com> +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Fri, 18 Nov 2005 08:00:17 -0500 +To: Luke Lonergan <llonergan@greenplum.com> +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/348 +X-Sequence-Number: 15605 + + +On 18-Nov-05, at 1:07 AM, Luke Lonergan wrote: + +> Greg, +> +> +> On 11/17/05 9:17 PM, "Greg Stark" <gsstark@mit.edu> wrote: +> +>> Ok, a more productive point: it's not really the size of the +>> database that +>> controls whether you're I/O bound or CPU bound. It's the available +>> I/O +>> bandwidth versus your CPU speed. +> +> Postgres + Any x86 CPU from 2.4GHz up to Opteron 280 is CPU bound +> after +> 110MB/s of I/O. This is true of Postgres 7.4, 8.0 and 8.1. +> +> A $1,000 system with one CPU and two SATA disks in a software RAID0 +> will +> perform exactly the same as a $80,000 system with 8 dual core CPUs +> and the +> world's best SCSI RAID hardware on a large database for decision +> support +> (what the poster asked about). + +Now there's an interesting line drawn in the sand. I presume you have +numbers to back this up ? + +This should draw some interesting posts. + +Dave +> +> Regards, +> +> - Luke +> +> +> +> ---------------------------(end of +> broadcast)--------------------------- +> TIP 9: In versions below 8.0, the planner will ignore your desire to +> choose an index scan if your joining column's datatypes do not +> match +> + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 09:22:45 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id DFF1EDB985 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 09:22:42 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 17605-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 13:22:45 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.metronet.co.uk (mail.metronet.co.uk [213.162.97.75]) + by svr1.postgresql.org (Postfix) with ESMTP id 5DD6ADB9FA + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 09:22:39 -0400 (AST) +Received: from mainbox.archonet.com + (84-51-143-99.archon037.adsl.metronet.co.uk [84.51.143.99]) + by smtp.metronet.co.uk (MetroNet Mail) with ESMTP + id CAE77434448; Fri, 18 Nov 2005 13:22:33 +0000 (GMT) +Received: from [192.168.1.17] (client17.office.archonet.com [192.168.1.17]) + by mainbox.archonet.com (Postfix) with ESMTP id 1261D15EA4; + Fri, 18 Nov 2005 13:22:42 +0000 (GMT) +Message-ID: <437DD5A1.1090605@archonet.com> +Date: Fri, 18 Nov 2005 13:22:41 +0000 +From: Richard Huxton <dev@archonet.com> +User-Agent: Mozilla Thunderbird 1.0.7 (X11/20051013) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Dave Cramer <pg@fastcrypt.com> +Cc: Luke Lonergan <llonergan@greenplum.com>, + Greg Stark <gsstark@mit.edu>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA2AFBA.13FC4%llonergan@greenplum.com> + <0F3B99E2-4575-42B8-8AAC-3FE4B231348C@fastcrypt.com> +In-Reply-To: <0F3B99E2-4575-42B8-8AAC-3FE4B231348C@fastcrypt.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/349 +X-Sequence-Number: 15606 + +Dave Cramer wrote: +> +> On 18-Nov-05, at 1:07 AM, Luke Lonergan wrote: +> +>> Postgres + Any x86 CPU from 2.4GHz up to Opteron 280 is CPU bound after +>> 110MB/s of I/O. This is true of Postgres 7.4, 8.0 and 8.1. +>> +>> A $1,000 system with one CPU and two SATA disks in a software RAID0 will +>> perform exactly the same as a $80,000 system with 8 dual core CPUs +>> and the +>> world's best SCSI RAID hardware on a large database for decision support +>> (what the poster asked about). +> +> +> Now there's an interesting line drawn in the sand. I presume you have +> numbers to back this up ? +> +> This should draw some interesting posts. + +Well, I'm prepared to swap Luke *TWO* $1000 systems for one $80,000 +system if he's got one going :-) + +-- + Richard Huxton + Archonet Ltd + +From pgsql-performance-owner@postgresql.org Fri Nov 18 13:31:54 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 71566DB985 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 09:30:53 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 20717-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 13:30:55 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw01.mi8.com [63.240.6.47]) + by svr1.postgresql.org (Postfix) with ESMTP id E83FDDB9F2 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 09:30:49 -0400 (AST) +Received: from 172.16.1.110 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D1)); Fri, 18 Nov 2005 08:30:37 -0500 +X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 08:30:37 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 08:30:36 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 05:30:34 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Richard Huxton" <dev@archonet.com>, + "Dave Cramer" <pg@fastcrypt.com> +cc: "Greg Stark" <gsstark@mit.edu>, "Joshua Marsh" <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Message-ID: <BFA3177A.14008%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsQzAxqdsQTWT6QCueM+k0hrU5HAAARCrh +In-Reply-To: <437DD5A1.1090605@archonet.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 18 Nov 2005 13:30:37.0387 (UTC) + FILETIME=[42E089B0:01C5EC44] +X-WSS-ID: 6F6308F721G13412697-01-01 +Content-Type: multipart/alternative; + boundary=B_3215136635_1770200 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[AWL=-0.000, + HTML_MESSAGE=0.001, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/360 +X-Sequence-Number: 15617 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3215136635_1770200 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Richard, + +On 11/18/05 5:22 AM, "Richard Huxton" <dev@archonet.com> wrote: + +> Well, I'm prepared to swap Luke *TWO* $1000 systems for one $80,000 +> system if he's got one going :-) + +Finally, a game worth playing! + +Except it=B9s backward =AD I=B9ll show you 80 $1,000 systems performing 80 times +faster than one $80,000 system. + +On your proposition =AD I don=B9t have any $80,000 systems for trade, do you? + +- Luke + +--B_3215136635_1770200 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +<HTML> +<HEAD> +<TITLE>Re: [PERFORM] Hardware/OS recommendations for large databases (</TIT= +LE> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Richa= +rd,<BR> +<BR> +On 11/18/05 5:22 AM, "Richard Huxton" <dev@archonet.com> wr= +ote:<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>Well, I'm prepared to swap Luke *TWO* $1000 systems for= + one $80,000<BR> +system if he's got one going :-)<BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'><BR> +Finally, a game worth playing!<BR> +<BR> +Except it’s backward – I’ll show you 80 $1,000 systems pe= +rforming 80 times faster than one $80,000 system.<BR> +<BR> +On your proposition – I don’t have any $80,000 systems for trad= +e, do you?<BR> +<BR> +- Luke</SPAN></FONT> +</BODY> +</HTML> + + +--B_3215136635_1770200-- + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 12:25:45 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 710BCDB985 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 09:42:15 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 21424-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 13:42:17 +0000 (GMT) +X-Greylist: delayed 17:01:00.223893 by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id 63DE9DB965 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 09:42:11 -0400 (AST) +Received: from ram.rentec.com (mailhost [192.5.35.66]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jAIDftn9018179 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Fri, 18 Nov 2005 08:41:57 -0500 (EST) +X-Source: non-mednet +Received: from [172.26.132.145] (hoopoe.rentec.com [172.26.132.145]) + by ram.rentec.com (8.13.1/8.12.1) with ESMTP id jAIDfNr0018317; + Fri, 18 Nov 2005 08:41:23 -0500 (EST) +Message-ID: <437DDA26.4000603@rentec.com> +Date: Fri, 18 Nov 2005 08:41:58 -0500 +From: Alan Stange <stange@rentec.com> +Reply-To: stange@rentec.com +Organization: Renaissance Technologies Corp. +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +CC: Dave Cramer <pg@fastcrypt.com>, Luke Lonergan <llonergan@greenplum.com>, + Greg Stark <gsstark@mit.edu>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA2AFBA.13FC4%llonergan@greenplum.com> + <0F3B99E2-4575-42B8-8AAC-3FE4B231348C@fastcrypt.com> + <437DD5A1.1090605@archonet.com> +In-Reply-To: <437DD5A1.1090605@archonet.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jAIDftn9018179 at Fri Nov 18 + 08:41:57 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.095 required=5 tests=[AWL=-0.095, + MISSING_HEADERS=0.189] +X-Spam-Score: 0.095 +X-Spam-Level: +X-Archive-Number: 200511/359 +X-Sequence-Number: 15616 + +Richard Huxton wrote: +> Dave Cramer wrote: +>> +>> On 18-Nov-05, at 1:07 AM, Luke Lonergan wrote: +>> +>>> Postgres + Any x86 CPU from 2.4GHz up to Opteron 280 is CPU bound +>>> after +>>> 110MB/s of I/O. This is true of Postgres 7.4, 8.0 and 8.1. +>>> +>>> A $1,000 system with one CPU and two SATA disks in a software RAID0 +>>> will +>>> perform exactly the same as a $80,000 system with 8 dual core CPUs +>>> and the +>>> world's best SCSI RAID hardware on a large database for decision +>>> support +>>> (what the poster asked about). +>> +>> +>> Now there's an interesting line drawn in the sand. I presume you +>> have numbers to back this up ? +>> +>> This should draw some interesting posts. + +That's interesting, as I occasionally see more than 110MB/s of +postgresql IO on our system. I'm using a 32KB block size, which has +been a huge win in performance for our usage patterns. 300GB database +with a lot of turnover. A vacuum analyze now takes about 3 hours, which +is much shorter than before. Postgresql 8.1, dual opteron, 8GB memory, +Linux 2.6.11, FC drives. + +-- Alan + +From pgsql-performance-owner@postgresql.org Fri Nov 18 12:20:39 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 3C2A0DBA26 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 09:47:07 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 20961-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 13:47:09 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw02.mi8.com [63.240.6.46]) + by svr1.postgresql.org (Postfix) with ESMTP id 50BF4DBA5F + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 09:47:03 -0400 (AST) +Received: from 172.16.1.112 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D2)); Fri, 18 Nov 2005 08:47:00 -0500 +X-Server-Uuid: 7829E76E-BB9E-4995-8473-3C0929DF7DD1 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 08:47:00 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 08:46:59 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 05:46:58 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: stange@rentec.com +cc: "Dave Cramer" <pg@fastcrypt.com>, "Greg Stark" <gsstark@mit.edu>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-ID: <BFA31B52.14012%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsReV45/v76ff9T2yQxgfgf3wdzwAAKXmW +In-Reply-To: <437DDA26.4000603@rentec.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 18 Nov 2005 13:47:00.0177 (UTC) + FILETIME=[8CAA6410:01C5EC46] +X-WSS-ID: 6F6304DE2RS9387233-03-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.253 required=5 tests=[AWL=0.000, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.253 +X-Spam-Level: * +X-Archive-Number: 200511/358 +X-Sequence-Number: 15615 + +Alan, + +On 11/18/05 5:41 AM, "Alan Stange" <stange@rentec.com> wrote: + +> +> That's interesting, as I occasionally see more than 110MB/s of +> postgresql IO on our system. I'm using a 32KB block size, which has +> been a huge win in performance for our usage patterns. 300GB database +> with a lot of turnover. A vacuum analyze now takes about 3 hours, which +> is much shorter than before. Postgresql 8.1, dual opteron, 8GB memory, +> Linux 2.6.11, FC drives. + +300GB / 3 hours = 27MB/s. + +If you are using the 2.6 linux kernel, you may be fooled into thinking you +burst more than you actually get in net I/O because the I/O stats changed in +tools like iostat and vmstat. + +The only meaningful stats are (size of data) / (time to process data). Do a +sequential scan of one of your large tables that you know the size of, then +divide by the run time and report it. + +I'm compiling some new test data to make my point now. + +Regards, + +- Luke + + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 12:00:33 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 865CADBA64 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 09:47:43 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 22119-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 13:47:42 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from net2.micro-automation.com (net2.micro-automation.com + [64.7.141.29]) + by svr1.postgresql.org (Postfix) with SMTP id 12B46DBA26 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 09:47:36 -0400 (AST) +Received: (qmail 15951 invoked from network); 18 Nov 2005 13:47:41 -0000 +Received: from dcdsl.ebox.com (HELO ?192.168.1.2?) (davec@64.7.143.116) + by net2.micro-automation.com with SMTP; 18 Nov 2005 13:47:41 -0000 +In-Reply-To: <BFA3177A.14008%llonergan@greenplum.com> +References: <BFA3177A.14008%llonergan@greenplum.com> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: multipart/alternative; boundary=Apple-Mail-52--604358616 +Message-Id: <B06243D5-43B8-4D4F-A065-A000C2BD7207@fastcrypt.com> +Cc: "Richard Huxton" <dev@archonet.com>, "Greg Stark" <gsstark@mit.edu>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +From: Dave Cramer <pg@fastcrypt.com> +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Fri, 18 Nov 2005 08:47:43 -0500 +To: Luke Lonergan <llonergan@greenplum.com> +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[AWL=-0.000, + HTML_MESSAGE=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/354 +X-Sequence-Number: 15611 + + +--Apple-Mail-52--604358616 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/plain; + charset=WINDOWS-1252; + delsp=yes; + format=flowed + + +On 18-Nov-05, at 8:30 AM, Luke Lonergan wrote: + +> Richard, +> +> On 11/18/05 5:22 AM, "Richard Huxton" <dev@archonet.com> wrote: +> +>> Well, I'm prepared to swap Luke *TWO* $1000 systems for one $80,000 +>> system if he's got one going :-) +> +> Finally, a game worth playing! +> +> Except it=92s backward =96 I=92ll show you 80 $1,000 systems = +performing =20 +> 80 times faster than one $80,000 system. +Now you wouldn't happen to be selling a system that would enable this =20= + +for postgres, now would ya ? +> +> On your proposition =96 I don=92t have any $80,000 systems for trade, =20= + +> do you? +> +> - Luke + + +--Apple-Mail-52--604358616 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/html; + charset=WINDOWS-1252 + +<HTML><BODY style=3D"word-wrap: break-word; -khtml-nbsp-mode: space; = +-khtml-line-break: after-white-space; "><BR><DIV><DIV>On 18-Nov-05, at = +8:30 AM, Luke Lonergan wrote:</DIV><BR = +class=3D"Apple-interchange-newline"><BLOCKQUOTE type=3D"cite"> <FONT = +face=3D"Verdana, Helvetica, Arial"><SPAN = +style=3D"font-size:14.0px">Richard,<BR> <BR> On 11/18/05 5:22 AM, = +"Richard Huxton" <<A = +href=3D"mailto:dev@archonet.com">dev@archonet.com</A>> wrote:<BR> = +<BR> </SPAN></FONT><BLOCKQUOTE type=3D"cite"><FONT face=3D"Verdana, = +Helvetica, Arial"><SPAN style=3D"font-size:14.0px">Well, I'm prepared to = +swap Luke *TWO* $1000 systems for one $80,000<BR> system if he's got one = +going :-)<BR> </SPAN></FONT></BLOCKQUOTE><FONT face=3D"Verdana, = +Helvetica, Arial"><SPAN style=3D"font-size:14.0px"><BR> Finally, a game = +worth playing!<BR> <BR> Except it=92s backward =96 I=92ll show you 80 = +$1,000 systems performing 80 times faster than one $80,000 = +system.<BR></SPAN></FONT></BLOCKQUOTE>Now you wouldn't happen to be = +selling a system that would enable this for postgres, now would ya = +?<BR><BLOCKQUOTE type=3D"cite"><FONT face=3D"Verdana, Helvetica, = +Arial"><SPAN style=3D"font-size:14.0px"> <BR> On your proposition =96 I = +don=92t have any $80,000 systems for trade, do you?<BR> <BR> - = +Luke</SPAN></FONT> </BLOCKQUOTE></DIV><BR></BODY></HTML>= + +--Apple-Mail-52--604358616-- + +From pgsql-performance-owner@postgresql.org Fri Nov 18 11:36:51 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 2E7CEDBA5F + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 10:04:59 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 25064-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 14:05:01 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id 23503DB77A + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 10:04:55 -0400 (AST) +Received: from 172.16.1.112 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Fri, 18 Nov 2005 09:04:47 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 09:04:25 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 09:04:24 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 06:04:24 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Dave Cramer" <pg@fastcrypt.com> +cc: "Greg Stark" <gsstark@mit.edu>, "Joshua Marsh" <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Message-ID: <BFA31F68.14017%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsQAi9HGMh4pFwSiam1ZsLnxnClAACPIaY +In-Reply-To: <0F3B99E2-4575-42B8-8AAC-3FE4B231348C@fastcrypt.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 18 Nov 2005 14:04:25.0376 (UTC) + FILETIME=[FBA71A00:01C5EC48] +X-WSS-ID: 6F6300E531S14414958-23-01 +Content-Type: multipart/alternative; + boundary=B_3215138664_1920020 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[AWL=-0.000, + HTML_MESSAGE=0.001, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/352 +X-Sequence-Number: 15609 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3215138664_1920020 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Dave, + + +On 11/18/05 5:00 AM, "Dave Cramer" <pg@fastcrypt.com> wrote: +>=20 +> Now there's an interesting line drawn in the sand. I presume you have +> numbers to back this up ? +>=20 +> This should draw some interesting posts. + +OK, here we go: + +The $1,000 system (System A): + +- I bought 16 of these in 2003 for $1,200 each. They have Intel or Asus +motherboards, Intel P4 3.0GHz CPUs with an 800MHz FSB. They have a system +drive and two RAID0 SATA drives, the Western Digital 74GB Raptor (10K RPM). +They have 1GB of RAM. + +* A test of write and read performance on the RAID0: + +> [llonergan@kite4 raid0]$ time dd if=3D/dev/zero of=3Dbigfile bs=3D8k count=3D2500= +00 +> 250000+0 records in +> 250000+0 records out +>=20 +> real 0m17.453s +> user 0m0.249s +> sys 0m10.246s + +> [llonergan@kite4 raid0]$ time dd if=3Dbigfile of=3D/dev/null bs=3D8k +> 250000+0 records in +> 250000+0 records out +>=20 +> real 0m18.930s +> user 0m0.130s +> sys 0m3.590s + +> So, the write performance is 114MB/s and read performance is 106MB/s. + +The $6,000 system (System B): + +* I just bought 5 of these systems for $6,000 each. They are dual Opteron +systems with 8GB of RAM and 2x 250 model CPUs, which are close to the +fastest. They have the new 3Ware 9550SX SATA RAID adapters coupled to +Western Digital 400GB RE2 model hard drives. They are organized as a RAID5= +. + +* A test of write and read performance on the RAID5: + +> [root@modena2 dbfast1]# time dd if=3D/dev/zero of=3Dbigfile bs=3D8k count=3D20000= +00 +> 2000000+0 records in +> 2000000+0 records out +>=20 +> real 0m51.441s +> user 0m0.288s +> sys 0m29.119s +>=20 +> [root@modena2 dbfast1]# time dd if=3Dbigfile of=3D/dev/null bs=3D8k +> 2000000+0 records in +> 2000000+0 records out +>=20 +> real 0m39.605s +> user 0m0.244s +> sys 0m19.207s +>=20 +> So, the write performance is 314MB/s and read performance is 404MB/s (!) = + This +> is the fastest I=B9ve seen 8 disk drives perform. +>=20 +So, the question is: which of these systems (A or B) can scan a large table +faster using non-MPP postgres? How much faster would you wager? + +Send your answer, and I=B9ll post the result. + +Regards, + +- Luke + +--B_3215138664_1920020 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +<HTML> +<HEAD> +<TITLE>Re: [PERFORM] Hardware/OS recommendations for large databases (</TIT= +LE> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Dave,= +<BR> +<BR> +<BR> +On 11/18/05 5:00 AM, "Dave Cramer" <pg@fastcrypt.com> wrote= +:<BR> +<FONT COLOR=3D"#0000FF">> <BR> +> Now there's an interesting line drawn in the sand. I presume you have = +<BR> +> numbers to back this up ?<BR> +> <BR> +> This should draw some interesting posts.<BR> +</FONT><BR> +OK, here we go:<BR> +<BR> +The $1,000 system (System A):<BR> +<BR> +- I bought 16 of these in 2003 for $1,200 each. They have Intel or Asus mot= +herboards, Intel P4 3.0GHz CPUs with an 800MHz FSB.  They have a system= + drive and two RAID0 SATA drives, the Western Digital 74GB Raptor (10K RPM).= +  They have 1GB of RAM.<BR> +<BR> +</SPAN></FONT><UL><LI><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'f= +ont-size:14.0px'>A test of write and read performance on the RAID0:<BR> +</SPAN></FONT></UL><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font= +-size:14.0px'><BR> +</SPAN></FONT><BLOCKQUOTE><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Courie= +r New">[llonergan@kite4 raid0]$ time dd if=3D/dev/zero of=3Dbigfile bs=3D8k count=3D= +250000<BR> +250000+0 records in<BR> +250000+0 records out<BR> +<BR> +real    0m17.453s<BR> +user    0m0.249s<BR> +sys     0m10.246s<BR> +</FONT></SPAN></BLOCKQUOTE><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Verda= +na, Helvetica, Arial"><BR> +</FONT></SPAN><BLOCKQUOTE><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Courie= +r New">[llonergan@kite4 raid0]$ time dd if=3Dbigfile of=3D/dev/null bs=3D8k<BR> +250000+0 records in<BR> +250000+0 records out<BR> +<BR> +real    0m18.930s<BR> +user    0m0.130s<BR> +sys     0m3.590s<BR> +</FONT></SPAN></BLOCKQUOTE><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Verda= +na, Helvetica, Arial"><BR> +</FONT></SPAN><BLOCKQUOTE><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Verdan= +a, Helvetica, Arial">So, the write performance is 114MB/s and read performan= +ce is 106MB/s.<BR> +</FONT></SPAN></BLOCKQUOTE><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Verda= +na, Helvetica, Arial"><BR> +The $6,000 system (System B):<BR> +<BR> +</FONT></SPAN><UL><LI><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Verdana, H= +elvetica, Arial">I just bought 5 of these systems for $6,000 each.  The= +y are dual Opteron systems with 8GB of RAM and 2x 250 model CPUs, which are = +close to the fastest.  They have the new 3Ware 9550SX SATA RAID adapter= +s coupled to  Western Digital 400GB RE2 model hard drives.  They a= +re organized as a RAID5.<BR> +</FONT></SPAN></UL><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Verdana, Helv= +etica, Arial"><BR> +</FONT></SPAN><UL><LI><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Verdana, H= +elvetica, Arial">A test of write and read performance on the RAID5:<BR> +</FONT></SPAN></UL><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Verdana, Helv= +etica, Arial"><BR> +</FONT></SPAN><BLOCKQUOTE><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Courie= +r New">[root@modena2 dbfast1]# time dd if=3D/dev/zero of=3Dbigfile bs=3D8k count=3D2= +000000<BR> +2000000+0 records in<BR> +2000000+0 records out<BR> +<BR> +real    0m51.441s<BR> +user    0m0.288s<BR> +sys     0m29.119s<BR> +<BR> +[root@modena2 dbfast1]# time dd if=3Dbigfile of=3D/dev/null bs=3D8k<BR> +2000000+0 records in<BR> +2000000+0 records out<BR> +<BR> +real    0m39.605s<BR> +user    0m0.244s<BR> +sys     0m19.207s<BR> +<BR> +</FONT><FONT FACE=3D"Verdana, Helvetica, Arial">So, the write performance is = +314MB/s and read performance is 404MB/s (!)  This is the fastest I̵= +7;ve seen 8 disk drives perform.<BR> +<BR> +</FONT></SPAN></BLOCKQUOTE><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Verda= +na, Helvetica, Arial">So, the question is: which of these systems (A or B) c= +an scan a large table faster using non-MPP postgres?  How much faster w= +ould you wager?<BR> +<BR> +Send your answer, and I’ll post the result.<BR> +<BR> +Regards,<BR> +<BR> +- Luke</FONT></SPAN> +</BODY> +</HTML> + + +--B_3215138664_1920020-- + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 10:56:26 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6F5D4DB8FD + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 10:47:50 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 26659-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 14:47:53 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id C7C98DB77A + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 10:47:47 -0400 (AST) +Received: from ram.rentec.com (mailhost [192.5.35.66]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jAIEkoVE020786 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Fri, 18 Nov 2005 09:46:51 -0500 (EST) +X-Source: non-mednet +Received: from [172.26.132.145] (hoopoe.rentec.com [172.26.132.145]) + by ram.rentec.com (8.13.1/8.12.1) with ESMTP id jAIEkK7Y025463; + Fri, 18 Nov 2005 09:46:20 -0500 (EST) +Message-ID: <437DE960.9070606@rentec.com> +Date: Fri, 18 Nov 2005 09:46:56 -0500 +From: Alan Stange <stange@rentec.com> +Reply-To: stange@rentec.com +Organization: Renaissance Technologies Corp. +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Luke Lonergan <llonergan@greenplum.com> +CC: Dave Cramer <pg@fastcrypt.com>, Greg Stark <gsstark@mit.edu>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA31B52.14012%llonergan@greenplum.com> +In-Reply-To: <BFA31B52.14012%llonergan@greenplum.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jAIEkoVE020786 at Fri Nov 18 + 09:46:51 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.032 required=5 tests=[AWL=0.032] +X-Spam-Score: 0.032 +X-Spam-Level: +X-Archive-Number: 200511/350 +X-Sequence-Number: 15607 + +Luke Lonergan wrote: +> Alan, +> +> On 11/18/05 5:41 AM, "Alan Stange" <stange@rentec.com> wrote: +> +> +>> That's interesting, as I occasionally see more than 110MB/s of +>> postgresql IO on our system. I'm using a 32KB block size, which has +>> been a huge win in performance for our usage patterns. 300GB database +>> with a lot of turnover. A vacuum analyze now takes about 3 hours, which +>> is much shorter than before. Postgresql 8.1, dual opteron, 8GB memory, +>> Linux 2.6.11, FC drives. +>> +> +> 300GB / 3 hours = 27MB/s. +> +That's 3 hours under load, with 80 compute clients beating on the +database at the same time. We have the stats turned way up, so the +analyze tends to read a big chunk of the tables a second time as +well. We typically don't have three hours a day of idle time. + +-- Alan + +From pgsql-performance-owner@postgresql.org Fri Nov 18 11:41:15 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0F1A8DBAAE + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 11:01:01 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 27132-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 15:01:03 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtpauth06.mail.atl.earthlink.net + (smtpauth06.mail.atl.earthlink.net [209.86.89.66]) + by svr1.postgresql.org (Postfix) with ESMTP id B36A1DBAA4 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 11:00:57 -0400 (AST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; + d=earthlink.net; + b=ga4fEG4e5dsrDnq72MTJ8fd2V1p6p77SNd5+kb440/DDvkRjKf3Dm+VchHBUchAg; + h=Received:Message-Id:X-Mailer:Date:To:From:Subject:In-Reply-To:References:Mime-Version:Content-Type:X-ELNK-Trace:X-Originating-IP; +Received: from [71.243.20.20] (helo=ron-6d52adff2a6.earthlink.net) + by smtpauth06.mail.atl.earthlink.net with asmtp (Exim 4.34) + id 1Ed7jZ-00061e-BO; Fri, 18 Nov 2005 10:01:01 -0500 +Message-Id: <6.2.5.6.0.20051118092018.03b6cba0@earthlink.net> +X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6 +Date: Fri, 18 Nov 2005 10:00:56 -0500 +To: "Luke Lonergan" <llonergan@greenplum.com>, + pgsql-performance@postgresql.org +From: Ron <rjpeace@earthlink.net> +Subject: Re: Hardware/OS recommendations for large databases +In-Reply-To: <BFA2AFBA.13FC4%llonergan@greenplum.com> +References: <87zmo2pmas.fsf@stark.xeocode.com> + <BFA2AFBA.13FC4%llonergan@greenplum.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset="us-ascii"; format=flowed +X-ELNK-Trace: + acd68a6551193be5d780f4a490ca69563f9fea00a6dd62bcea7568f56d9b8dfc9f309d8278238e95350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c +X-Originating-IP: 71.243.20.20 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.479 required=5 tests=[DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.479 +X-Spam-Level: +X-Archive-Number: 200511/353 +X-Sequence-Number: 15610 + +While I agree with you in principle that pg becomes CPU bound +relatively easily compared to other DB products (at ~110-120MBps +according to a recent thread), there's a bit of hyperbole in your post. + +a. There's a big difference between the worst performing 1C x86 ISA +CPU available and the best performing 2C one (IIRC, that's the +2.4GHz, 1MB L2 cache AMDx2 4800+ as of this writing) + +b. Two 2C CPU's vs one 1C CPU means that a pg process will almost +never be waiting on other non pg processes. It also means that 3-4 +pg processes, CPU bound or not, can execute in parallel. Not an +option with one 1C CPU. + +c. Mainboards with support for multiple CPUs and lots' of RAM are +_not_ the cheap ones. + +d. No one should ever use RAID 0 for valuable data. Ever. So at +the least you need 4 HD's for a RAID 10 set (RAID 5 is not a good +option unless write performance is unimportant. 4HD RAID 5 is +particularly not a good option.) + +e. The server usually needs to talk to things over a network +connection. Often performance here matters. Mainboards with 2 1GbE +NICs and/or PCI-X (or PCI-E) slots for 10GbE cards are not the cheap ones. + +f. Trash HDs mean poor IO performance and lower reliability. While +TOTL 15Krpm 4Gb FC HDs are usually overkill (Not always. It depends +on context.), +you at least want SATA II HDs with NCQ or TCQ support. And you want +them to have a decent media warranty- preferably a 5 year one if you +can get it. Again, these are not the cheapest HD's available. + +g. Throughput limitations say nothing about latency +considerations. OLTP-like systems _want_ HD spindles. AMAP. Even +non OLTP-like systems need a fair number of spindles to optimize HD +IO: dedicated WAL set, multiple dedicated DB sets, dedicated OS and +swap space set, etc, etc. At 50MBps ASTR, you need 16 HD's operating +in parallel to saturate the bandwidth of a PCI-X channel. +That's ~8 independent pg tasks (queries using different tables, +dedicated WAL IO, etc) running in parallel. Regardless of application domain. + +h. Decent RAID controllers and HBAs are not cheap either. Even SW +RAID benefits from having a big dedicated RAM buffer to talk to. + +While the above may not cost you $80K, it sure isn't costing you $1K either. +Maybe ~$15-$20K, but not $1K. + +Ron + + +At 01:07 AM 11/18/2005, Luke Lonergan wrote: +>Greg, +> +> +>On 11/17/05 9:17 PM, "Greg Stark" <gsstark@mit.edu> wrote: +> +> > Ok, a more productive point: it's not really the size of the database that +> > controls whether you're I/O bound or CPU bound. It's the available I/O +> > bandwidth versus your CPU speed. +> +>Postgres + Any x86 CPU from 2.4GHz up to Opteron 280 is CPU bound after +>110MB/s of I/O. This is true of Postgres 7.4, 8.0 and 8.1. +> +>A $1,000 system with one CPU and two SATA disks in a software RAID0 will +>perform exactly the same as a $80,000 system with 8 dual core CPUs and the +>world's best SCSI RAID hardware on a large database for decision support +>(what the poster asked about). +> +>Regards, +> +>- Luke +> +> +> +>---------------------------(end of broadcast)--------------------------- +>TIP 9: In versions below 8.0, the planner will ignore your desire to +> choose an index scan if your joining column's datatypes do not +> match + + + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 11:24:02 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 262AFD82C0 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 11:13:56 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 30513-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 15:13:59 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw01.mi8.com [63.240.6.47]) + by svr1.postgresql.org (Postfix) with ESMTP id 17DBAD6D50 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 11:13:52 -0400 (AST) +Received: from 172.16.1.110 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D1)); Fri, 18 Nov 2005 10:13:43 -0500 +X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 10:13:43 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 10:13:42 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 07:13:42 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Dave Cramer" <pg@fastcrypt.com> +cc: "Greg Stark" <gsstark@mit.edu>, "Joshua Marsh" <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Message-ID: <BFA32FA6.14027%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsQAi9HGMh4pFwSiam1ZsLnxnClAAEqB0s +In-Reply-To: <0F3B99E2-4575-42B8-8AAC-3FE4B231348C@fastcrypt.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 18 Nov 2005 15:13:43.0481 (UTC) + FILETIME=[AA139290:01C5EC52] +X-WSS-ID: 6F63302D21G13482411-01-01 +Content-Type: multipart/alternative; + boundary=B_3215142822_2162763 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[AWL=-0.000, + HTML_MESSAGE=0.001, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/351 +X-Sequence-Number: 15608 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3215142822_2162763 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Dave, + +On 11/18/05 5:00 AM, "Dave Cramer" <pg@fastcrypt.com> wrote: +>=20 +> Now there's an interesting line drawn in the sand. I presume you have +> numbers to back this up ? +>=20 +> This should draw some interesting posts. + +Part 2: The answer + +System A: +> This system is running RedHat 3 Update 4, with a Fedora 2.6.10 Linux kern= +el. +>=20 +> On a single table with 15 columns (the Bizgres IVP) at a size double memo= +ry +> (2.12GB), Postgres 8.0.3 with Bizgres enhancements takes 32 seconds to sc= +an +> the table: that=B9s 66 MB/s. Not the efficiency I=B9d hope from the onboard = +SATA +> controller that I=B9d like, I would have expected to get 85% of the 100MB/s= + raw +> read performance. +>=20 +> So that=B9s $1,200 / 66 MB/s (without adjusting for 2003 price versus now) = +=3D +> 18.2 $/MB/s +>=20 +> Raw data: +> [llonergan@kite4 IVP]$ cat scan.sh +> #!/bin/bash +>=20 +> time psql -c "select count(*) from ivp.bigtable1" dgtestdb +> [llonergan@kite4 IVP]$ cat sysout1 +> count =20 +> ---------- +> 10000000 +> (1 row) +>=20 +>=20 +> real 0m32.565s +> user 0m0.002s +> sys 0m0.003s +>=20 +> Size of the table data: +> [llonergan@kite4 IVP]$ du -sk dgtestdb/base +> 2121648 dgtestdb/base +>=20 +System B: +> This system is running an XFS filesystem, and has been tuned to use very = +large +> (16MB) readahead. It=B9s running the Centos 4.1 distro, which uses a Linux +> 2.6.9 kernel. +>=20 +> Same test as above, but with 17GB of data takes 69.7 seconds to scan (!) +> That=B9s 244.2MB/s, which is obviously double my earlier point of 110-120MB= +/s. +> This system is running with a 16MB Linux readahead setting, let=B9s try it = +with +> the default (I think) setting of 256KB =AD AHA! Now we get 171.4 seconds or +> 99.3MB/s. +>=20 +> So, using the tuned setting of =B3blockdev =8Bsetra 16384=B2 we get $6,000 / 24= +4MB/s +> =3D 24.6 $/MB/s +> If we use the default Linux setting it=B9s 2.5x worse. +>=20 +> Raw data: +> [llonergan@modena2 IVP]$ cat scan.sh +> #!/bin/bash +>=20 +> time psql -c "select count(*) from ivp.bigtable1" dgtestdb +> [llonergan@modena2 IVP]$ cat sysout3 +> count =20 +> ---------- +> 80000000 +> (1 row) +>=20 +>=20 +> real 1m9.875s +> user 0m0.000s +> sys 0m0.004s +> [llonergan@modena2 IVP]$ !du +> du -sk dgtestdb/base +> 17021260 dgtestdb/base + +Summary: + +<cough, cough> OK =AD you can get more I/O bandwidth out of the current I/O +path for sequential scan if you tune the filesystem for large readahead. +This is a cheap alternative to overhauling the executor to use asynch I/O. + +Still, there is a CPU limit here =AD this is not I/O bound, it is CPU limited +as evidenced by the sensitivity to readahead settings. If the filesystem +could do 1GB/s, you wouldn=B9t go any faster than 244MB/s. + +- Luke + +--B_3215142822_2162763 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +<HTML> +<HEAD> +<TITLE>Re: [PERFORM] Hardware/OS recommendations for large databases (</TIT= +LE> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Dave,= +<BR> +<BR> +On 11/18/05 5:00 AM, "Dave Cramer" <pg@fastcrypt.com> wrote= +:<BR> +<FONT COLOR=3D"#0000FF">> <BR> +> Now there's an interesting line drawn in the sand. I presume you have = +<BR> +> numbers to back this up ?<BR> +> <BR> +> This should draw some interesting posts.<BR> +</FONT><BR> +Part 2: The answer<BR> +<BR> +System A:<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>This system is running RedHat 3 Update 4, with a Fedora= + 2.6.10 Linux kernel.<BR> +<BR> +On a single table with 15 columns (the Bizgres IVP) at a size double memory= + (2.12GB), Postgres 8.0.3 with Bizgres enhancements takes 32 seconds to scan= + the table: that’s 66 MB/s.  Not the efficiency I’d hope fr= +om the onboard SATA controller that I’d like, I would have expected to= + get 85% of the 100MB/s raw read performance.<BR> +<BR> +So that’s $1,200 / 66 MB/s (without adjusting for 2003 price versus n= +ow) =3D 18.2 $/MB/s<BR> +<BR> +Raw data:<BR> +</SPAN></FONT><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Courier New">[llon= +ergan@kite4 IVP]$ cat scan.sh <BR> +#!/bin/bash<BR> +<BR> +time psql -c "select count(*) from ivp.bigtable1" dgtestdb<BR> +[llonergan@kite4 IVP]$ cat sysout1<BR> +  count   <BR> +----------<BR> + 10000000<BR> +(1 row)<BR> +<BR> +<BR> +real    0m32.565s<BR> +user    0m0.002s<BR> +sys     0m0.003s<BR> +<BR> +Size of the table data:<BR> +[llonergan@kite4 IVP]$ du -sk dgtestdb/base<BR> +2121648 dgtestdb/base<BR> +</FONT><FONT FACE=3D"Verdana, Helvetica, Arial"><BR> +</FONT></SPAN></BLOCKQUOTE><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Verda= +na, Helvetica, Arial">System B:<BR> +</FONT></SPAN><BLOCKQUOTE><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Verdan= +a, Helvetica, Arial">This system is running an XFS filesystem, and has been = +tuned to use very large (16MB) readahead.  It’s running the Cento= +s 4.1 distro, which uses a Linux 2.6.9 kernel.<BR> +<BR> +Same test as above, but with 17GB of data takes 69.7 seconds to scan (!) &n= +bsp;That’s 244.2MB/s, which is obviously double my earlier point of 11= +0-120MB/s.  This system is running with a 16MB Linux readahead setting,= + let’s try it with the default (I think) setting of 256KB – AHA!= + Now we get 171.4 seconds or 99.3MB/s.<BR> +<BR> +So, using the tuned setting of “blockdev —setra 16384” we= + get $6,000 / 244MB/s =3D 24.6 $/MB/s<BR> +If we use the default Linux setting it’s 2.5x worse.<BR> +<BR> +Raw data:<BR> +</FONT><FONT FACE=3D"Courier New">[llonergan@modena2 IVP]$ cat scan.sh <BR> +#!/bin/bash<BR> +<BR> +time psql -c "select count(*) from ivp.bigtable1" dgtestdb<BR> +[llonergan@modena2 IVP]$ cat sysout3<BR> +  count   <BR> +----------<BR> + 80000000<BR> +(1 row)<BR> +<BR> +<BR> +real    1m9.875s<BR> +user    0m0.000s<BR> +sys     0m0.004s<BR> +[llonergan@modena2 IVP]$ !du<BR> +du -sk dgtestdb/base<BR> +17021260        dgtestdb/base<BR> +</FONT></SPAN></BLOCKQUOTE><SPAN STYLE=3D'font-size:14.0px'><FONT FACE=3D"Couri= +er New"><BR> +</FONT><FONT FACE=3D"Verdana, Helvetica, Arial">Summary:<BR> +<BR> +<cough, cough> OK – you can get more I/O bandwidth out of the c= +urrent I/O path for sequential scan if you tune the filesystem for large rea= +dahead.  This is a cheap alternative to overhauling the executor to use= + asynch I/O.<BR> +<BR> +Still, there is a CPU limit here – this is not I/O bound, it is CPU l= +imited as evidenced by the sensitivity to readahead settings.   If= + the filesystem could do 1GB/s, you wouldn’t go any faster than 244MB/= +s.<BR> +<BR> +- Luke</FONT></SPAN> +</BODY> +</HTML> + + +--B_3215142822_2162763-- + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 15:45:19 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6BC05DB835 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 11:25:48 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 39852-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 15:25:51 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from net2.micro-automation.com (net2.micro-automation.com + [64.7.141.29]) + by svr1.postgresql.org (Postfix) with SMTP id 42E45DBAAE + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 11:25:44 -0400 (AST) +Received: (qmail 16600 invoked from network); 18 Nov 2005 15:25:49 -0000 +Received: from dcdsl.ebox.com (HELO ?192.168.1.2?) (davec@64.7.143.116) + by net2.micro-automation.com with SMTP; 18 Nov 2005 15:25:49 -0000 +In-Reply-To: <BFA32FA6.14027%llonergan@greenplum.com> +References: <BFA32FA6.14027%llonergan@greenplum.com> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: multipart/alternative; boundary=Apple-Mail-55--598469618 +Message-Id: <A4D5EB2A-73BC-43F8-8B5A-36268193A047@fastcrypt.com> +Cc: "Greg Stark" <gsstark@mit.edu>, "Joshua Marsh" <icub3d@gmail.com>, + pgsql-performance@postgresql.org +From: Dave Cramer <pg@fastcrypt.com> +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Fri, 18 Nov 2005 10:25:52 -0500 +To: Luke Lonergan <llonergan@greenplum.com> +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.129 required=5 tests=[AWL=-0.128, + HTML_FONT_BIG=0.256, HTML_MESSAGE=0.001] +X-Spam-Score: 0.129 +X-Spam-Level: +X-Archive-Number: 200511/379 +X-Sequence-Number: 15636 + + +--Apple-Mail-55--598469618 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/plain; + charset=WINDOWS-1252; + delsp=yes; + format=flowed + +Luke, + +Interesting numbers. I'm a little concerned about the use of blockdev =20= + +=97setra 16384. If I understand this correctly it assumes that the =20 +table is contiguous on the disk does it not ? + + +Dave +On 18-Nov-05, at 10:13 AM, Luke Lonergan wrote: + +> Dave, +> +> On 11/18/05 5:00 AM, "Dave Cramer" <pg@fastcrypt.com> wrote: +> > +> > Now there's an interesting line drawn in the sand. I presume you =20 +> have +> > numbers to back this up ? +> > +> > This should draw some interesting posts. +> +> Part 2: The answer +> +> System A: +>> This system is running RedHat 3 Update 4, with a Fedora 2.6.10 =20 +>> Linux kernel. +>> +>> On a single table with 15 columns (the Bizgres IVP) at a size =20 +>> double memory (2.12GB), Postgres 8.0.3 with Bizgres enhancements =20 +>> takes 32 seconds to scan the table: that=92s 66 MB/s. Not the =20 +>> efficiency I=92d hope from the onboard SATA controller that I=92d =20 +>> like, I would have expected to get 85% of the 100MB/s raw read =20 +>> performance. +>> +>> So that=92s $1,200 / 66 MB/s (without adjusting for 2003 price =20 +>> versus now) =3D 18.2 $/MB/s +>> +>> Raw data: +>> [llonergan@kite4 IVP]$ cat scan.sh +>> #!/bin/bash +>> +>> time psql -c "select count(*) from ivp.bigtable1" dgtestdb +>> [llonergan@kite4 IVP]$ cat sysout1 +>> count +>> ---------- +>> 10000000 +>> (1 row) +>> +>> +>> real 0m32.565s +>> user 0m0.002s +>> sys 0m0.003s +>> +>> Size of the table data: +>> [llonergan@kite4 IVP]$ du -sk dgtestdb/base +>> 2121648 dgtestdb/base +>> +> System B: +>> This system is running an XFS filesystem, and has been tuned to =20 +>> use very large (16MB) readahead. It=92s running the Centos 4.1 =20 +>> distro, which uses a Linux 2.6.9 kernel. +>> +>> Same test as above, but with 17GB of data takes 69.7 seconds to =20 +>> scan (!) That=92s 244.2MB/s, which is obviously double my earlier =20= + +>> point of 110-120MB/s. This system is running with a 16MB Linux =20 +>> readahead setting, let=92s try it with the default (I think) setting =20= + +>> of 256KB =96 AHA! Now we get 171.4 seconds or 99.3MB/s. +>> +>> So, using the tuned setting of =93blockdev =97setra 16384=94 we get =20= + +>> $6,000 / 244MB/s =3D 24.6 $/MB/s +>> If we use the default Linux setting it=92s 2.5x worse. +>> +>> Raw data: +>> [llonergan@modena2 IVP]$ cat scan.sh +>> #!/bin/bash +>> +>> time psql -c "select count(*) from ivp.bigtable1" dgtestdb +>> [llonergan@modena2 IVP]$ cat sysout3 +>> count +>> ---------- +>> 80000000 +>> (1 row) +>> +>> +>> real 1m9.875s +>> user 0m0.000s +>> sys 0m0.004s +>> [llonergan@modena2 IVP]$ !du +>> du -sk dgtestdb/base +>> 17021260 dgtestdb/base +> +> Summary: +> +> <cough, cough> OK =96 you can get more I/O bandwidth out of the =20 +> current I/O path for sequential scan if you tune the filesystem for =20= + +> large readahead. This is a cheap alternative to overhauling the =20 +> executor to use asynch I/O. +> +> Still, there is a CPU limit here =96 this is not I/O bound, it is CPU =20= + +> limited as evidenced by the sensitivity to readahead settings. If =20= + +> the filesystem could do 1GB/s, you wouldn=92t go any faster than =20 +> 244MB/s. +> +> - Luke + + +--Apple-Mail-55--598469618 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/html; + charset=WINDOWS-1252 + +<HTML><BODY style=3D"word-wrap: break-word; -khtml-nbsp-mode: space; = +-khtml-line-break: after-white-space; ">Luke,<DIV><BR = +class=3D"khtml-block-placeholder"></DIV><DIV><SPAN = +class=3D"Apple-style-span"><FONT class=3D"Apple-style-span" = +face=3D"Verdana" size=3D"4"><SPAN class=3D"Apple-style-span" = +style=3D"font-size: 14px;">Interesting numbers. I'm a little concerned = +about the use of</SPAN></FONT>=A0<SPAN style=3D""><FONT = +class=3D"Apple-style-span" size=3D"4"><SPAN class=3D"Apple-style-span" = +style=3D"font-size: 14px;"><FONT class=3D"Apple-style-span" = +face=3D"Verdana">blockdev =97setra 16384. If I understand this correctly = +it assumes that the table is contiguous on the disk does it not = +?</FONT></SPAN></FONT></SPAN><FONT class=3D"Apple-style-span" = +size=3D"4"><SPAN class=3D"Apple-style-span" style=3D"font-size: = +14px;"></SPAN></FONT></SPAN></DIV><DIV><FONT class=3D"Apple-style-span" = +face=3D"Verdana" size=3D"4"><SPAN class=3D"Apple-style-span" = +style=3D"font-size: 14px;"><BR = +class=3D"khtml-block-placeholder"></SPAN></FONT></DIV><DIV><FONT = +class=3D"Apple-style-span" face=3D"Verdana" size=3D"4"><SPAN = +class=3D"Apple-style-span" style=3D"font-size: 14px;"><BR = +class=3D"khtml-block-placeholder"></SPAN></FONT></DIV><DIV><SPAN = +class=3D"Apple-style-span"><FONT class=3D"Apple-style-span" = +size=3D"4"><SPAN class=3D"Apple-style-span" style=3D"font-size: = +14px;"><FONT class=3D"Apple-style-span" = +face=3D"Verdana">Dave<BR></FONT></SPAN></FONT><DIV><DIV>On 18-Nov-05, at = +10:13 AM, Luke Lonergan wrote:</DIV><BR = +class=3D"Apple-interchange-newline"><BLOCKQUOTE type=3D"cite"> <FONT = +face=3D"Verdana, Helvetica, Arial"><SPAN = +style=3D"font-size:14.0px">Dave,<BR> <BR> On 11/18/05 5:00 AM, "Dave = +Cramer" <<A href=3D"mailto:pg@fastcrypt.com">pg@fastcrypt.com</A>> = +wrote:<BR> <FONT color=3D"#0000FF">> <BR> > Now there's an = +interesting line drawn in the sand. I presume you have <BR> > numbers = +to back this up ?<BR> > <BR> > This should draw some interesting = +posts.<BR> </FONT><BR> Part 2: The answer<BR> <BR> System A:<BR> = +</SPAN></FONT><BLOCKQUOTE type=3D"cite"><FONT face=3D"Verdana, = +Helvetica, Arial"><SPAN style=3D"font-size:14.0px">This system is = +running RedHat 3 Update 4, with a Fedora 2.6.10 Linux kernel.<BR> <BR> = +On a single table with 15 columns (the Bizgres IVP) at a size double = +memory (2.12GB), Postgres 8.0.3 with Bizgres enhancements takes 32 = +seconds to scan the table: that=92s 66 MB/s. =A0Not the efficiency I=92d = +hope from the onboard SATA controller that I=92d like, I would have = +expected to get 85% of the 100MB/s raw read performance.<BR> <BR> So = +that=92s $1,200 / 66 MB/s (without adjusting for 2003 price versus now) = +=3D 18.2 $/MB/s<BR> <BR> Raw data:<BR> </SPAN></FONT><SPAN = +style=3D"font-size:14.0px"><FONT face=3D"Courier New">[llonergan@kite4 = +IVP]$ cat scan.sh <BR> #!/bin/bash<BR> <BR> time psql -c "select = +count(*) from ivp.bigtable1" dgtestdb<BR> [llonergan@kite4 IVP]$ cat = +sysout1<BR> =A0=A0count =A0=A0<BR> ----------<BR> =A010000000<BR> (1 = +row)<BR> <BR> <BR> real =A0=A0=A00m32.565s<BR> user =A0=A0=A00m0.002s<BR> = +sys =A0=A0=A0=A00m0.003s<BR> <BR> Size of the table data:<BR> = +[llonergan@kite4 IVP]$ du -sk dgtestdb/base<BR> 2121648 = +dgtestdb/base<BR> </FONT><FONT face=3D"Verdana, Helvetica, Arial"><BR> = +</FONT></SPAN></BLOCKQUOTE><SPAN style=3D"font-size:14.0px"><FONT = +face=3D"Verdana, Helvetica, Arial">System B:<BR> = +</FONT></SPAN><BLOCKQUOTE type=3D"cite"><SPAN = +style=3D"font-size:14.0px"><FONT face=3D"Verdana, Helvetica, Arial">This = +system is running an XFS filesystem, and has been tuned to use very = +large (16MB) readahead. =A0It=92s running the Centos 4.1 distro, which = +uses a Linux 2.6.9 kernel.<BR> <BR> Same test as above, but with 17GB of = +data takes 69.7 seconds to scan (!) =A0That=92s 244.2MB/s, which is = +obviously double my earlier point of 110-120MB/s. =A0This system is = +running with a 16MB Linux readahead setting, let=92s try it with the = +default (I think) setting of 256KB =96 AHA! Now we get 171.4 seconds or = +99.3MB/s.<BR> <BR> So, using the tuned setting of =93blockdev =97setra = +16384=94 we get $6,000 / 244MB/s =3D 24.6 $/MB/s<BR> If we use the = +default Linux setting it=92s 2.5x worse.<BR> <BR> Raw data:<BR> = +</FONT><FONT face=3D"Courier New">[llonergan@modena2 IVP]$ cat scan.sh = +<BR> #!/bin/bash<BR> <BR> time psql -c "select count(*) from = +ivp.bigtable1" dgtestdb<BR> [llonergan@modena2 IVP]$ cat sysout3<BR> = +=A0=A0count =A0=A0<BR> ----------<BR> =A080000000<BR> (1 row)<BR> <BR> = +<BR> real =A0=A0=A01m9.875s<BR> user =A0=A0=A00m0.000s<BR> sys = +=A0=A0=A0=A00m0.004s<BR> [llonergan@modena2 IVP]$ !du<BR> du -sk = +dgtestdb/base<BR> 17021260 =A0=A0=A0=A0=A0=A0=A0dgtestdb/base<BR> = +</FONT></SPAN></BLOCKQUOTE><SPAN style=3D"font-size:14.0px"><FONT = +face=3D"Courier New"><BR> </FONT><FONT face=3D"Verdana, Helvetica, = +Arial">Summary:<BR> <BR> <cough, cough> OK =96 you can get more = +I/O bandwidth out of the current I/O path for sequential scan if you = +tune the filesystem for large readahead. =A0This is a cheap alternative = +to overhauling the executor to use asynch I/O.<BR> <BR> Still, there is = +a CPU limit here =96 this is not I/O bound, it is CPU limited as = +evidenced by the sensitivity to readahead settings. =A0=A0If the = +filesystem could do 1GB/s, you wouldn=92t go any faster than = +244MB/s.<BR> <BR> - Luke</FONT></SPAN> = +</BLOCKQUOTE></DIV><BR></SPAN></DIV></BODY></HTML>= + +--Apple-Mail-55--598469618-- + +From pgsql-performance-owner@postgresql.org Fri Nov 18 15:43:53 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 25616DBAAE + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 11:27:57 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 39796-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 15:28:00 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw02.mi8.com [63.240.6.46]) + by svr1.postgresql.org (Postfix) with ESMTP id 6120CDBA92 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 11:27:52 -0400 (AST) +Received: from 172.16.1.112 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D2)); Fri, 18 Nov 2005 10:27:45 -0500 +X-Server-Uuid: 7829E76E-BB9E-4995-8473-3C0929DF7DD1 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 10:27:43 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 10:27:42 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 07:27:42 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: stange@rentec.com +cc: "Dave Cramer" <pg@fastcrypt.com>, "Greg Stark" <gsstark@mit.edu>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-ID: <BFA332EE.14035%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsTw0c95ObdkQGQ1Cr04ElJkGvZwABZDAP +In-Reply-To: <437DE960.9070606@rentec.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 18 Nov 2005 15:27:43.0217 (UTC) + FILETIME=[9E991E10:01C5EC54] +X-WSS-ID: 6F632D642RS9471348-06-01 +Content-Type: multipart/alternative; + boundary=B_3215143662_2194465 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[AWL=-0.000, + HTML_MESSAGE=0.001, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/378 +X-Sequence-Number: 15635 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3215143662_2194465 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Alan, + +On 11/18/05 6:46 AM, "Alan Stange" <stange@rentec.com> wrote: + +> That's 3 hours under load, with 80 compute clients beating on the +> database at the same time. We have the stats turned way up, so the +> analyze tends to read a big chunk of the tables a second time as +> well. We typically don't have three hours a day of idle time. + +So I guess you=B9re saying you don=B9t know what your I/O rate is? + +- Luke + + +--B_3215143662_2194465 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +<HTML> +<HEAD> +<TITLE>Re: [PERFORM] Hardware/OS recommendations for large databases (</TIT= +LE> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Alan,= +<BR> +<BR> +On 11/18/05 6:46 AM, "Alan Stange" <stange@rentec.com> wrot= +e:<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>That's 3 hours under load, with 80 compute clients beat= +ing on the<BR> +database at the same time.   We have the stats turned way up, so = +the<BR> +analyze tends to read a big chunk of the tables a second time as<BR> +well.    We typically don't have three hours a day of idle t= +ime.<BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'><BR> +So I guess you’re saying you don’t know what your I/O rate is?<= +BR> +<BR> +- Luke<BR> +</SPAN></FONT> +</BODY> +</HTML> + + +--B_3215143662_2194465-- + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 15:43:51 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id BDC99DBA92 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 11:30:52 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 40592-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 15:30:56 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id F04DADBAAF + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 11:30:49 -0400 (AST) +Received: from 172.16.1.110 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Fri, 18 Nov 2005 10:30:40 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 10:30:32 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 10:30:31 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 07:30:31 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Dave Cramer" <pg@fastcrypt.com> +cc: "Greg Stark" <gsstark@mit.edu>, "Joshua Marsh" <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Message-ID: <BFA33397.1403A%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsVGDnQ6yoPa0qRCyzZpo4/hApJQAAKGyl +In-Reply-To: <A4D5EB2A-73BC-43F8-8B5A-36268193A047@fastcrypt.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 18 Nov 2005 15:30:32.0129 (UTC) + FILETIME=[03470B10:01C5EC55] +X-WSS-ID: 6F632C1131S14498826-01-01 +Content-Type: multipart/alternative; + boundary=B_3215143831_2195651 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[AWL=-0.000, + HTML_MESSAGE=0.001, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/377 +X-Sequence-Number: 15634 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3215143831_2195651 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Dave, + +On 11/18/05 7:25 AM, "Dave Cramer" <pg@fastcrypt.com> wrote: + +> Luke, +>=20 +> Interesting numbers. I'm a little concerned about the use of=A0blockdev =8Bse= +tra +> 16384. If I understand this correctly it assumes that the table is contig= +uous +> on the disk does it not ? + +For optimum performance, yes it does. Remember that the poster is asking +about a 5TB warehouse. Decision support applications deal with large table= +s +and sequential scans a lot, and the data is generally contiguous on disk. +If delete gaps are there, they will generally vacuum them away. + +- Luke + +--B_3215143831_2195651 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +<HTML> +<HEAD> +<TITLE>Re: [PERFORM] Hardware/OS recommendations for large databases (</TIT= +LE> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Dave,= +<BR> +<BR> +On 11/18/05 7:25 AM, "Dave Cramer" <pg@fastcrypt.com> wrote= +:<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>Luke,<BR> +<BR> +Interesting numbers. I'm a little concerned about the use of=A0blockdev ̵= +2;setra 16384. If I understand this correctly it assumes that the table is c= +ontiguous on the disk does it not ?<BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'><BR> +For optimum performance, yes it does.  Remember that the poster is ask= +ing about a 5TB warehouse.  Decision support applications deal with lar= +ge tables and sequential scans a lot, and the data is generally contiguous o= +n disk.  If delete gaps are there, they will generally vacuum them away= +.<BR> +<BR> +- Luke</SPAN></FONT> +</BODY> +</HTML> + + +--B_3215143831_2195651-- + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 12:15:29 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CE4F4DBAAE + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 11:55:35 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 52034-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 15:55:39 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from bfccomputing.com (bfccomputing.com [217.160.248.65]) + by svr1.postgresql.org (Postfix) with ESMTP id 08A07D82C0 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 11:55:32 -0400 (AST) +Received: from [10.0.0.202] (68-169-200-61.sbtnvt.adelphia.net + [68.169.200.61]) + by bfccomputing.com (Postfix) with ESMTP + id 8E83BE8608; Fri, 18 Nov 2005 10:55:20 -0500 (EST) +In-Reply-To: <0F3B99E2-4575-42B8-8AAC-3FE4B231348C@fastcrypt.com> +References: <BFA2AFBA.13FC4%llonergan@greenplum.com> + <0F3B99E2-4575-42B8-8AAC-3FE4B231348C@fastcrypt.com> +Mime-Version: 1.0 (Apple Message framework v623) +Content-Type: text/plain; charset=US-ASCII; format=flowed +Message-Id: <d555b0eedb008ce34e18463cceb73b04@bfccomputing.com> +Content-Transfer-Encoding: 7bit +Cc: pgsql-performance@postgresql.org +From: Bill McGonigle <bill@bfccomputing.com> +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Fri, 18 Nov 2005 10:55:19 -0500 +To: Dave Cramer <pg@fastcrypt.com> +X-Mailer: Apple Mail (2.623) +X-bfccomputing-MailScanner-Information: Please contact the ISP for more + information +X-bfccomputing-MailScanner: Found to be clean +X-bfccomputing-MailScanner-SpamCheck: +X-MailScanner-From: bill@bfccomputing.com +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/357 +X-Sequence-Number: 15614 + +On Nov 18, 2005, at 08:00, Dave Cramer wrote: + +>> A $1,000 system with one CPU and two SATA disks in a software RAID0 +>> will +>> perform exactly the same as a $80,000 system with 8 dual core CPUs +>> and the +>> world's best SCSI RAID hardware on a large database for decision +>> support +>> (what the poster asked about). +> +> Now there's an interesting line drawn in the sand. I presume you have +> numbers to back this up ? +> This should draw some interesting posts. + +There is some truth to it. For an app I'm currently running (full-text +search using tsearch2 on ~100MB of data) on: + +Dev System: +Asus bare-bones bookshelf case/mobo +3GHz P4 w/ HT +800MHz memory Bus +Fedora Core 3 (nightly update) +1GB RAM +1 SATA Seagate disk (7200RPM, 8MB Cache) +$800 +worst-case query: 7.2 seconds + +now, the machine I'm deploying to: + +Dell SomthingOrOther +(4) 2.4GHz Xeons +533MHz memory bus +RedHat Enterprise 3.6 +1GB RAM +(5) 150000 RPM Ultra SCSI 320 on an Adaptec RAID 5 controller + > $10000 +same worst-case query: 9.6 seconds + +Now it's not apples-to-apples. There's a kernel 2.4 vs. 2.6 difference +and the memory bus is much faster and I'm not sure what kind of context +switching hit you get with the Xeon MP memory controller. On a +previous postgresql app I did I ran nearly identically spec'ed machines +except for the memory bus and saw about a 30% boost in performance just +with the 800MHz bus. I imagine the Opteron bus does even better. + +So the small machine is probably slower on disk but makes up for it in +single-threaded access to CPU and memory speed. But if this app were to +be scaled it would make much more sense to cluster several $800 +machines than it would to buy 'big-iron'. + +-Bill +----- +Bill McGonigle, Owner Work: 603.448.4440 +BFC Computing, LLC Home: 603.448.1668 +bill@bfccomputing.com Mobile: 603.252.2606 +http://www.bfccomputing.com/ Pager: 603.442.1833 +Jabber: flowerpt@gmail.com Text: bill+text@bfccomputing.com +Blog: http://blog.bfccomputing.com/ + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 12:12:33 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 81B1CDBA5F + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 12:05:20 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 53903-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 16:05:18 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from yertle.kcilink.com (yertle.kcilink.com [65.205.34.180]) + by svr1.postgresql.org (Postfix) with ESMTP id D0925DB77A + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 12:05:17 -0400 (AST) +Received: from [192.168.7.103] (host-103.int.kcilink.com [192.168.7.103]) + by yertle.kcilink.com (Postfix) with ESMTP id 51F42B814 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 11:05:17 -0500 (EST) +Mime-Version: 1.0 (Apple Message framework v746.2) +In-Reply-To: <BFA2AFBA.13FC4%llonergan@greenplum.com> +References: <BFA2AFBA.13FC4%llonergan@greenplum.com> +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: <7F33229E-AE95-436B-AB2F-01AC023DD7EE@khera.org> +Content-Transfer-Encoding: 7bit +From: Vivek Khera <vivek@khera.org> +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Fri, 18 Nov 2005 11:05:16 -0500 +To: Postgresql Performance <pgsql-performance@postgresql.org> +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/356 +X-Sequence-Number: 15613 + +On Nov 18, 2005, at 1:07 AM, Luke Lonergan wrote: + +> A $1,000 system with one CPU and two SATA disks in a software RAID0 +> will +> perform exactly the same as a $80,000 system with 8 dual core CPUs +> and the +> world's best SCSI RAID hardware on a large database for decision +> support +> (what the poster asked about). + +Hahahahahahahahahahahahaha! Whooo... needed to fall out of my chair +laughing this morning. + +I can tell you from direct personal experience that you're just plain +wrong. + +I've had to move my primary DB server from a dual P3 1GHz with 4-disk +RAID10 SCSI, to Dual P3 2GHz with 14-disk RAID10 and faster drives, +to Dual Opteron 2GHz with 8-disk RAID10 and even faster disks to keep +up with my load on a 60+ GB database. The Dual opteron system has +just a little bit of extra capacity if I offload some of the +reporting operations to a replicated copy (via slony1). If I run all +the queries on the one DB it can't keep up. + +One most telling point about the difference in speed is that the 14- +disk array system cannot keep up with the replication being generated +by the dual opteron, even when it is no doing any other queries of +its own. The I/O system just ain't fast enough. + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 12:09:53 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 83D09D6D50 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 12:07:08 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 47817-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 16:07:06 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from yertle.kcilink.com (yertle.kcilink.com [65.205.34.180]) + by svr1.postgresql.org (Postfix) with ESMTP id 0DD23DBAB3 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 12:07:06 -0400 (AST) +Received: from [192.168.7.103] (host-103.int.kcilink.com [192.168.7.103]) + by yertle.kcilink.com (Postfix) with ESMTP id 70E82B80A + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 11:07:05 -0500 (EST) +Mime-Version: 1.0 (Apple Message framework v746.2) +In-Reply-To: <BFA32FA6.14027%llonergan@greenplum.com> +References: <BFA32FA6.14027%llonergan@greenplum.com> +Content-Type: multipart/alternative; boundary=Apple-Mail-1--595997702 +Message-Id: <1F5BD2B1-8A75-498E-ADB7-8CB661066013@khera.org> +From: Vivek Khera <vivek@khera.org> +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Fri, 18 Nov 2005 11:07:04 -0500 +To: Postgresql Performance <pgsql-performance@postgresql.org> +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[AWL=-0.000, + HTML_MESSAGE=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/355 +X-Sequence-Number: 15612 + + +--Apple-Mail-1--595997702 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/plain; + charset=WINDOWS-1252; + delsp=yes; + format=flowed + + +On Nov 18, 2005, at 10:13 AM, Luke Lonergan wrote: + +> Still, there is a CPU limit here =96 this is not I/O bound, it is CPU =20= + +> limited as evidenced by the sensitivity to readahead settings. If =20= + +> the filesystem could do 1GB/s, you wouldn=92t go any faster than =20 +> 244MB/s. + +Yeah, and mysql would probably be faster on your trivial queries. =20 +Try concurrent large joins and updates and see which system is faster. + + +--Apple-Mail-1--595997702 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/html; + charset=WINDOWS-1252 + +<HTML><BODY style=3D"word-wrap: break-word; -khtml-nbsp-mode: space; = +-khtml-line-break: after-white-space; "><BR><DIV><DIV>On Nov 18, 2005, = +at 10:13 AM, Luke Lonergan wrote:</DIV><BR = +class=3D"Apple-interchange-newline"><BLOCKQUOTE type=3D"cite"><SPAN = +class=3D"Apple-style-span" style=3D"border-collapse: separate; = +border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Georgia; = +font-size: 14px; font-style: normal; font-variant: normal; font-weight: = +normal; letter-spacing: normal; line-height: normal; text-align: auto; = +-khtml-text-decorations-in-effect: none; text-indent: 0px; = +-apple-text-size-adjust: auto; text-transform: none; orphans: 2; = +white-space: normal; widows: 2; word-spacing: 0px; "><SPAN = +style=3D"font-size:14.0px"><FONT face=3D"Verdana, Helvetica, = +Arial"><SPAN class=3D"Apple-style-span" style=3D"font-family: Verdana; = +">Still, there is a CPU limit here =96 this is not I/O bound, it is CPU = +limited as evidenced by the sensitivity to readahead settings. =A0=A0If = +the filesystem could do 1GB/s, you wouldn=92t go any faster than = +244MB/s.</SPAN><BR style=3D"font-family: Verdana; = +"></FONT></SPAN></SPAN></BLOCKQUOTE></DIV><BR><DIV>Yeah, and mysql would = +probably be faster on your trivial queries.=A0 Try concurrent large = +joins and updates and see which system is faster.</DIV><DIV><BR = +class=3D"khtml-block-placeholder"></DIV></BODY></HTML>= + +--Apple-Mail-1--595997702-- + +From pgsql-performance-owner@postgresql.org Fri Nov 18 15:43:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9B5A1DB77A + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 12:13:18 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 54914-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 16:13:16 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtp104.rog.mail.re2.yahoo.com (smtp104.rog.mail.re2.yahoo.com + [206.190.36.82]) + by svr1.postgresql.org (Postfix) with SMTP id 9C4A4DBAAE + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 12:13:14 -0400 (AST) +Received: (qmail 29651 invoked from network); 18 Nov 2005 16:13:14 -0000 +Received: from unknown (HELO phlogiston.dydns.org) + (a.sullivan@rogers.com@209.222.54.227 with login) + by smtp104.rog.mail.re2.yahoo.com with SMTP; 18 Nov 2005 16:13:14 -0000 +Received: by phlogiston.dydns.org (Postfix, from userid 1000) + id B888740B5; Fri, 18 Nov 2005 11:13:12 -0500 (EST) +Date: Fri, 18 Nov 2005 11:13:12 -0500 +From: Andrew Sullivan <ajs@crankycanuck.ca> +To: Guillaume Smet <guillaume.smet@openwide.fr> +Cc: Andrew Sullivan <ajs@crankycanuck.ca>, + pgsql-performance@postgresql.org +Subject: Re: weird performances problem +Message-ID: <20051118161312.GC28967@phlogiston.dyndns.org> +References: <437CC21D.8070402@openwide.fr> + <20051117221314.GC26696@phlogiston.dyndns.org> + <437D13AA.4010309@openwide.fr> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <437D13AA.4010309@openwide.fr> +User-Agent: Mutt/1.5.9i +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/376 +X-Sequence-Number: 15633 + +On Fri, Nov 18, 2005 at 12:35:06AM +0100, Guillaume Smet wrote: +> sort_mem = 32768 + +I would be very suspicious of that much memory for sort. Please see +the docs for what that does. That is the amount that _each sort_ can +allocate before spilling to disk. If some set of your users are +causing complicated queries with, say, four sorts apiece, then each +user is potentially allocating 4x that much memory. That's going to +wreak havoc on your disk buffers (which are tricky to monitor on most +systems, and impossible on some). + +This'd be the first knob I'd twiddle, for sure. + +A + +-- +Andrew Sullivan | ajs@crankycanuck.ca +It is above all style through which power defers to reason. + --J. Robert Oppenheimer + +From pgsql-performance-owner@postgresql.org Fri Nov 18 15:43:38 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 984ABDBAB1 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 12:14:33 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 54005-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 16:14:31 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id D644DDBAAE + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 12:14:29 -0400 (AST) +Received: from ram.rentec.com (mailhost [192.5.35.66]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jAIGDeP9024547 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Fri, 18 Nov 2005 11:13:41 -0500 (EST) +X-Source: non-mednet +Received: from [172.26.132.145] (hoopoe.rentec.com [172.26.132.145]) + by ram.rentec.com (8.13.1/8.12.1) with ESMTP id jAIGD9qD006841; + Fri, 18 Nov 2005 11:13:09 -0500 (EST) +Message-ID: <437DFDB8.1030208@rentec.com> +Date: Fri, 18 Nov 2005 11:13:44 -0500 +From: Alan Stange <stange@rentec.com> +Reply-To: stange@rentec.com +Organization: Renaissance Technologies Corp. +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Luke Lonergan <llonergan@greenplum.com> +CC: Dave Cramer <pg@fastcrypt.com>, Greg Stark <gsstark@mit.edu>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA332EE.14035%llonergan@greenplum.com> +In-Reply-To: <BFA332EE.14035%llonergan@greenplum.com> +Content-Type: text/plain; charset=windows-1252; format=flowed +Content-Transfer-Encoding: 8bit +X-Logged: Logged by unicorn.rentec.com as jAIGDeP9024547 at Fri Nov 18 + 11:13:41 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.019 required=5 tests=[AWL=0.019] +X-Spam-Score: 0.019 +X-Spam-Level: +X-Archive-Number: 200511/375 +X-Sequence-Number: 15632 + +Luke Lonergan wrote: +> Alan, +> +> On 11/18/05 6:46 AM, "Alan Stange" <stange@rentec.com> wrote: +> +> That's 3 hours under load, with 80 compute clients beating on the +> database at the same time. We have the stats turned way up, so the +> analyze tends to read a big chunk of the tables a second time as +> well. We typically don't have three hours a day of idle time. +> +> +> So I guess you�re saying you don�t know what your I/O rate is? +No, I'm say *you* don't know what my IO rate is. + +I told you in my initial post that I was observing numbers in excess of +what you claiming, but you seemed to think I didn't know how to measure +an IO rate. + +I should note too that our system uses about 20% of a single cpu when +performing a table scan at >100MB/s of IO. I think you claimed the +system would be cpu bound at this low IO rate. + +Cheers, + +-- Alan + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 15:43:17 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D9562D82C0 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 12:16:57 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 53168-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 16:16:55 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw02.mi8.com [63.240.6.46]) + by svr1.postgresql.org (Postfix) with ESMTP id BC3D8DBAC0 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 12:16:53 -0400 (AST) +Received: from 172.16.1.110 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D2)); Fri, 18 Nov 2005 11:16:47 -0500 +X-Server-Uuid: 7829E76E-BB9E-4995-8473-3C0929DF7DD1 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 11:16:40 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 11:16:40 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 08:16:39 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Vivek Khera" <vivek@khera.org>, + "Postgresql Performance" <pgsql-performance@postgresql.org> +Message-ID: <BFA33E67.1404D%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsWvFEknbFGdXQQ46m0ym7HfvpqgAAIMyI +In-Reply-To: <1F5BD2B1-8A75-498E-ADB7-8CB661066013@khera.org> +MIME-Version: 1.0 +X-OriginalArrivalTime: 18 Nov 2005 16:16:40.0865 (UTC) + FILETIME=[7592A110:01C5EC5B] +X-WSS-ID: 6F6321E52RS9512144-08-01 +Content-Type: multipart/alternative; + boundary=B_3215146600_2400117 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[AWL=-0.000, + HTML_MESSAGE=0.001, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/374 +X-Sequence-Number: 15631 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3215146600_2400117 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Vivek, + +On 11/18/05 8:07 AM, "Vivek Khera" <vivek@khera.org> wrote: + +>=20 +> On Nov 18, 2005, at 10:13 AM, Luke Lonergan wrote: +>=20 +>> Still, there is a CPU limit here =AD this is not I/O bound, it is CPU limi= +ted +>> as evidenced by the sensitivity to readahead settings. =A0=A0If the filesyst= +em +>> could do 1GB/s, you wouldn=B9t go any faster than 244MB/s. +>=20 +> Yeah, and mysql would probably be faster on your trivial queries.=A0 Try +> concurrent large joins and updates and see which system is faster. + +That=B9s what we do to make a living. And it=B9s Oracle that a lot faster +because they implemented a much tighter, optimized I/O path to disk than +Postgres. + +Since you asked, we bought the 5 systems as a cluster =AD and with Bizgres MP= +P +we get close to 400MB/s per machine on complex queries. + +- Luke + +--B_3215146600_2400117 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +<HTML> +<HEAD> +<TITLE>Re: [PERFORM] Hardware/OS recommendations for large databases (</TIT= +LE> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Vivek= +,<BR> +<BR> +On 11/18/05 8:07 AM, "Vivek Khera" <vivek@khera.org> wrote:= +<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'><BR> +On Nov 18, 2005, at 10:13 AM, Luke Lonergan wrote:<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>Still, there is a CPU limit here – this is not I/= +O bound, it is CPU limited as evidenced by the sensitivity to readahead sett= +ings. =A0=A0If the filesystem could do 1GB/s, you wouldn’t go any faster t= +han 244MB/s.<BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'><BR> +Yeah, and mysql would probably be faster on your trivial queries.=A0 Try conc= +urrent large joins and updates and see which system is faster.<BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'><BR> +That’s what we do to make a living.  And it’s Oracle that = +a <B>lot</B> faster because they implemented a much tighter, optimized I/O p= +ath to disk than Postgres.<BR> +<BR> +Since you asked, we bought the 5 systems as a cluster – and with Bizg= +res MPP we get close to 400MB/s per machine on complex queries.<BR> +<BR> +- Luke  </SPAN></FONT> +</BODY> +</HTML> + + +--B_3215146600_2400117-- + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 15:43:14 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 94778DBAAD + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 12:18:21 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 54874-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 16:18:19 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw01.mi8.com [63.240.6.47]) + by svr1.postgresql.org (Postfix) with ESMTP id A5C1EDBAB3 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 12:18:18 -0400 (AST) +Received: from 172.16.1.110 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D1)); Fri, 18 Nov 2005 11:17:54 -0500 +X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 11:17:49 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 11:17:48 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 08:17:48 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: stange@rentec.com +cc: "Dave Cramer" <pg@fastcrypt.com>, "Greg Stark" <gsstark@mit.edu>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-ID: <BFA33EAC.1404E%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsWynYmaQcVW8AQ/6P36vjrmRtnwAAHO+A +In-Reply-To: <437DFDB8.1030208@rentec.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 18 Nov 2005 16:17:49.0336 (UTC) + FILETIME=[9E627980:01C5EC5B] +X-WSS-ID: 6F6321F621G13526393-04-01 +Content-Type: multipart/alternative; + boundary=B_3215146668_2362154 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[AWL=-0.000, + HTML_MESSAGE=0.001, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/373 +X-Sequence-Number: 15630 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3215146668_2362154 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit + +Alan, + +On 11/18/05 8:13 AM, "Alan Stange" <stange@rentec.com> wrote: + +> I told you in my initial post that I was observing numbers in excess of +> what you claiming, but you seemed to think I didn't know how to measure +> an IO rate. +> +Prove me wrong, post your data. + +> I should note too that our system uses about 20% of a single cpu when +> performing a table scan at >100MB/s of IO. I think you claimed the +> system would be cpu bound at this low IO rate. + +See above. + +- Luke +> + + + +--B_3215146668_2362154 +Content-Type: text/html; + charset=us-ascii +Content-Transfer-Encoding: quoted-printable + +<HTML> +<HEAD> +<TITLE>Re: [PERFORM] Hardware/OS recommendations for large databases (</TIT= +LE> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Alan,= +<BR> +<BR> +On 11/18/05 8:13 AM, "Alan Stange" <stange@rentec.com> wrot= +e:<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>I told you in my initial post that I was observing numb= +ers in excess of<BR> +what you claiming, but you seemed to think I didn't know how to measure<BR> +an IO rate.<BR> +<BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'>Prove me wrong, post your data.<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>I should note too that our system uses about 20% of a s= +ingle cpu when<BR> +performing a table scan at >100MB/s of IO. I think you claimed the<BR> +system would be cpu bound at this low IO rate.<BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'><BR> +See above.<BR> +<BR> +- Luke<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'><BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'><BR> +</SPAN></FONT> +</BODY> +</HTML> + + +--B_3215146668_2362154-- + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 15:43:07 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B3014DBAB3 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 12:20:35 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 54529-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 16:20:33 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw01.mi8.com [63.240.6.47]) + by svr1.postgresql.org (Postfix) with ESMTP id 8A08AD82C0 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 12:20:32 -0400 (AST) +Received: from 172.16.1.112 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D1)); Fri, 18 Nov 2005 11:20:12 -0500 +X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 11:20:11 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 11:20:11 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 08:20:11 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Vivek Khera" <vivek@khera.org>, + "Postgresql Performance" <pgsql-performance@postgresql.org> +Message-ID: <BFA33F3B.1404F%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsWzbRV+j6Vby9QAyiN/Gwt8OJ2wAALwAZ +In-Reply-To: <7F33229E-AE95-436B-AB2F-01AC023DD7EE@khera.org> +MIME-Version: 1.0 +X-OriginalArrivalTime: 18 Nov 2005 16:20:11.0938 (UTC) + FILETIME=[F361D020:01C5EC5B] +X-WSS-ID: 6F6320B121G13528235-01-01 +Content-Type: multipart/alternative; + boundary=B_3215146811_2392297 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[AWL=-0.000, + HTML_MESSAGE=0.001, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/372 +X-Sequence-Number: 15629 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3215146811_2392297 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Vivek,=20 + +On 11/18/05 8:05 AM, "Vivek Khera" <vivek@khera.org> wrote: + +> I can tell you from direct personal experience that you're just plain +> wrong. +>=20 +> up with my load on a 60+ GB database. The Dual opteron system has + +I=B9m always surprised by what passes for a large database. The poster is +talking about 5,000GB, or almost 100 times the data you have. + +Post your I/O numbers on sequential scan. Sequential scan is critical for +Decision Support / Data Warehousing. + +- Luke + +--B_3215146811_2392297 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +<HTML> +<HEAD> +<TITLE>Re: [PERFORM] Hardware/OS recommendations for large databases (</TIT= +LE> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Vivek= +, <BR> +<BR> +On 11/18/05 8:05 AM, "Vivek Khera" <vivek@khera.org> wrote:= +<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>I can tell you from direct personal experience that you= +'re just plain <BR> +wrong.<BR> +<BR> +up with my load on a 60+ GB database.  The Dual opteron system has <BR= +> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'><BR> +I’m always surprised by what passes for a large database.  The p= +oster is talking about 5,000GB, or almost 100 times the data you have.<BR> +<BR> +Post your I/O numbers on sequential scan.  Sequential scan is critical= + for Decision Support / Data Warehousing.<BR> +<BR> +- Luke </SPAN></FONT> +</BODY> +</HTML> + + +--B_3215146811_2392297-- + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 14:21:30 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A7558DBABC + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 12:28:44 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 54554-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 16:28:42 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.199]) + by svr1.postgresql.org (Postfix) with ESMTP id 6CE6ADBAAE + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 12:28:41 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id i28so643224wra + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 08:28:41 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=OhND7JtrNA0UcN+mJjo9pHEZTUinRTqxMteAy8rao47DE1N5vi9tcwChWerARV7kEi0o6Tn3pEOnnyTDS5Y0sK0GrQKjAi8U8vs/UBbgtICCoDyCruFHtjWcEqPaukFpwvV+T+DDjTv0SwAjCMw1oUq7ZAEIbTrOiXRVnuU+L50= +Received: by 10.54.121.9 with SMTP id t9mr2396495wrc; + Fri, 18 Nov 2005 08:28:41 -0800 (PST) +Received: by 10.54.82.5 with HTTP; Fri, 18 Nov 2005 08:28:40 -0800 (PST) +Message-ID: <33c6269f0511180828m3bc7f41dp186b4573792bf6a0@mail.gmail.com> +Date: Fri, 18 Nov 2005 11:28:40 -0500 +From: Alex Turner <armtuk@gmail.com> +To: Luke Lonergan <llonergan@greenplum.com> +Subject: Re: Hardware/OS recommendations for large databases ( +Cc: Dave Cramer <pg@fastcrypt.com>, Greg Stark <gsstark@mit.edu>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +In-Reply-To: <BFA32FA6.14027%llonergan@greenplum.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=WINDOWS-1252 +Content-Transfer-Encoding: base64 +Content-Disposition: inline +References: <0F3B99E2-4575-42B8-8AAC-3FE4B231348C@fastcrypt.com> + <BFA32FA6.14027%llonergan@greenplum.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/364 +X-Sequence-Number: 15621 + +T2sgLSBzbyBJIHJhbiB0aGUgc2FtZSB0ZXN0IG9uIG15IHN5c3RlbSBhbmQgZ2V0IGEgdG90YWwg +c3BlZWQgb2YKMTEzTUIvc2VjLiAgV2h5IGlzIHRoaXM/ICBXaHkgaXMgdGhlIHN5c3RlbSBzbyBs +aW1pdGVkIHRvIGFyb3VuZCBqdXN0CjExME1CL3NlYz8gIEkgdHVuZWQgcmVhZCBhaGVhZCB1cCBh 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mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D1)); Fri, 18 Nov 2005 11:31:01 -0500 +X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 11:31:01 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 11:31:01 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 08:31:00 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Bill McGonigle" <bill@bfccomputing.com>, "Dave Cramer" <pg@fastcrypt.com> +cc: pgsql-performance@postgresql.org +Message-ID: <BFA341C4.14059%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsXA9ODu7eWyQrRSGPSXAUktgd9wAAWZZO +In-Reply-To: <d555b0eedb008ce34e18463cceb73b04@bfccomputing.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 18 Nov 2005 16:31:01.0848 (UTC) + FILETIME=[76C23580:01C5EC5D] +X-WSS-ID: 6F60DE4F21G13535249-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.253 required=5 tests=[AWL=0.000, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.253 +X-Spam-Level: * +X-Archive-Number: 200511/363 +X-Sequence-Number: 15620 + +Bill, + +On 11/18/05 7:55 AM, "Bill McGonigle" <bill@bfccomputing.com> wrote: +> +> There is some truth to it. For an app I'm currently running (full-text +> search using tsearch2 on ~100MB of data) on: + +Do you mean 100GB? Sounds like you are more like a decision support +/warehousing application. + +> Dev System: +> Asus bare-bones bookshelf case/mobo +> 3GHz P4 w/ HT +> 800MHz memory Bus +> Fedora Core 3 (nightly update) +> 1GB RAM +> 1 SATA Seagate disk (7200RPM, 8MB Cache) +> $800 +> worst-case query: 7.2 seconds + +About the same machine I posted results for, except I had two faster disks. + +> now, the machine I'm deploying to: +> +> Dell SomthingOrOther +> (4) 2.4GHz Xeons +> 533MHz memory bus +> RedHat Enterprise 3.6 +> 1GB RAM +> (5) 150000 RPM Ultra SCSI 320 on an Adaptec RAID 5 controller +>> $10000 +> same worst-case query: 9.6 seconds + +Your problem here is the HW RAID controller - if you dump it and use the +onboard SCSI channels and Linux RAID you will see a jump from 40MB/s to +about 220MB/s in read performance and from 20MB/s to 110MB/s write +performance. It will use less CPU too. + +> Now it's not apples-to-apples. There's a kernel 2.4 vs. 2.6 difference +> and the memory bus is much faster and I'm not sure what kind of context +> switching hit you get with the Xeon MP memory controller. On a +> previous postgresql app I did I ran nearly identically spec'ed machines +> except for the memory bus and saw about a 30% boost in performance just +> with the 800MHz bus. I imagine the Opteron bus does even better. + +Memory bandwidth is so high on both that it's not a factor. Context +switching / memory bus contention isn't either. + +> So the small machine is probably slower on disk but makes up for it in +> single-threaded access to CPU and memory speed. But if this app were to +> be scaled it would make much more sense to cluster several $800 +> machines than it would to buy 'big-iron'. + +Yes it does - by a lot too. Also, having a multiprocessing executor gets +all of each machine by having multiple CPUs scan simultaneously. + +- Luke + + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 14:04:17 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9FD13DBABC + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 12:33:59 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 55292-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 16:33:57 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw01.mi8.com [63.240.6.47]) + by svr1.postgresql.org (Postfix) with ESMTP id DCCE0DBAB1 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 12:33:56 -0400 (AST) +Received: from 172.16.1.110 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D1)); Fri, 18 Nov 2005 11:33:43 -0500 +X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 11:33:36 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 11:33:36 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 08:33:35 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Alex Turner" <armtuk@gmail.com> +cc: "Dave Cramer" <pg@fastcrypt.com>, "Greg Stark" <gsstark@mit.edu>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-ID: <BFA3425F.1405B%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsXdILENDsmFhREdqKawANk63kWA== +In-Reply-To: <33c6269f0511180828m3bc7f41dp186b4573792bf6a0@mail.gmail.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 18 Nov 2005 16:33:36.0640 (UTC) + FILETIME=[D3059800:01C5EC5D] +X-WSS-ID: 6F60DDC721G13536843-05-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.253 required=5 tests=[AWL=0.000, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.253 +X-Spam-Level: * +X-Archive-Number: 200511/362 +X-Sequence-Number: 15619 + +Alex, + +On 11/18/05 8:28 AM, "Alex Turner" <armtuk@gmail.com> wrote: + +> Ok - so I ran the same test on my system and get a total speed of +113MB/sec. +> Why is this? Why is the system so limited to around just +110MB/sec? I +> tuned read ahead up a bit, and my results improve a +bit.. + +OK! Now we're on the same page. Finally someone who actually tests! + +Check the CPU usage while it's doing the scan. Know what it's doing? +Memory copies. We've profiled it extensively. + +So - that's the suckage - throwing more CPU power helps a bit, but the +underlying issue is poorly optimized code in the Postgres executor and lack +of I/O asynchrony. + +- Luke + + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 13:35:52 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A78EDDBAB9 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 13:31:59 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 63310-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 17:31:58 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id F1906DBA9A + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 13:31:56 -0400 (AST) +Received: from ram.rentec.com (mailhost [192.5.35.66]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jAIHVTNL027900 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Fri, 18 Nov 2005 12:31:31 -0500 (EST) +X-Source: non-mednet +Received: from [172.26.132.145] (hoopoe.rentec.com [172.26.132.145]) + by ram.rentec.com (8.13.1/8.12.1) with ESMTP id jAIHUwrB012673; + Fri, 18 Nov 2005 12:30:58 -0500 (EST) +Message-ID: <437E0FF5.5090203@rentec.com> +Date: Fri, 18 Nov 2005 12:31:33 -0500 +From: Alan Stange <stange@rentec.com> +Reply-To: stange@rentec.com +Organization: Renaissance Technologies Corp. +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Luke Lonergan <llonergan@greenplum.com> +CC: Dave Cramer <pg@fastcrypt.com>, Greg Stark <gsstark@mit.edu>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA33EAC.1404E%llonergan@greenplum.com> +In-Reply-To: <BFA33EAC.1404E%llonergan@greenplum.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jAIHVTNL027900 at Fri Nov 18 + 12:31:31 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.027 required=5 tests=[AWL=0.027] +X-Spam-Score: 0.027 +X-Spam-Level: +X-Archive-Number: 200511/361 +X-Sequence-Number: 15618 + +Luke Lonergan wrote: +> Alan, +> +> On 11/18/05 8:13 AM, "Alan Stange" <stange@rentec.com> wrote: +> +> I told you in my initial post that I was observing numbers in +> excess of +> what you claiming, but you seemed to think I didn't know how to +> measure +> an IO rate. +> +> Prove me wrong, post your data. +> +> I should note too that our system uses about 20% of a single cpu when +> performing a table scan at >100MB/s of IO. I think you claimed the +> system would be cpu bound at this low IO rate. +> +> +> See above. +Here's the output from one iteration of iostat -k 60 while the box is +doing a select count(1) on a 238GB table. + +avg-cpu: %user %nice %sys %iowait %idle + 0.99 0.00 17.97 32.40 48.64 + +Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn +sdd 345.95 130732.53 0.00 7843952 0 + +We're reading 130MB/s for a full minute. About 20% of a single cpu was +being used. The remainder being idle. + +We've done nothing fancy and achieved results you claim shouldn't be +possible. This is a system that was re-installed yesterday, no tuning +was done to the file systems, kernel or storage array. + +What am I doing wrong? + +9 years ago I co-designed a petabyte data store with a goal of 1GB/s IO +(for a DOE lab). And now I don't know what I'm doing, + +Cheers, + +-- Alan + +From pgsql-performance-owner@postgresql.org Fri Nov 18 15:40:29 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 66E38DBAE9 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 13:54:24 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 66191-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 17:54:22 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw02.mi8.com [63.240.6.46]) + by svr1.postgresql.org (Postfix) with ESMTP id 25362DB7B4 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 13:54:20 -0400 (AST) +Received: from 172.16.1.110 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D2)); Fri, 18 Nov 2005 12:54:15 -0500 +X-Server-Uuid: 7829E76E-BB9E-4995-8473-3C0929DF7DD1 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 12:54:08 -0500 +Received: from 67.103.45.218 ([67.103.45.218]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.105]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 12:54:07 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 09:54:07 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: stange@rentec.com +cc: "Dave Cramer" <pg@fastcrypt.com>, "Greg Stark" <gsstark@mit.edu>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-ID: <BFA3553F.1406D%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsZfZw6TioWM8ESuOgRPEpH6gXiQAAxu1v +In-Reply-To: <437E0FF5.5090203@rentec.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 18 Nov 2005 17:54:08.0402 (UTC) + FILETIME=[12F9F720:01C5EC69] +X-WSS-ID: 6F60CACD2RS9590108-05-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[AWL=0.000, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/369 +X-Sequence-Number: 15626 + +Alan, + +On 11/18/05 9:31 AM, "Alan Stange" <stange@rentec.com> wrote: + +> Here's the output from one iteration of iostat -k 60 while the box is +> doing a select count(1) on a 238GB table. +> +> avg-cpu: %user %nice %sys %iowait %idle +> 0.99 0.00 17.97 32.40 48.64 +> +> Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn +> sdd 345.95 130732.53 0.00 7843952 0 +> +> We're reading 130MB/s for a full minute. About 20% of a single cpu was +> being used. The remainder being idle. + +Cool - thanks for the results. Is that % of one CPU, or of 2? Was the +system otherwise idle? + +> We've done nothing fancy and achieved results you claim shouldn't be +> possible. This is a system that was re-installed yesterday, no tuning +> was done to the file systems, kernel or storage array. + +Are you happy with 130MB/s? How much did you pay for that? Is it more than +$2,000, or double my 2003 PC? + +> What am I doing wrong? +> +> 9 years ago I co-designed a petabyte data store with a goal of 1GB/s IO +> (for a DOE lab). And now I don't know what I'm doing, + +Cool. Would that be Sandia? + +We routinely sustain 2,000 MB/s from disk on 16x 2003 era machines on +complex queries. + +- Luke + + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 14:41:12 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6A8BBD6D50 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 14:31:04 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 68737-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 18:31:03 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id E3E2BDBAB3 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 14:30:56 -0400 (AST) +Received: from ram.rentec.com (mailhost [192.5.35.66]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jAIIU1Qe000149 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Fri, 18 Nov 2005 13:30:02 -0500 (EST) +X-Source: non-mednet +Received: from [172.26.132.145] (hoopoe.rentec.com [172.26.132.145]) + by ram.rentec.com (8.13.1/8.12.1) with ESMTP id jAIITU9l017902; + Fri, 18 Nov 2005 13:29:30 -0500 (EST) +Message-ID: <437E1DAE.1070301@rentec.com> +Date: Fri, 18 Nov 2005 13:30:06 -0500 +From: Alan Stange <stange@rentec.com> +Reply-To: stange@rentec.com +Organization: Renaissance Technologies Corp. +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Luke Lonergan <llonergan@greenplum.com> +CC: Dave Cramer <pg@fastcrypt.com>, Greg Stark <gsstark@mit.edu>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA3553F.1406D%llonergan@greenplum.com> +In-Reply-To: <BFA3553F.1406D%llonergan@greenplum.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jAIIU1Qe000149 at Fri Nov 18 + 13:30:02 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.021 required=5 tests=[AWL=0.021] +X-Spam-Score: 0.021 +X-Spam-Level: +X-Archive-Number: 200511/365 +X-Sequence-Number: 15622 + +Luke Lonergan wrote: +> Alan, +> +> On 11/18/05 9:31 AM, "Alan Stange" <stange@rentec.com> wrote: +> +> +>> Here's the output from one iteration of iostat -k 60 while the box is +>> doing a select count(1) on a 238GB table. +>> +>> avg-cpu: %user %nice %sys %iowait %idle +>> 0.99 0.00 17.97 32.40 48.64 +>> +>> Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn +>> sdd 345.95 130732.53 0.00 7843952 0 +>> +>> We're reading 130MB/s for a full minute. About 20% of a single cpu was +>> being used. The remainder being idle. +>> +> +> Cool - thanks for the results. Is that % of one CPU, or of 2? Was the +> system otherwise idle? +> +Actually, this was dual cpu and there was other activity during the full +minute, but it was on other file devices, which I didn't include in the +above output. Given that, and given what I see on the box now I'd +raise the 20% to 30% just to be more conservative. It's all in the +kernel either way; using a different scheduler or file system would +change that result. Even better would be using direct IO to not flush +everything else from memory and avoid some memory copies from kernel to +user space. Note that almost none of the time is user time. Changing +postgresql won't change the cpu useage. + +One IMHO obvious improvement would be to have vacuum and analyze only do +direct IO. Now they appear to be very effective memory flushing tools. +Table scans on tables larger than say 4x memory should probably also use +direct IO for reads. + +> +> +>> We've done nothing fancy and achieved results you claim shouldn't be +>> possible. This is a system that was re-installed yesterday, no tuning +>> was done to the file systems, kernel or storage array. +>> +> +> Are you happy with 130MB/s? How much did you pay for that? Is it more than +> $2,000, or double my 2003 PC? +> +I don't know what the system cost. It was part of block of dual +opterons from Sun that we got some time ago. I think the 130MB/s is +slow given the hardware, but it's acceptable. I'm not too price +sensitive; I care much more about reliability, uptime, etc. + +> +> +>> What am I doing wrong? +>> +>> 9 years ago I co-designed a petabyte data store with a goal of 1GB/s IO +>> (for a DOE lab). And now I don't know what I'm doing, +>> +> Cool. Would that be Sandia? +> +> We routinely sustain 2,000 MB/s from disk on 16x 2003 era machines on +> complex queries. +Disk?! 4 StorageTek tape silos. That would be .002 TB/s. One has to +change how you think when you have that much data. And hope you don't +have a fire, because there's no backup. That work was while I was at +BNL. I believe they are now at 4PB of tape and 150TB of disk. + +-- Alan + +From pgsql-performance-owner@postgresql.org Fri Nov 18 15:31:01 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 38581DBAE2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 14:52:47 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 71206-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 18:52:46 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw02.mi8.com [63.240.6.46]) + by svr1.postgresql.org (Postfix) with ESMTP id 26309DBAAF + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 14:52:43 -0400 (AST) +Received: from 172.16.1.110 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D2)); Fri, 18 Nov 2005 13:52:37 -0500 +X-Server-Uuid: 7829E76E-BB9E-4995-8473-3C0929DF7DD1 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 13:52:37 -0500 +Received: from 67.103.45.218 ([67.103.45.218]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.105]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 13:52:36 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 10:52:35 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: stange@rentec.com +cc: "Dave Cramer" <pg@fastcrypt.com>, "Greg Stark" <gsstark@mit.edu>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-ID: <BFA362F3.14099%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsbnv0jIiZ3fkOQmaD0q3VF1sjeQAAsEeu +In-Reply-To: <437E1DAE.1070301@rentec.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 18 Nov 2005 18:52:37.0123 (UTC) + FILETIME=[3E564D30:01C5EC71] +X-WSS-ID: 6F60FD7F2RS9631979-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.253 required=5 tests=[AWL=0.000, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.253 +X-Spam-Level: * +X-Archive-Number: 200511/368 +X-Sequence-Number: 15625 + +Alan, + +On 11/18/05 10:30 AM, "Alan Stange" <stange@rentec.com> wrote: + +> Actually, this was dual cpu and there was other activity during the full +> minute, but it was on other file devices, which I didn't include in the +> above output. Given that, and given what I see on the box now I'd +> raise the 20% to 30% just to be more conservative. It's all in the +> kernel either way; using a different scheduler or file system would +> change that result. Even better would be using direct IO to not flush +> everything else from memory and avoid some memory copies from kernel to +> user space. Note that almost none of the time is user time. Changing +> postgresql won't change the cpu useage. + +These are all things that help on the IO wait side possibly, however, there +is a producer/consumer problem in postgres that goes something like this: + +- Read some (small number of, sometimes 1) 8k pages +- Do some work on those pages, including lots of copies +- repeat + +This back and forth without threading (like AIO, or a multiprocessing +executor) causes cycling and inefficiency that limits throughput. +Optimizing some of the memcopies and other garbage out, plus increasing the +internal (postgres) readahead would probably double the disk bandwidth. + +But to be disk-bound (meaning that the disk subsystem is running at full +speed), requires asynchronous I/O. We do this now with Bizgres MPP, and we +get fully saturated disk channels on every machine. That means that even on +one machine, we run many times faster than non-MPP postgres. + +> One IMHO obvious improvement would be to have vacuum and analyze only do +> direct IO. Now they appear to be very effective memory flushing tools. +> Table scans on tables larger than say 4x memory should probably also use +> direct IO for reads. + +That's been suggested many times prior - I agree, but this also needs AIO to +be maximally effective. + +> I don't know what the system cost. It was part of block of dual +> opterons from Sun that we got some time ago. I think the 130MB/s is +> slow given the hardware, but it's acceptable. I'm not too price +> sensitive; I care much more about reliability, uptime, etc. + +Then I know what they cost - we have them too (V20z and V40z). You should +be getting 400MB/s+ with external RAID. + +>>> What am I doing wrong? +>>> +>>> 9 years ago I co-designed a petabyte data store with a goal of 1GB/s IO +>>> (for a DOE lab). And now I don't know what I'm doing, +>>> +>> Cool. Would that be Sandia? +>> +>> We routinely sustain 2,000 MB/s from disk on 16x 2003 era machines on +>> complex queries. +> Disk?! 4 StorageTek tape silos. That would be .002 TB/s. One has to +> change how you think when you have that much data. And hope you don't +> have a fire, because there's no backup. That work was while I was at +> BNL. I believe they are now at 4PB of tape and 150TB of disk. + +We had 1.5 Petabytes on 2 STK Silos at NAVO from 1996-1998 where I ran R&D. +We also had a Cray T932 an SGI Origin 3000 with 256 CPUs, a Cray T3E with +1280 CPUs, 2 Cray J916s with 1 TB of shared disk, a Cray C90-16, a Sun E10K, +etc etc, along with clusters of Alpha machines and lots of SGIs. It's nice +to work with a $40M annual budget. + +Later, working with FSL we implemented a weather forecasting cluster that +ultimately became the #5 fastest computer on the TOP500 supercomputing list +from 512 Alpha cluster nodes. That machine had a 10-way shared SAN, tape +robotics and a Myrinet interconnect and ran 64-bit Linux (in 1998). + +- Luke + + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 15:30:40 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 23C48DBAE2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 15:07:49 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 73468-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 19:07:48 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from stark.xeocode.com (stark.xeocode.com [216.58.44.227]) + by svr1.postgresql.org (Postfix) with ESMTP id 7E10DDB9B5 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 15:07:46 -0400 (AST) +Received: from localhost ([127.0.0.1] helo=stark.xeocode.com) + by stark.xeocode.com with smtp (Exim 3.36 #1 (Debian)) + id 1EdBaB-0008En-00; Fri, 18 Nov 2005 14:07:35 -0500 +To: stange@rentec.com +Cc: Luke Lonergan <llonergan@greenplum.com>, Dave Cramer <pg@fastcrypt.com>, + Greg Stark <gsstark@mit.edu>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA3553F.1406D%llonergan@greenplum.com> + <437E1DAE.1070301@rentec.com> +In-Reply-To: <437E1DAE.1070301@rentec.com> +From: Greg Stark <gsstark@mit.edu> +Organization: The Emacs Conspiracy; member since 1992 +Date: 18 Nov 2005 14:07:34 -0500 +Message-ID: <87oe4hpyfd.fsf@stark.xeocode.com> +Lines: 58 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/367 +X-Sequence-Number: 15624 + +Alan Stange <stange@rentec.com> writes: + +> Luke Lonergan wrote: +> > Alan, +> > +> > On 11/18/05 9:31 AM, "Alan Stange" <stange@rentec.com> wrote: +> > +> > +> >> Here's the output from one iteration of iostat -k 60 while the box is +> >> doing a select count(1) on a 238GB table. +> >> +> >> avg-cpu: %user %nice %sys %iowait %idle +> >> 0.99 0.00 17.97 32.40 48.64 +> >> +> >> Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn +> >> sdd 345.95 130732.53 0.00 7843952 0 +> >> +> >> We're reading 130MB/s for a full minute. About 20% of a single cpu was +> >> being used. The remainder being idle. +> >> +> > +> > Cool - thanks for the results. Is that % of one CPU, or of 2? Was the +> > system otherwise idle? +> > +> Actually, this was dual cpu + +I hate to agree with him but that looks like a dual machine with one CPU +pegged. Yes most of the time is being spent in the kernel, but you're still +basically cpu limited. + +That said, 130MB/s is nothing to sneeze at, that's maxing out two high end +drives and quite respectable for a 3-disk stripe set, even reasonable for a +4-disk stripe set. If you're using 5 or more disks in RAID-0 or RAID 1+0 and +only getting 130MB/s then it does seem likely the cpu is actually holding you +back here. + +Still it doesn't show Postgres being nearly so CPU wasteful as the original +poster claimed. + +> It's all in the kernel either way; using a different scheduler or file +> system would change that result. Even better would be using direct IO to not +> flush everything else from memory and avoid some memory copies from kernel +> to user space. Note that almost none of the time is user time. Changing +> postgresql won't change the cpu useage. + +Well changing to direct i/o would still be changing Postgres so that's +unclear. And there are plenty of more mundane ways that Postgres is +responsible for how efficiently or not the kernel is used. Just using fewer +syscalls to do the same amount of reading would reduce cpu consumption. + + +> One IMHO obvious improvement would be to have vacuum and analyze only do direct +> IO. Now they appear to be very effective memory flushing tools. Table scans +> on tables larger than say 4x memory should probably also use direct IO for +> reads. + +-- +greg + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 15:30:18 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CF15FDBA3F + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 15:25:02 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 77967-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 19:25:02 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id 6E4D7DBACA + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 15:24:58 -0400 (AST) +Received: from 172.16.1.110 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Fri, 18 Nov 2005 14:24:49 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 14:24:49 -0500 +Received: from 67.103.45.218 ([67.103.45.218]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.105]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 14:24:49 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 11:24:48 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Greg Stark" <gsstark@mit.edu>, + stange@rentec.com +cc: "Dave Cramer" <pg@fastcrypt.com>, "Joshua Marsh" <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Message-ID: <BFA36A80.140AE%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsc2f8fcfu6PTQRrGGWWqW2mECvgAAlU+z +In-Reply-To: <87oe4hpyfd.fsf@stark.xeocode.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 18 Nov 2005 19:24:49.0694 (UTC) + FILETIME=[BE3D3BE0:01C5EC75] +X-WSS-ID: 6F60F50B31S14707789-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.253 required=5 tests=[AWL=0.000, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.253 +X-Spam-Level: * +X-Archive-Number: 200511/366 +X-Sequence-Number: 15623 + +Greg, + +On 11/18/05 11:07 AM, "Greg Stark" <gsstark@mit.edu> wrote: + +> That said, 130MB/s is nothing to sneeze at, that's maxing out two high end +> drives and quite respectable for a 3-disk stripe set, even reasonable for a +> 4-disk stripe set. If you're using 5 or more disks in RAID-0 or RAID 1+0 and +> only getting 130MB/s then it does seem likely the cpu is actually holding you +> back here. + +With an FC array, it's undoubtedly more like 14 drives, in which case +130MB/s is laughable. On the other hand, I wouldn't be surprised if it were +a single 200MB/s Fibre Channel attachment. + +It does make you wonder why people keep recommending 15K RPM drives, like it +would help *not*. + +> Still it doesn't show Postgres being nearly so CPU wasteful as the original +> poster claimed. + +It's partly about waste, and partly about lack of a concurrent I/O +mechanism. We've profiled it for the waste, we've implemented concurrent +I/O to prove the other point. + +>> It's all in the kernel either way; using a different scheduler or file +>> system would change that result. Even better would be using direct IO to not +>> flush everything else from memory and avoid some memory copies from kernel +>> to user space. Note that almost none of the time is user time. Changing +>> postgresql won't change the cpu useage. +> +> Well changing to direct i/o would still be changing Postgres so that's +> unclear. And there are plenty of more mundane ways that Postgres is +> responsible for how efficiently or not the kernel is used. Just using fewer +> syscalls to do the same amount of reading would reduce cpu consumption. + +Bingo. + +- Luke + + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 15:42:51 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 58A19DB9B5 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 15:39:50 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 79634-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 19:39:50 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id 6F7F5DBAF8 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 15:39:47 -0400 (AST) +Received: from wren.rentec.com (wren.rentec.com [192.5.35.106]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jAIJdPsN003091 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Fri, 18 Nov 2005 14:39:26 -0500 (EST) +X-Source: non-mednet +Received: from [172.26.132.145] (hoopoe.rentec.com [172.26.132.145]) + by wren.rentec.com (8.13.1/8.12.1) with ESMTP id jAIJdUGC005577; + Fri, 18 Nov 2005 14:39:31 -0500 (EST) +Message-ID: <437E2DF2.50906@rentec.com> +Date: Fri, 18 Nov 2005 14:39:30 -0500 +From: Alan Stange <stange@rentec.com> +Reply-To: stange@rentec.com +Organization: Renaissance Technologies Corp. +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Greg Stark <gsstark@mit.edu> +CC: Luke Lonergan <llonergan@greenplum.com>, Dave Cramer <pg@fastcrypt.com>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA3553F.1406D%llonergan@greenplum.com> + <437E1DAE.1070301@rentec.com> + <87oe4hpyfd.fsf@stark.xeocode.com> +In-Reply-To: <87oe4hpyfd.fsf@stark.xeocode.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jAIJdPsN003091 at Fri Nov 18 + 14:39:26 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.017 required=5 tests=[AWL=0.017] +X-Spam-Score: 0.017 +X-Spam-Level: +X-Archive-Number: 200511/371 +X-Sequence-Number: 15628 + +Greg Stark wrote: +> Alan Stange <stange@rentec.com> writes: +> +> +>> Luke Lonergan wrote: +>> +>>> Alan, +>>> +>>> On 11/18/05 9:31 AM, "Alan Stange" <stange@rentec.com> wrote: +>>> +>>> +>>> +>>>> Here's the output from one iteration of iostat -k 60 while the box is +>>>> doing a select count(1) on a 238GB table. +>>>> +>>>> avg-cpu: %user %nice %sys %iowait %idle +>>>> 0.99 0.00 17.97 32.40 48.64 +>>>> +>>>> Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn +>>>> sdd 345.95 130732.53 0.00 7843952 0 +>>>> +>>>> We're reading 130MB/s for a full minute. About 20% of a single cpu was +>>>> being used. The remainder being idle. +>>>> +>>>> +>>> Cool - thanks for the results. Is that % of one CPU, or of 2? Was the +>>> system otherwise idle? +>>> +>>> +>> Actually, this was dual cpu +>> +> +> I hate to agree with him but that looks like a dual machine with one CPU +> pegged. Yes most of the time is being spent in the kernel, but you're still +> basically cpu limited. +> +> That said, 130MB/s is nothing to sneeze at, that's maxing out two high end +> drives and quite respectable for a 3-disk stripe set, even reasonable for a +> 4-disk stripe set. If you're using 5 or more disks in RAID-0 or RAID 1+0 and +> only getting 130MB/s then it does seem likely the cpu is actually holding you +> back here. +> +> Still it doesn't show Postgres being nearly so CPU wasteful as the original +> poster claimed. +> +Yes and no. The one cpu is clearly idle. The second cpu is 40% busy +and 60% idle (aka iowait in the above numbers). +Of that 40%, other things were happening as well during the 1 minute +snapshot. During some iostat outputs that I didn't post the cpu time +was ~ 20%. + +So, you can take your pick. The single cpu usage is somewhere between +20% and 40%. As I can't remove other users of the system, it's the best +measurement that I can make right now. + +Either way, it's not close to being cpu bound. This is with Opteron +248, 2.2Ghz cpus. + +Note that the storage system has been a bit disappointing: it's an IBM +Fast T600 with a 200MB/s fiber attachment. It could be better, but +it's not been the bottleneck in our work, so we haven't put any energy +into it. + +>> It's all in the kernel either way; using a different scheduler or file +>> system would change that result. Even better would be using direct IO to not +>> flush everything else from memory and avoid some memory copies from kernel +>> to user space. Note that almost none of the time is user time. Changing +>> postgresql won't change the cpu useage. +>> +> Well changing to direct i/o would still be changing Postgres so that's +> unclear. And there are plenty of more mundane ways that Postgres is +> responsible for how efficiently or not the kernel is used. Just using fewer +> syscalls to do the same amount of reading would reduce cpu consumption. +Absolutely. This is why we're using a 32KB block size and also switched +to using O_SYNC for the WAL syncing method. That's many MB/s that +don't need to be cached in the kernel (thus evicting other data), and we +avoid all the fysnc/fdatasync syscalls. + +The purpose of direct IO isn't to make the vacuum or analyze faster, but +to lessen their impact on queries with someone waiting for the +results. That's our biggest hit: running a sequential scan on 240GB +of data and flushing everything else out of memory. + +Now that I'm think about this a bit, a big chunk of time is probably +being lost in TLB misses and other virtual memory events that would be +avoided if a larger page size was being used. + +-- Alan + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 15:42:15 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id DB093DBABC + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 15:40:13 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 79805-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 19:40:13 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id 38A0DDBAAE + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 15:40:10 -0400 (AST) +Received: from wren.rentec.com (wren.rentec.com [192.5.35.106]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jAIJdi34003102 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Fri, 18 Nov 2005 14:39:45 -0500 (EST) +X-Source: non-mednet +Received: from [172.26.132.145] (hoopoe.rentec.com [172.26.132.145]) + by wren.rentec.com (8.13.1/8.12.1) with ESMTP id jAIJdoYx005594; + Fri, 18 Nov 2005 14:39:50 -0500 (EST) +Message-ID: <437E2E06.5070306@rentec.com> +Date: Fri, 18 Nov 2005 14:39:50 -0500 +From: Alan Stange <stange@rentec.com> +Reply-To: stange@rentec.com +Organization: Renaissance Technologies Corp. +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Luke Lonergan <llonergan@greenplum.com> +CC: Dave Cramer <pg@fastcrypt.com>, Greg Stark <gsstark@mit.edu>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA362F3.14099%llonergan@greenplum.com> +In-Reply-To: <BFA362F3.14099%llonergan@greenplum.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jAIJdi34003102 at Fri Nov 18 + 14:39:45 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.016 required=5 tests=[AWL=0.016] +X-Spam-Score: 0.016 +X-Spam-Level: +X-Archive-Number: 200511/370 +X-Sequence-Number: 15627 + +Luke Lonergan wrote: +>> opterons from Sun that we got some time ago. I think the 130MB/s is +>> slow given the hardware, but it's acceptable. I'm not too price +>> sensitive; I care much more about reliability, uptime, etc. +>> +> I don't know what the system cost. It was part of block of dual +> +> Then I know what they cost - we have them too (V20z and V40z). You should +> be getting 400MB/s+ with external RAID. +Yes, but we don't. This is where I would normally begin a rant on how +craptacular Linux can be at times. But, for the sake of this +discussion, postgresql isn't reading the data any more slowly than does +any other program. + +And we don't have the time to experiment with the box. + +I know it should be better, but it's good enough for our purposes at +this time. + +-- Alan + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 16:29:22 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id C00DDDBB5F + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 16:29:20 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 87345-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 20:29:20 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtpauth06.mail.atl.earthlink.net + (smtpauth06.mail.atl.earthlink.net [209.86.89.66]) + by svr1.postgresql.org (Postfix) with ESMTP id 32394DBB43 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 16:29:17 -0400 (AST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; + d=earthlink.net; + b=UMKgMxx0sApZ1H1VfjR1KLvvXrtPJQiRfG8prl+EsjGL1B0W3iWBtT2Qt2E1O8Wb; + h=Received:Message-Id:X-Mailer:Date:To:From:Subject:In-Reply-To:References:Mime-Version:Content-Type:Content-Transfer-Encoding:X-ELNK-Trace:X-Originating-IP; +Received: from [71.243.20.20] (helo=ron-6d52adff2a6.earthlink.net) + by smtpauth06.mail.atl.earthlink.net with asmtp (Exim 4.34) + id 1EdCrE-0004mC-TL; Fri, 18 Nov 2005 15:29:17 -0500 +Message-Id: <6.2.5.6.0.20051118151319.01d16288@earthlink.net> +X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6 +Date: Fri, 18 Nov 2005 15:29:11 -0500 +To: "Luke Lonergan" <llonergan@greenplum.com>, + pgsql-performance@postgresql.org +From: Ron <rjpeace@earthlink.net> +Subject: Re: Hardware/OS recommendations for large databases +In-Reply-To: <BFA32FA6.14027%llonergan@greenplum.com> +References: <0F3B99E2-4575-42B8-8AAC-3FE4B231348C@fastcrypt.com> + <BFA32FA6.14027%llonergan@greenplum.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset="iso-8859-1"; format=flowed +Content-Transfer-Encoding: quoted-printable +X-ELNK-Trace: + acd68a6551193be5d780f4a490ca69563f9fea00a6dd62bc48f667b06784056006e7b606f77b12d1350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c +X-Originating-IP: 71.243.20.20 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.359 required=5 tests=[AWL=-0.120, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.359 +X-Spam-Level: +X-Archive-Number: 200511/380 +X-Sequence-Number: 15637 + +Breaking the ~120MBps pg IO ceiling by any means=20 +is an important result. Particularly when you=20 +get a ~2x improvement. I'm curious how far we=20 +can get using simple approaches like this. + +At 10:13 AM 11/18/2005, Luke Lonergan wrote: +>Dave, +> +>On 11/18/05 5:00 AM, "Dave Cramer" <pg@fastcrypt.com> wrote: +> > +> > Now there's an interesting line drawn in the sand. I presume you have +> > numbers to back this up ? +> > +> > This should draw some interesting posts. +> +>Part 2: The answer +> +>System A: +>This system is running RedHat 3 Update 4, with a Fedora 2.6.10 Linux= + kernel. +> +>On a single table with 15 columns (the Bizgres=20 +>IVP) at a size double memory (2.12GB), Postgres=20 +>8.0.3 with Bizgres enhancements takes 32 seconds=20 +>to scan the table: that=92s 66 MB/s. Not the=20 +>efficiency I=92d hope from the onboard SATA=20 +>controller that I=92d like, I would have expected=20 +>to get 85% of the 100MB/s raw read performance. +Have you tried the large read ahead trick with=20 +this system? It would be interesting to see how=20 +much it would help. It might even be worth it to=20 +do the experiment at all of [default, 2x default,=20 +4x default, 8x default, etc] read ahead until=20 +either a) you run out of resources to support the=20 +desired read ahead, or b) performance levels=20 +off. I can imagine the results being very enlightening. + + +>System B: +>This system is running an XFS filesystem, and=20 +>has been tuned to use very large (16MB)=20 +>readahead. It=92s running the Centos 4.1 distro,=20 +>which uses a Linux 2.6.9 kernel. +> +>Same test as above, but with 17GB of data takes=20 +>69.7 seconds to scan (!) That=92s 244.2MB/s,=20 +>which is obviously double my earlier point of=20 +>110-120MB/s. This system is running with a 16MB=20 +>Linux readahead setting, let=92s try it with the=20 +>default (I think) setting of 256KB =96 AHA! Now we get 171.4 seconds or= + 99.3MB/s. +The above experiment would seem useful here as well. + + +>Summary: +> +><cough, cough> OK =96 you can get more I/O=20 +>bandwidth out of the current I/O path for=20 +>sequential scan if you tune the filesystem for=20 +>large readahead. This is a cheap alternative to=20 +>overhauling the executor to use asynch I/O. +> +>Still, there is a CPU limit here =96 this is not=20 +>I/O bound, it is CPU limited as evidenced by the=20 +>sensitivity to readahead settings. If the=20 +>filesystem could do 1GB/s, you wouldn=92t go any faster than 244MB/s. +> +>- Luke + +I respect your honesty in reporting results that=20 +were different then your expectations or=20 +previously taken stance. Alan Stange's comment=20 +re: the use of direct IO along with your comments=20 +re: async IO and mem copies plus the results of=20 +these experiments could very well point us=20 +directly at how to most easily solve pg's CPU boundness during IO. + +[HACKERS] are you watching this? + +Ron + + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 19:46:57 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 2ADB4DBAE6 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 19:46:56 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 08330-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 23:46:58 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from linda-5.paradise.net.nz (bm-5a.paradise.net.nz + [203.96.152.184]) + by svr1.postgresql.org (Postfix) with ESMTP id 931F9DB9FA + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 19:46:53 -0400 (AST) +Received: from smtp-1.paradise.net.nz + (tclsnelb2-src-1.paradise.net.nz [203.96.152.177]) by + linda-5.paradise.net.nz (Paradise.net.nz) with ESMTP id + <0IQ600J49CQ8SS@linda-5.paradise.net.nz> for + pgsql-performance@postgresql.org; Sat, 19 Nov 2005 12:46:56 +1300 (NZDT) +Received: from [192.168.1.11] (218-101-29-15.dsl.clear.net.nz [218.101.29.15]) + by smtp-1.paradise.net.nz (Postfix) with ESMTP id 7BCC010DA585; Sat, + 19 Nov 2005 12:46:55 +1300 (NZDT) +Date: Sat, 19 Nov 2005 12:46:54 +1300 +From: Mark Kirkwood <markir@paradise.net.nz> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <BFA32FA6.14027%llonergan@greenplum.com> +To: Luke Lonergan <llonergan@greenplum.com> +Cc: Dave Cramer <pg@fastcrypt.com>, Greg Stark <gsstark@mit.edu>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-id: <437E67EE.4070605@paradise.net.nz> +MIME-version: 1.0 +Content-type: text/plain; charset=windows-1252; format=flowed +Content-transfer-encoding: 8BIT +X-Accept-Language: en-us, en +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20051106) +References: <BFA32FA6.14027%llonergan@greenplum.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.332 required=5 tests=[RCVD_IN_BL_SPAMCOP_NET=1.332] +X-Spam-Score: 1.332 +X-Spam-Level: * +X-Archive-Number: 200511/384 +X-Sequence-Number: 15641 + +Luke Lonergan wrote: + +> (mass snippage) +> time psql -c "select count(*) from ivp.bigtable1" dgtestdb +> [llonergan@modena2 IVP]$ cat sysout3 +> count +> ---------- +> 80000000 +> (1 row) +> +> +> real 1m9.875s +> user 0m0.000s +> sys 0m0.004s +> [llonergan@modena2 IVP]$ !du +> du -sk dgtestdb/base +> 17021260 dgtestdb/base +> +> +> Summary: +> +> <cough, cough> OK � you can get more I/O bandwidth out of the current +> I/O path for sequential scan if you tune the filesystem for large +> readahead. This is a cheap alternative to overhauling the executor to +> use asynch I/O. +> +> Still, there is a CPU limit here � this is not I/O bound, it is CPU +> limited as evidenced by the sensitivity to readahead settings. If the +> filesystem could do 1GB/s, you wouldn�t go any faster than 244MB/s. +> +> + +Luke, + +Interesting - but possibly only representative for a workload consisting +entirely of one executor doing "SELECT ... FROM my_single_table". + +If you alter this to involve more complex joins (e.g 4. way star) and +(maybe add a small number of concurrent executors too) - is it still the +case? + +Cheers + +Mark + +From pgsql-performance-owner@postgresql.org Fri Nov 18 20:04:10 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8C795DBB3F + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 20:04:08 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 10302-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 00:04:10 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id 9A4DDDBB1E + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 20:04:05 -0400 (AST) +Received: from 172.16.1.110 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Fri, 18 Nov 2005 19:04:02 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 19:04:02 -0500 +Received: from 67.103.45.218 ([67.103.45.218]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.105]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 19:04:01 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 16:04:00 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Mark Kirkwood" <markir@paradise.net.nz> +cc: "Dave Cramer" <pg@fastcrypt.com>, "Greg Stark" <gsstark@mit.edu>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-ID: <BFA3ABF0.14124%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsmmQi55EBnDCuTAK/LsJ/SGHiVAAAloQR +In-Reply-To: <437E67EE.4070605@paradise.net.nz> +MIME-Version: 1.0 +X-OriginalArrivalTime: 19 Nov 2005 00:04:02.0506 (UTC) + FILETIME=[BFB17AA0:01C5EC9C] +X-WSS-ID: 6F60B47831S14976722-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.253 required=5 tests=[AWL=0.000, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.253 +X-Spam-Level: * +X-Archive-Number: 200511/385 +X-Sequence-Number: 15642 + +Mark, + +On 11/18/05 3:46 PM, "Mark Kirkwood" <markir@paradise.net.nz> wrote: + +> If you alter this to involve more complex joins (e.g 4. way star) and +> (maybe add a small number of concurrent executors too) - is it still the +> case? + +4-way star, same result, that's part of my point. With Bizgres MPP, the +4-way star uses 4 concurrent scanners, though not all are active all the +time. And that's per segment instance - we normally use one segment +instance per CPU, so our concurrency is NCPUs plus some. + +The trick is the "small number of concurrent executors" part. The only way +to get this with normal postgres is to have concurrent users, and normally +they are doing different things, scanning different parts of the disk. +These are competing things, and for concurrency enhancement something like +"sync scan" would be an effective optimization. + +But in reporting, business analytics and warehousing in general, there are +reports that take hours to run. If you can knock that down by factors of 10 +using parallelism, it's a big win. That's the reason that Teradata did $1.5 +Billion in business last year. + +More importantly - that's the kind of work that everyone using internet data +for analytics wants right now. + +- Luke + + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 20:06:10 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D43C3DBB34 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 20:06:08 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 11939-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 00:06:10 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id 09D9FDBB3A + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 20:06:05 -0400 (AST) +Received: from 172.16.1.110 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Fri, 18 Nov 2005 19:06:01 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 18 Nov + 2005 19:06:01 -0500 +Received: from 67.103.45.218 ([67.103.45.218]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.105]) with Microsoft Exchange Server HTTP-DAV ; Fri, 18 Nov + 2005 19:06:01 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Fri, 18 Nov 2005 16:05:59 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Mark Kirkwood" <markir@paradise.net.nz> +cc: "Dave Cramer" <pg@fastcrypt.com>, "Greg Stark" <gsstark@mit.edu>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-ID: <BFA3AC67.14125%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXsmmQi55EBnDCuTAK/LsJ/SGHiVAAAqD/h +In-Reply-To: <437E67EE.4070605@paradise.net.nz> +MIME-Version: 1.0 +X-OriginalArrivalTime: 19 Nov 2005 00:06:01.0725 (UTC) + FILETIME=[06C0DAD0:01C5EC9D] +X-WSS-ID: 6F60B3E331S14978187-01-01 +Content-Type: multipart/alternative; + boundary=B_3215174759_3942834 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.254 required=5 tests=[AWL=-0.000, + HTML_MESSAGE=0.001, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.254 +X-Spam-Level: * +X-Archive-Number: 200511/386 +X-Sequence-Number: 15643 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3215174759_3942834 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Mark, + +On 11/18/05 3:46 PM, "Mark Kirkwood" <markir@paradise.net.nz> wrote: + +> If you alter this to involve more complex joins (e.g 4. way star) and +> (maybe add a small number of concurrent executors too) - is it still the +> case? + +I may not have listened to you - are you asking about whether the readahead +works for these cases? + +I=B9ll be running some massive TPC-H benchmarks on these machines soon =AD we=B9l= +l +see then. + +- Luke + +--B_3215174759_3942834 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +<HTML> +<HEAD> +<TITLE>Re: [PERFORM] Hardware/OS recommendations for large databases (</TIT= +LE> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Mark,= +<BR> +<BR> +On 11/18/05 3:46 PM, "Mark Kirkwood" <markir@paradise.net.nz&g= +t; wrote:<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>If you alter this to involve more complex joins (e.g 4.= + way star) and<BR> +(maybe add a small number of concurrent executors too) - is it still the<BR= +> +case?<BR> +</SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= +LE=3D'font-size:14.0px'><BR> +I may not have listened to you - are you asking about whether the readahead= + works for these cases?<BR> +<BR> +I’ll be running some massive TPC-H benchmarks on these machines soon = +– we’ll see then.<BR> +<BR> +- Luke</SPAN></FONT> +</BODY> +</HTML> + + +--B_3215174759_3942834-- + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 20:06:25 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 7644AD82C0 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 20:06:22 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 10242-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 00:06:24 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id C847FD6D50 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 20:06:19 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAJ06LXL013281; + Fri, 18 Nov 2005 19:06:21 -0500 (EST) +To: "Virag Saksena" <v_saks@hotmail.com> +cc: pgsql-performance@postgresql.org +Subject: Re: ERROR: no value found for parameter 1 with JDBC and Explain + Analyze +In-reply-to: <BAY103-F11ECB17126271926CB8DE1EC5D0@phx.gbl> +References: <BAY103-F11ECB17126271926CB8DE1EC5D0@phx.gbl> +Comments: In-reply-to "Virag Saksena" <v_saks@hotmail.com> + message dated "Tue, 15 Nov 2005 10:06:33 +0000" +Date: Fri, 18 Nov 2005 19:06:20 -0500 +Message-ID: <13280.1132358780@sss.pgh.pa.us> +From: Tom Lane <tgl@sss.pgh.pa.us> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.005 required=5 tests=[AWL=0.005] +X-Spam-Score: 0.005 +X-Spam-Level: +X-Archive-Number: 200511/387 +X-Sequence-Number: 15644 + +"Virag Saksena" <v_saks@hotmail.com> writes: +> ERROR: no value found for parameter 1 + +> Here is sample code which causes this exception ... +> pst=prodconn.prepareStatement("explain analyze select count(*) from +> jam_heaprel r where heap_id = ? and parentaddr = ?"); + +I don't think EXPLAIN can take parameters (most of the "utility" +statements don't take parameters). + +The usual workaround is to use PREPARE: + + PREPARE foo(paramtype,paramtype) AS SELECT ...; + EXPLAIN EXECUTE foo(x,y); + +This will generate the same parameterized plan as you'd get from the +other way, so it's a reasonable approximation to the behavior with +JDBC parameters. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 18 22:27:51 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5DEF9DBB20 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 22:27:50 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 24899-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 02:27:53 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from linda-3.paradise.net.nz (bm-3a.paradise.net.nz + [203.96.152.182]) + by svr1.postgresql.org (Postfix) with ESMTP id C02DADBAC8 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 22:27:47 -0400 (AST) +Received: from smtp-2.paradise.net.nz + (tclsnelb2-src-1.paradise.net.nz [203.96.152.177]) by + linda-3.paradise.net.nz (Paradise.net.nz) with ESMTP id + <0IQ6004RJK6FAK@linda-3.paradise.net.nz> for + pgsql-performance@postgresql.org; Sat, 19 Nov 2005 15:27:51 +1300 (NZDT) +Received: from [192.168.1.11] (218-101-29-15.dsl.clear.net.nz [218.101.29.15]) + by smtp-2.paradise.net.nz (Postfix) with ESMTP id 2249BC3DC2F; Sat, + 19 Nov 2005 15:27:51 +1300 (NZDT) +Date: Sat, 19 Nov 2005 15:27:49 +1300 +From: Mark Kirkwood <markir@paradise.net.nz> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <BFA3AC67.14125%llonergan@greenplum.com> +To: Luke Lonergan <llonergan@greenplum.com> +Cc: Dave Cramer <pg@fastcrypt.com>, Greg Stark <gsstark@mit.edu>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-id: <437E8DA5.1050703@paradise.net.nz> +MIME-version: 1.0 +Content-type: text/plain; charset=windows-1252; format=flowed +Content-transfer-encoding: 8BIT +X-Accept-Language: en-us, en +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20051106) +References: <BFA3AC67.14125%llonergan@greenplum.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.332 required=5 tests=[RCVD_IN_BL_SPAMCOP_NET=1.332] +X-Spam-Score: 1.332 +X-Spam-Level: * +X-Archive-Number: 200511/388 +X-Sequence-Number: 15645 + +Luke Lonergan wrote: +> Mark, +> +> On 11/18/05 3:46 PM, "Mark Kirkwood" <markir@paradise.net.nz> wrote: +> +> If you alter this to involve more complex joins (e.g 4. way star) and +> (maybe add a small number of concurrent executors too) - is it still the +> case? +> +> +> I may not have listened to you - are you asking about whether the +> readahead works for these cases? +> +> I�ll be running some massive TPC-H benchmarks on these machines soon � +> we�ll see then. + + +That too, meaning the business of 1 executor random reading a given +relation file whilst another is sequentially scanning (some other) part +of it.... + +Cheers + +Mark + +From pgsql-performance-owner@postgresql.org Fri Nov 18 23:24:11 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id AA47FD82C0 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 23:24:08 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 32774-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 03:24:12 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 142B3D6D50 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 23:24:06 -0400 (AST) +Received: from hotmail.com (bay106-f29.bay106.hotmail.com [65.54.161.39]) + by svr2.postgresql.org (Postfix) with ESMTP id E47C1F0B37 + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 03:24:10 +0000 (GMT) +Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; + Fri, 18 Nov 2005 19:24:09 -0800 +Message-ID: <BAY106-F29AAEBFDCAA6E044ECFAC6B7510@phx.gbl> +Received: from 65.54.161.200 by by106fd.bay106.hotmail.msn.com with HTTP; + Sat, 19 Nov 2005 03:24:08 GMT +X-Originating-IP: [61.230.36.176] +X-Originating-Email: [anonpermutation@hotmail.com] +X-Sender: anonpermutation@hotmail.com +From: "anon permutation" <anonpermutation@hotmail.com> +To: pgsql-performance@postgresql.org +Subject: What is the max number of database I can create in an instance of + pgsql? +Date: Sat, 19 Nov 2005 03:24:08 +0000 +Mime-Version: 1.0 +Content-Type: text/plain; format=flowed +X-OriginalArrivalTime: 19 Nov 2005 03:24:09.0058 (UTC) + FILETIME=[B427EC20:01C5ECB8] +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.919 required=5 tests=[DNS_FROM_RFC_ABUSE=0.479, + DNS_FROM_RFC_POST=1.44, MSGID_FROM_MTA_HEADER=0] +X-Spam-Score: 1.919 +X-Spam-Level: * +X-Archive-Number: 200511/389 +X-Sequence-Number: 15646 + + +Hi, + +We want to create a database for each one of our departments, but we only +want to have one instance of postgresql running. There are about 10-20 +departments. I can easily use createdb to create these databases. However, +what is the max number of database I can create before performance goes +down? + +Assuming each database is performing well alone, how would putting 10-20 of +them together in one instance affect postgres? + +In terms of getting a new server for this project, how do I gauge how +powerful of a server should I get? + +Thanks. + + + +From pgsql-performance-owner@postgresql.org Fri Nov 18 23:52:55 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 78AF6DB790 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 18 Nov 2005 23:52:53 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 42379-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 03:52:57 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtp-send.myrealbox.com (smtp-send.myrealbox.com + [151.155.5.143]) + by svr1.postgresql.org (Postfix) with ESMTP id F1665D82C0 + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 23:52:50 -0400 (AST) +Received: from [172.16.1.187] grzm [61.197.227.146] + by smtp-send.myrealbox.com with NetMail SMTP Agent $Revision: 1.6 $ on + Linux via secured & encrypted transport (TLS); + Fri, 18 Nov 2005 20:49:46 -0700 +In-Reply-To: <BAY106-F29AAEBFDCAA6E044ECFAC6B7510@phx.gbl> +References: <BAY106-F29AAEBFDCAA6E044ECFAC6B7510@phx.gbl> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: <EEBF2C76-224F-4AB4-985E-2525A5DAA2EF@myrealbox.com> +Cc: pgsql-performance@postgresql.org +Content-Transfer-Encoding: 7bit +From: Michael Glaesemann <grzm@myrealbox.com> +Subject: Re: What is the max number of database I can create in an instance of + pgsql? +Date: Sat, 19 Nov 2005 12:49:43 +0900 +To: "anon permutation" <anonpermutation@hotmail.com> +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.969 required=5 tests=[AWL=-0.363, + RCVD_IN_BL_SPAMCOP_NET=1.332] +X-Spam-Score: 0.969 +X-Spam-Level: +X-Archive-Number: 200511/390 +X-Sequence-Number: 15647 + + +On Nov 19, 2005, at 12:24 , anon permutation wrote: + +> However, what is the max number of database I can create before +> performance goes down? +> +> Assuming each database is performing well alone, how would putting +> 10-20 of them together in one instance affect postgres? +> +> In terms of getting a new server for this project, how do I gauge +> how powerful of a server should I get? + +I'm sure those wiser than me will chime in with specifics. I think +you should be think of usage not in terms of number of databases but +in terms of connections rates, database size (numbers of tables and +tuples) and the types of queries that will be run. While there may be +a little overhead in from having a number of databases in the +cluster, I think this is probably going to be insignificant in +comparison to these other factors. A better idea of what the usage +will guide you in choosing your hardware. + + +Michael Glaesemann +grzm myrealbox com + + + + +From pgsql-performance-owner@postgresql.org Sat Nov 19 00:55:33 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6FE6CDBB8B + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 00:55:31 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 58539-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 04:55:29 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from xproxy.gmail.com (xproxy.gmail.com [66.249.82.207]) + by svr1.postgresql.org (Postfix) with ESMTP id E9840DBB87 + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 00:55:28 -0400 (AST) +Received: by xproxy.gmail.com with SMTP id h30so326787wxd + for <pgsql-performance@postgresql.org>; + Fri, 18 Nov 2005 20:55:26 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=fON/xGlwmOrWOcX/8FqDBoLr1B1fDf9WIiVa1XYGiIPTeWE3L/Penxcq+Rj/EBz5jxr1mHEyNXDKJCriGo/zo9rCz3atbADVoAVhK4xQir8mjyao6vZ3iizw+ZJq9BUNHf52j1Tt0t/+O6PSQ60W+KKfSPRZqY/AofQLGIQXZIw= +Received: by 10.65.15.4 with SMTP id s4mr609076qbi; + Fri, 18 Nov 2005 20:55:26 -0800 (PST) +Received: by 10.65.180.2 with HTTP; Fri, 18 Nov 2005 20:55:26 -0800 (PST) +Message-ID: <c2d9e70e0511182055y79b1e914ybed284840474b632@mail.gmail.com> +Date: Fri, 18 Nov 2005 23:55:26 -0500 +From: Jaime Casanova <systemguards@gmail.com> +To: anon permutation <anonpermutation@hotmail.com> +Subject: Re: What is the max number of database I can create in an instance of + pgsql? +Cc: pgsql-performance@postgresql.org +In-Reply-To: <BAY106-F29AAEBFDCAA6E044ECFAC6B7510@phx.gbl> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <BAY106-F29AAEBFDCAA6E044ECFAC6B7510@phx.gbl> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.4 required=5 tests=[AWL=0.400] +X-Spam-Score: 0.4 +X-Spam-Level: +X-Archive-Number: 200511/391 +X-Sequence-Number: 15648 + +On 11/18/05, anon permutation <anonpermutation@hotmail.com> wrote: +> +> Hi, +> +> We want to create a database for each one of our departments, but we only +> want to have one instance of postgresql running. There are about 10-20 +> departments. I can easily use createdb to create these databases. Howev= +er, +> + +After of doing this, you have to think if you will want to make querys +across the info of some or all databases (and you will) if that is the +case the better you can do is create schemas instead of databases... + +> what is the max number of database I can create before performance goes +> down? +> + +the problem isn't about number of databases but concurrent users... +after all you will have the same resources for 1 or 100 databases, the +important thing is the number of users, the amount of data normal +users will process in a normal day, and complexity of your queries. + +> Assuming each database is performing well alone, how would putting 10-20 = +of +> +> them together in one instance affect postgres? +> +> In terms of getting a new server for this project, how do I gauge how +> powerful of a server should I get? +> +> Thanks. +> +> + + +-- +regards, +Jaime Casanova +(DBA: DataBase Aniquilator ;) + +From pgsql-performance-owner@postgresql.org Sat Nov 19 06:51:53 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 078FBDBBF9 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 06:51:49 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 06609-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 10:51:51 +0000 (GMT) +X-Greylist: delayed 03:05:18.766441 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 34B15DBBD3 + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 06:51:47 -0400 (AST) +Received: from alexwang.com (alexwang.com [220.132.178.72]) + by svr2.postgresql.org (Postfix) with ESMTP id 34773F0B8E + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 07:46:27 +0000 (GMT) +Received: from alexxp ([192.168.0.2]) (authenticated bits=0) + by alexwang.com (8.13.5/8.13.5) with ESMTP id jAJ7kmej017555 + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 15:46:49 +0800 (CST) +Message-ID: <002601c5ecdd$503279e0$0200a8c0@alexxp> +From: "Alex Wang" <alex@alexwang.com> +To: <pgsql-performance@postgresql.org> +Subject: VERY slow after many updates +Date: Sat, 19 Nov 2005 15:46:06 +0800 +MIME-Version: 1.0 +Content-Type: text/plain; format=flowed; charset="big5"; reply-type=original +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2900.2527 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2527 +X-twbsd-MailScanner-Information: Please contact the ISP for more information +X-twbsd-MailScanner: Found to be clean +X-twbsd-MailScanner-From: alex@alexwang.com +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/392 +X-Sequence-Number: 15649 + +I am using PostgreSQL in an embedded system which has only 32 or 64 MB RAM +(run on PPC 266 MHz or ARM 266MHz CPU). I have a table to keep downlaod +tasks. There is a daemon keep looking up the table and fork a new process to +download data from internet. + +Daemon: + . Check the table every 5 seconds + . Fork a download process to download if there is new task +Downlaod process (there are 5 download process max): + . Update the download rate and downloaded size every 3 seconds. + +At begining, everything just fine. The speed is good. But after 24 hours, +the speed to access database become very very slow. Even I stop all +processes, restart PostgreSQL and use psql to select data, this speed is +still very very slow (a SQL command takes more than 2 seconds). It is a +small table. There are only 8 records in the table. + +The only way to solve it is remove all database, run initdb, create new +database and insert new records. I tried to run vacummdb but still very +slow. + +Any idea to make it faster? + +Thanks, +Alex + +-- +Here is the table schema: +create table download_queue ( + task_id SERIAL, + username varchar(128), + pid int, + url text, + filename varchar(1024), + status int, + created_time int, + started_time int, + total_size int8, + current_size int8, + current_rate int, + CONSTRAINT download_queue_pkey PRIMARY KEY(task_id) +); +CREATE INDEX download_queue_user_index ON download_queue USING BTREE +(username); + + + +-- +This message has been scanned for viruses and +dangerous content by MailScanner, and is +believed to be clean. + + +From pgsql-performance-owner@postgresql.org Sat Nov 19 07:12:15 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 303AAD82C0 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 07:12:14 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 07464-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 11:12:16 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.ecircle.de (mail.ecircle.de [195.140.186.200]) + by svr1.postgresql.org (Postfix) with ESMTP id 57656DBB2D + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 07:12:10 -0400 (AST) +Received: from [192.168.1.110] (unknown [192.168.1.110]) + by mail.ecircle.de (READY) with ESMTP id 017949541EC; + Sat, 19 Nov 2005 12:12:13 +0100 (CET) +Subject: Re: VERY slow after many updates +From: Csaba Nagy <nagy@ecircle-ag.com> +To: Alex Wang <alex@alexwang.com> +Cc: postgres performance list <pgsql-performance@postgresql.org> +In-Reply-To: <002601c5ecdd$503279e0$0200a8c0@alexxp> +References: <002601c5ecdd$503279e0$0200a8c0@alexxp> +Content-Type: text/plain +Message-Id: <1132398732.10890.480.camel@coppola.muc.ecircle.de> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) +Date: Sat, 19 Nov 2005 12:12:12 +0100 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/393 +X-Sequence-Number: 15650 + +Alex, + +I suppose the table is a kind of 'queue' table, where you +insert/get/delete continuously, and the life of the records is short. +Considering that in postgres a delete will still leave you the record in +the table's file and in the indexes, just mark it as dead, your table's +actual size can grow quite a lot even if the number of live records will +stay small (you will have a lot of dead tuples, the more tasks +processed, the more dead tuples). So I guess you should vacuum this +table very often, so that the dead tuples are reused. I'm not an expert +on this, but it might be good to vacuum after each n deletions, where n +is ~ half the average size of the queue you expect to have. From time to +time you might want to do a vacuum full on it and a reindex. + +Right now I guess a vacuum full + reindex will help you. I think it's +best to do: + +vacuum download_queue; +vacuum full download_queue; +reindex download_queue; + +I think the non-full vacuum which is less obtrusive than the full one +will do at least some of the work and it will bring all needed things in +FS cache, so the full vacuum to be as fast as possible (vacuum full +locks exclusively the table). At least I do it this way with good +results for small queue-like tables... + +BTW, I wonder if the download_queue_user_index index is helping you at +all on that table ? Do you expect it to grow bigger than 1000 ? +Otherwise it has no point to index it. + +HTH, +Csaba. + +On Sat, 2005-11-19 at 08:46, Alex Wang wrote: +> I am using PostgreSQL in an embedded system which has only 32 or 64 MB RAM +> (run on PPC 266 MHz or ARM 266MHz CPU). I have a table to keep downlaod +> tasks. There is a daemon keep looking up the table and fork a new process to +> download data from internet. +> +> Daemon: +> . Check the table every 5 seconds +> . Fork a download process to download if there is new task +> Downlaod process (there are 5 download process max): +> . Update the download rate and downloaded size every 3 seconds. +> +> At begining, everything just fine. The speed is good. But after 24 hours, +> the speed to access database become very very slow. Even I stop all +> processes, restart PostgreSQL and use psql to select data, this speed is +> still very very slow (a SQL command takes more than 2 seconds). It is a +> small table. There are only 8 records in the table. +> +> The only way to solve it is remove all database, run initdb, create new +> database and insert new records. I tried to run vacummdb but still very +> slow. +> +> Any idea to make it faster? +> +> Thanks, +> Alex +> +> -- +> Here is the table schema: +> create table download_queue ( +> task_id SERIAL, +> username varchar(128), +> pid int, +> url text, +> filename varchar(1024), +> status int, +> created_time int, +> started_time int, +> total_size int8, +> current_size int8, +> current_rate int, +> CONSTRAINT download_queue_pkey PRIMARY KEY(task_id) +> ); +> CREATE INDEX download_queue_user_index ON download_queue USING BTREE +> (username); +> +> + + +From pgsql-performance-owner@postgresql.org Sat Nov 19 08:05:32 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 2256FDBBC3 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 08:05:30 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 12555-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 12:05:31 +0000 (GMT) +X-Greylist: delayed 04:19:02.469402 by SQLgrey- +Received: from alexwang.com (alexwang.com [220.132.178.72]) + by svr1.postgresql.org (Postfix) with ESMTP id 0DFB0DBBEE + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 08:05:26 -0400 (AST) +Received: from alexxp ([192.168.0.2]) (authenticated bits=0) + by alexwang.com (8.13.5/8.13.5) with ESMTP id jAJC5nio018695; + Sat, 19 Nov 2005 20:05:50 +0800 (CST) +Message-ID: <005201c5ed01$7f15c310$0200a8c0@alexxp> +From: "Alex Wang" <alex@alexwang.com> +To: "Csaba Nagy" <nagy@ecircle-ag.com> +Cc: "postgres performance list" <pgsql-performance@postgresql.org> +References: <002601c5ecdd$503279e0$0200a8c0@alexxp> + <1132398732.10890.480.camel@coppola.muc.ecircle.de> +Subject: Re: VERY slow after many updates +Date: Sat, 19 Nov 2005 20:05:00 +0800 +MIME-Version: 1.0 +Content-Type: text/plain; format=flowed; charset="big5"; reply-type=original +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2900.2527 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2527 +X-twbsd-MailScanner-Information: Please contact the ISP for more information +X-twbsd-MailScanner: Found to be clean +X-twbsd-MailScanner-From: alex@alexwang.com +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.932 required=5 tests=[AWL=-1.932, + RCVD_IN_NJABL_DUL=1.713, RCVD_IN_WHOIS_INVALID=2.151] +X-Spam-Score: 1.932 +X-Spam-Level: * +X-Archive-Number: 200511/394 +X-Sequence-Number: 15651 + +Hi Csaba, + +Thanks for your reply. + +Yes, it's a "queue" table. But I did not perform many insert/delete before +it becomes slow. After insert 10 records, I just do get/update continuously. +After 24 hour, the whole database become very slow (not only the +download_queue table but other tables, too). But you are right. Full vacuum +fixes the problem. Thank you very much! + +I expect there will be less than 1000 records in the table. The index does +obvous improvement on "SELECT task_id, username FROM download_queue WHERE +username > '%s'" even there are only 100 records. + +Thanks, +Alex + +----- Original Message ----- +From: "Csaba Nagy" <nagy@ecircle-ag.com> +To: "Alex Wang" <alex@alexwang.com> +Cc: "postgres performance list" <pgsql-performance@postgresql.org> +Sent: Saturday, November 19, 2005 7:12 PM +Subject: Re: [PERFORM] VERY slow after many updates + + +> Alex, +> +> I suppose the table is a kind of 'queue' table, where you +> insert/get/delete continuously, and the life of the records is short. +> Considering that in postgres a delete will still leave you the record in +> the table's file and in the indexes, just mark it as dead, your table's +> actual size can grow quite a lot even if the number of live records will +> stay small (you will have a lot of dead tuples, the more tasks +> processed, the more dead tuples). So I guess you should vacuum this +> table very often, so that the dead tuples are reused. I'm not an expert +> on this, but it might be good to vacuum after each n deletions, where n +> is ~ half the average size of the queue you expect to have. From time to +> time you might want to do a vacuum full on it and a reindex. +> +> Right now I guess a vacuum full + reindex will help you. I think it's +> best to do: +> +> vacuum download_queue; +> vacuum full download_queue; +> reindex download_queue; +> +> I think the non-full vacuum which is less obtrusive than the full one +> will do at least some of the work and it will bring all needed things in +> FS cache, so the full vacuum to be as fast as possible (vacuum full +> locks exclusively the table). At least I do it this way with good +> results for small queue-like tables... +> +> BTW, I wonder if the download_queue_user_index index is helping you at +> all on that table ? Do you expect it to grow bigger than 1000 ? +> Otherwise it has no point to index it. +> +> HTH, +> Csaba. +> +> On Sat, 2005-11-19 at 08:46, Alex Wang wrote: +>> I am using PostgreSQL in an embedded system which has only 32 or 64 MB +>> RAM +>> (run on PPC 266 MHz or ARM 266MHz CPU). I have a table to keep downlaod +>> tasks. There is a daemon keep looking up the table and fork a new process +>> to +>> download data from internet. +>> +>> Daemon: +>> . Check the table every 5 seconds +>> . Fork a download process to download if there is new task +>> Downlaod process (there are 5 download process max): +>> . Update the download rate and downloaded size every 3 seconds. +>> +>> At begining, everything just fine. The speed is good. But after 24 hours, +>> the speed to access database become very very slow. Even I stop all +>> processes, restart PostgreSQL and use psql to select data, this speed is +>> still very very slow (a SQL command takes more than 2 seconds). It is a +>> small table. There are only 8 records in the table. +>> +>> The only way to solve it is remove all database, run initdb, create new +>> database and insert new records. I tried to run vacummdb but still very +>> slow. +>> +>> Any idea to make it faster? +>> +>> Thanks, +>> Alex +>> +>> -- +>> Here is the table schema: +>> create table download_queue ( +>> task_id SERIAL, +>> username varchar(128), +>> pid int, +>> url text, +>> filename varchar(1024), +>> status int, +>> created_time int, +>> started_time int, +>> total_size int8, +>> current_size int8, +>> current_rate int, +>> CONSTRAINT download_queue_pkey PRIMARY KEY(task_id) +>> ); +>> CREATE INDEX download_queue_user_index ON download_queue USING BTREE +>> (username); +>> +>> +> +> +> -- +> This message has been scanned for viruses and +> dangerous content by MailScanner, and is +> believed to be clean. +> + + +-- +This message has been scanned for viruses and +dangerous content by MailScanner, and is +believed to be clean. + + +From pgsql-performance-owner@postgresql.org Sat Nov 19 08:12:55 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 95232DBC08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 08:12:53 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14318-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 12:12:55 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.ecircle.de (mail.ecircle.de [195.140.186.200]) + by svr1.postgresql.org (Postfix) with ESMTP id 593E9DBBBE + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 08:12:49 -0400 (AST) +Received: from [192.168.1.110] (unknown [192.168.1.110]) + by mail.ecircle.de (READY) with ESMTP id 945C19541ED; + Sat, 19 Nov 2005 13:12:52 +0100 (CET) +Subject: Re: VERY slow after many updates +From: Csaba Nagy <nagy@ecircle-ag.com> +To: Alex Wang <alex@alexwang.com> +Cc: postgres performance list <pgsql-performance@postgresql.org> +In-Reply-To: <005201c5ed01$7f15c310$0200a8c0@alexxp> +References: <002601c5ecdd$503279e0$0200a8c0@alexxp> + <1132398732.10890.480.camel@coppola.muc.ecircle.de> + <005201c5ed01$7f15c310$0200a8c0@alexxp> +Content-Type: text/plain +Message-Id: <1132402372.10890.487.camel@coppola.muc.ecircle.de> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) +Date: Sat, 19 Nov 2005 13:12:52 +0100 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/395 +X-Sequence-Number: 15652 + +Just for clarification, update is actually equal to delete+insert in +Postgres. So if you update rows, it's the same as you would delete the +row and insert a new version. So the table is bloating also in this +situation. +I think there is an added problem when you update, namely to get to a +row, postgres will traverse all dead rows matching the criteria... so +even if you have an index, getting 1 row which was updated 10000 times +will access 10000 rows only to find 1 which is still alive. So in this +case vacuuming should happen even more often, to eliminate the dead +rows. +And the index was probably only helping because the table was really +bloated, so if you vacuum it often enough you will be better off without +the index if the row count will stay low. + +Cheers, +Csaba. + + +On Sat, 2005-11-19 at 13:05, Alex Wang wrote: +> Hi Csaba, +> +> Thanks for your reply. +> +> Yes, it's a "queue" table. But I did not perform many insert/delete before +> it becomes slow. After insert 10 records, I just do get/update continuously. +> After 24 hour, the whole database become very slow (not only the +> download_queue table but other tables, too). But you are right. Full vacuum +> fixes the problem. Thank you very much! +> +> I expect there will be less than 1000 records in the table. The index does +> obvous improvement on "SELECT task_id, username FROM download_queue WHERE +> username > '%s'" even there are only 100 records. +> +> Thanks, +> Alex +> +> ----- Original Message ----- +> From: "Csaba Nagy" <nagy@ecircle-ag.com> +> To: "Alex Wang" <alex@alexwang.com> +> Cc: "postgres performance list" <pgsql-performance@postgresql.org> +> Sent: Saturday, November 19, 2005 7:12 PM +> Subject: Re: [PERFORM] VERY slow after many updates +> +> +> > Alex, +> > +> > I suppose the table is a kind of 'queue' table, where you +> > insert/get/delete continuously, and the life of the records is short. +> > Considering that in postgres a delete will still leave you the record in +> > the table's file and in the indexes, just mark it as dead, your table's +> > actual size can grow quite a lot even if the number of live records will +> > stay small (you will have a lot of dead tuples, the more tasks +> > processed, the more dead tuples). So I guess you should vacuum this +> > table very often, so that the dead tuples are reused. I'm not an expert +> > on this, but it might be good to vacuum after each n deletions, where n +> > is ~ half the average size of the queue you expect to have. From time to +> > time you might want to do a vacuum full on it and a reindex. +> > +> > Right now I guess a vacuum full + reindex will help you. I think it's +> > best to do: +> > +> > vacuum download_queue; +> > vacuum full download_queue; +> > reindex download_queue; +> > +> > I think the non-full vacuum which is less obtrusive than the full one +> > will do at least some of the work and it will bring all needed things in +> > FS cache, so the full vacuum to be as fast as possible (vacuum full +> > locks exclusively the table). At least I do it this way with good +> > results for small queue-like tables... +> > +> > BTW, I wonder if the download_queue_user_index index is helping you at +> > all on that table ? Do you expect it to grow bigger than 1000 ? +> > Otherwise it has no point to index it. +> > +> > HTH, +> > Csaba. +> > +> > On Sat, 2005-11-19 at 08:46, Alex Wang wrote: +> >> I am using PostgreSQL in an embedded system which has only 32 or 64 MB +> >> RAM +> >> (run on PPC 266 MHz or ARM 266MHz CPU). I have a table to keep downlaod +> >> tasks. There is a daemon keep looking up the table and fork a new process +> >> to +> >> download data from internet. +> >> +> >> Daemon: +> >> . Check the table every 5 seconds +> >> . Fork a download process to download if there is new task +> >> Downlaod process (there are 5 download process max): +> >> . Update the download rate and downloaded size every 3 seconds. +> >> +> >> At begining, everything just fine. The speed is good. But after 24 hours, +> >> the speed to access database become very very slow. Even I stop all +> >> processes, restart PostgreSQL and use psql to select data, this speed is +> >> still very very slow (a SQL command takes more than 2 seconds). It is a +> >> small table. There are only 8 records in the table. +> >> +> >> The only way to solve it is remove all database, run initdb, create new +> >> database and insert new records. I tried to run vacummdb but still very +> >> slow. +> >> +> >> Any idea to make it faster? +> >> +> >> Thanks, +> >> Alex +> >> +> >> -- +> >> Here is the table schema: +> >> create table download_queue ( +> >> task_id SERIAL, +> >> username varchar(128), +> >> pid int, +> >> url text, +> >> filename varchar(1024), +> >> status int, +> >> created_time int, +> >> started_time int, +> >> total_size int8, +> >> current_size int8, +> >> current_rate int, +> >> CONSTRAINT download_queue_pkey PRIMARY KEY(task_id) +> >> ); +> >> CREATE INDEX download_queue_user_index ON download_queue USING BTREE +> >> (username); +> >> +> >> +> > +> > +> > -- +> > This message has been scanned for viruses and +> > dangerous content by MailScanner, and is +> > believed to be clean. +> > +> + + +From pgsql-performance-owner@postgresql.org Sat Nov 19 08:18:29 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 05FFCDBC0F + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 08:18:28 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14318-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 12:18:26 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from pharmaline.de (mail.pharmaline.de [62.153.135.34]) + by svr1.postgresql.org (Postfix) with ESMTP id 4EDBADBC09 + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 08:18:19 -0400 (AST) +Received: from [192.168.0.5] (84.60.170.103) by pharmaline.de with ESMTP + (Eudora Internet Mail Server 3.2.6); Sat, 19 Nov 2005 12:18:24 +0100 +In-Reply-To: <005201c5ed01$7f15c310$0200a8c0@alexxp> +References: <002601c5ecdd$503279e0$0200a8c0@alexxp> + <1132398732.10890.480.camel@coppola.muc.ecircle.de> + <005201c5ed01$7f15c310$0200a8c0@alexxp> +Mime-Version: 1.0 (Apple Message framework v746.2) +X-Priority: 3 +Content-Type: multipart/signed; micalg=sha1; boundary=Apple-Mail-6--523322015; + protocol="application/pkcs7-signature" +Message-Id: <AC098147-E4DC-4313-AFB3-196F1B81B96E@pharmaline.de> +Cc: Alex Wang <alex@alexwang.com> +From: Guido Neitzer <guido.neitzer@pharmaline.de> +Subject: Re: VERY slow after many updates +Date: Sat, 19 Nov 2005 13:18:19 +0100 +To: postgres performance list <pgsql-performance@postgresql.org> +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.236 required=5 tests=[RCVD_IN_SORBS_WEB=1.236] +X-Spam-Score: 1.236 +X-Spam-Level: * +X-Archive-Number: 200511/396 +X-Sequence-Number: 15653 + + +--Apple-Mail-6--523322015 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; + charset=US-ASCII; + delsp=yes; + format=flowed + +On 19.11.2005, at 13:05 Uhr, Alex Wang wrote: + +> Yes, it's a "queue" table. But I did not perform many insert/delete +> before it becomes slow. After insert 10 records, I just do get/ +> update continuously. + +When PostgreSQL updates a row, it creates a new row with the updated +values. So you should be aware, that the DB gets bigger and bigger +when you only update your rows. Vacuum full reclaims that used space. + +The concepts are described in detail in the manual in chapter 12. + +cug + +-- +PharmaLine Essen, GERMANY and +Big Nerd Ranch Europe - PostgreSQL Training, Dec. 2005, Rome, Italy +http://www.bignerdranch.com/classes/postgresql.shtml + + + +--Apple-Mail-6--523322015 +Content-Transfer-Encoding: base64 +Content-Type: application/pkcs7-signature; + name=smime.p7s +Content-Disposition: attachment; + filename=smime.p7s + +MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIGUzCCAwww +ggJ1oAMCAQICAw4DazANBgkqhkiG9w0BAQQFADBiMQswCQYDVQQGEwJaQTElMCMGA1UEChMcVGhh +d3RlIENvbnN1bHRpbmcgKFB0eSkgTHRkLjEsMCoGA1UEAxMjVGhhd3RlIFBlcnNvbmFsIEZyZWVt +YWlsIElzc3VpbmcgQ0EwHhcNMDUwMjExMDkwNzMwWhcNMDYwMjExMDkwNzMwWjBpMR8wHQYDVQQD +ExZUaGF3dGUgRnJlZW1haWwgTWVtYmVyMSowKAYJKoZIhvcNAQkBFhtndWlkby5uZWl0emVyQHBo +YXJtYWxpbmUuZGUxGjAYBgkqhkiG9w0BCQEWC2N1Z0BtYWMuY29tMIIBIjANBgkqhkiG9w0BAQEF +AAOCAQ8AMIIBCgKCAQEA5/WRLVRqtqJ+f/HOn9G513YNybt/lglgrEjo281eSXV0O1boJcCA7FuA +B+Wc7BiltSkLc4nvJSegJh0RydSOKt3MywBg+N8BkgxcSWf9jYJ/JUx4uTBWAdd4Hk1+XPGHpYzQ +Ric2AofRqhW8IQX/unprQ/BnAMiiuukaaGB8dqtoXDBI0RYlwHYuOTyrviEdU7jt4kgrBYu4TK01 +qqKsxkr2Q7WhNT9p9w7Fu8rZF+VuJPwbZPIsfWuPZbN/7HRKoaKLG04UG1CmiqiN9JQl4tR81G4k +8WkSTPy0JruJHfOm584a1JposZwtwmcOo1l5iDJtnzSB4PvdFnFYVkJ9IQIDAQABo0UwQzAzBgNV +HREELDAqgRtndWlkby5uZWl0emVyQHBoYXJtYWxpbmUuZGWBC2N1Z0BtYWMuY29tMAwGA1UdEwEB +/wQCMAAwDQYJKoZIhvcNAQEEBQADgYEAgg9T+k6d3YQITWeSYwDSPTAGN0z/BMVhrOlzF7cP4srd +jU4L0RLiqFMz9D2tCMFV5P0z1FIxjSqXBpt7xkzSE8sYplMUMLBRMIV4sJbPAbdqGiB+MGLSzh7V +N95dP7LwrRjFqury6j0RQ3OG6oqStCpfcMmWuAHT7gRNwjeAaQYwggM/MIICqKADAgECAgENMA0G +CSqGSIb3DQEBBQUAMIHRMQswCQYDVQQGEwJaQTEVMBMGA1UECBMMV2VzdGVybiBDYXBlMRIwEAYD +VQQHEwlDYXBlIFRvd24xGjAYBgNVBAoTEVRoYXd0ZSBDb25zdWx0aW5nMSgwJgYDVQQLEx9DZXJ0 +aWZpY2F0aW9uIFNlcnZpY2VzIERpdmlzaW9uMSQwIgYDVQQDExtUaGF3dGUgUGVyc29uYWwgRnJl +ZW1haWwgQ0ExKzApBgkqhkiG9w0BCQEWHHBlcnNvbmFsLWZyZWVtYWlsQHRoYXd0ZS5jb20wHhcN +MDMwNzE3MDAwMDAwWhcNMTMwNzE2MjM1OTU5WjBiMQswCQYDVQQGEwJaQTElMCMGA1UEChMcVGhh +d3RlIENvbnN1bHRpbmcgKFB0eSkgTHRkLjEsMCoGA1UEAxMjVGhhd3RlIFBlcnNvbmFsIEZyZWVt +YWlsIElzc3VpbmcgQ0EwgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJAoGBAMSmPFVzVftOucqZWh5o +wHUEcJ3f6f+jHuy9zfVb8hp2vX8MOmHyv1HOAdTlUAow1wJjWiyJFXCO3cnwK4Vaqj9xVsuvPAsH +5/EfkTYkKhPPK9Xzgnc9A74r/rsYPge/QIACZNenprufZdHFKlSFD0gEf6e20TxhBEAeZBlyYLf7 +AgMBAAGjgZQwgZEwEgYDVR0TAQH/BAgwBgEB/wIBADBDBgNVHR8EPDA6MDigNqA0hjJodHRwOi8v +Y3JsLnRoYXd0ZS5jb20vVGhhd3RlUGVyc29uYWxGcmVlbWFpbENBLmNybDALBgNVHQ8EBAMCAQYw +KQYDVR0RBCIwIKQeMBwxGjAYBgNVBAMTEVByaXZhdGVMYWJlbDItMTM4MA0GCSqGSIb3DQEBBQUA +A4GBAEiM0VCD6gsuzA2jZqxnD3+vrL7CF6FDlpSdf0whuPg2H6otnzYvwPQcUCCTcDz9reFhYsPZ +Ohl+hLGZGwDFGguCdJ4lUJRix9sncVcljd2pnDmOjCBPZV+V2vf3h9bGCE6u9uo05RAaWzVNd+NW +IXiC3CEZNd4ksdMdRv9dX2VPMYIC5zCCAuMCAQEwaTBiMQswCQYDVQQGEwJaQTElMCMGA1UEChMc +VGhhd3RlIENvbnN1bHRpbmcgKFB0eSkgTHRkLjEsMCoGA1UEAxMjVGhhd3RlIFBlcnNvbmFsIEZy +ZWVtYWlsIElzc3VpbmcgQ0ECAw4DazAJBgUrDgMCGgUAoIIBUzAYBgkqhkiG9w0BCQMxCwYJKoZI +hvcNAQcBMBwGCSqGSIb3DQEJBTEPFw0wNTExMTkxMjE4MjBaMCMGCSqGSIb3DQEJBDEWBBQ8SPYd +PS5AeeZG8RNRFodt7MYSujB4BgkrBgEEAYI3EAQxazBpMGIxCzAJBgNVBAYTAlpBMSUwIwYDVQQK +ExxUaGF3dGUgQ29uc3VsdGluZyAoUHR5KSBMdGQuMSwwKgYDVQQDEyNUaGF3dGUgUGVyc29uYWwg +RnJlZW1haWwgSXNzdWluZyBDQQIDDgNrMHoGCyqGSIb3DQEJEAILMWugaTBiMQswCQYDVQQGEwJa +QTElMCMGA1UEChMcVGhhd3RlIENvbnN1bHRpbmcgKFB0eSkgTHRkLjEsMCoGA1UEAxMjVGhhd3Rl +IFBlcnNvbmFsIEZyZWVtYWlsIElzc3VpbmcgQ0ECAw4DazANBgkqhkiG9w0BAQEFAASCAQApEWmc +hGbhvBJ9xFRmxrOgGpn5P5AS+48DtP6reJrg588JSF/hbC3LKqDwecATC/rsdpQYq0aBA/jPShox +e5UmBsTf9+O/bu0PzwaAXDjrokp6XVXhky+U6DdWvqRa0i1lr9f6kSHCXYr9w1oyi5KnSH7JHTm2 +1qceY8YFhX4QqgqxcoAew5QvEgWR+eGiglsixVfqkv4Y4kbwUoVbLnTI1lP8AjeVjKErnSr8QM0G +K1Gvj340+p7w36A9RziZEFaoRjVMS1YaW8V10MX9MmqhbnR7mVN54W90jTq4fTrzJYVd/h/PRj5k +MjDwLSTb4OQIWvhi+61L4gKOk4yqDc6yAAAAAAAA + +--Apple-Mail-6--523322015-- + +From pgsql-performance-owner@postgresql.org Sat Nov 19 08:30:23 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 7389DDBB80 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 08:30:22 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 13970-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 12:30:24 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from alexwang.com (alexwang.com [220.132.178.72]) + by svr1.postgresql.org (Postfix) with ESMTP id 03C7ADBC17 + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 08:30:18 -0400 (AST) +Received: from alexxp ([192.168.0.2]) (authenticated bits=0) + by alexwang.com (8.13.5/8.13.5) with ESMTP id jAJCUX2x018898; + Sat, 19 Nov 2005 20:30:38 +0800 (CST) +Message-ID: <006b01c5ed04$f640ef70$0200a8c0@alexxp> +From: "Alex Wang" <alex@alexwang.com> +To: "Csaba Nagy" <nagy@ecircle-ag.com> +Cc: "postgres performance list" <pgsql-performance@postgresql.org> +References: <002601c5ecdd$503279e0$0200a8c0@alexxp> + <1132398732.10890.480.camel@coppola.muc.ecircle.de> + <005201c5ed01$7f15c310$0200a8c0@alexxp> + <1132402372.10890.487.camel@coppola.muc.ecircle.de> +Subject: Re: VERY slow after many updates +Date: Sat, 19 Nov 2005 20:29:47 +0800 +MIME-Version: 1.0 +Content-Type: text/plain; format=flowed; charset="big5"; reply-type=original +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2900.2527 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2527 +X-twbsd-MailScanner-Information: Please contact the ISP for more information +X-twbsd-MailScanner: Found to be clean +X-twbsd-MailScanner-From: alex@alexwang.com +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=2.415 required=5 tests=[AWL=-1.449, + RCVD_IN_NJABL_DUL=1.713, RCVD_IN_WHOIS_INVALID=2.151] +X-Spam-Score: 2.415 +X-Spam-Level: ** +X-Archive-Number: 200511/397 +X-Sequence-Number: 15654 + +Great infomation. I didn't know that update is equal to delete+insert in +Postgres. I would be more careful on designing the database access method in +this case. + +Thanks, +Alex + +----- Original Message ----- +From: "Csaba Nagy" <nagy@ecircle-ag.com> +To: "Alex Wang" <alex@alexwang.com> +Cc: "postgres performance list" <pgsql-performance@postgresql.org> +Sent: Saturday, November 19, 2005 8:12 PM +Subject: Re: [PERFORM] VERY slow after many updates + + +> Just for clarification, update is actually equal to delete+insert in +> Postgres. So if you update rows, it's the same as you would delete the +> row and insert a new version. So the table is bloating also in this +> situation. +> I think there is an added problem when you update, namely to get to a +> row, postgres will traverse all dead rows matching the criteria... so +> even if you have an index, getting 1 row which was updated 10000 times +> will access 10000 rows only to find 1 which is still alive. So in this +> case vacuuming should happen even more often, to eliminate the dead +> rows. +> And the index was probably only helping because the table was really +> bloated, so if you vacuum it often enough you will be better off without +> the index if the row count will stay low. +> +> Cheers, +> Csaba. +> +> +> On Sat, 2005-11-19 at 13:05, Alex Wang wrote: +>> Hi Csaba, +>> +>> Thanks for your reply. +>> +>> Yes, it's a "queue" table. But I did not perform many insert/delete +>> before +>> it becomes slow. After insert 10 records, I just do get/update +>> continuously. +>> After 24 hour, the whole database become very slow (not only the +>> download_queue table but other tables, too). But you are right. Full +>> vacuum +>> fixes the problem. Thank you very much! +>> +>> I expect there will be less than 1000 records in the table. The index +>> does +>> obvous improvement on "SELECT task_id, username FROM download_queue WHERE +>> username > '%s'" even there are only 100 records. +>> +>> Thanks, +>> Alex +>> +>> ----- Original Message ----- +>> From: "Csaba Nagy" <nagy@ecircle-ag.com> +>> To: "Alex Wang" <alex@alexwang.com> +>> Cc: "postgres performance list" <pgsql-performance@postgresql.org> +>> Sent: Saturday, November 19, 2005 7:12 PM +>> Subject: Re: [PERFORM] VERY slow after many updates +>> +>> +>> > Alex, +>> > +>> > I suppose the table is a kind of 'queue' table, where you +>> > insert/get/delete continuously, and the life of the records is short. +>> > Considering that in postgres a delete will still leave you the record +>> > in +>> > the table's file and in the indexes, just mark it as dead, your table's +>> > actual size can grow quite a lot even if the number of live records +>> > will +>> > stay small (you will have a lot of dead tuples, the more tasks +>> > processed, the more dead tuples). So I guess you should vacuum this +>> > table very often, so that the dead tuples are reused. I'm not an expert +>> > on this, but it might be good to vacuum after each n deletions, where n +>> > is ~ half the average size of the queue you expect to have. From time +>> > to +>> > time you might want to do a vacuum full on it and a reindex. +>> > +>> > Right now I guess a vacuum full + reindex will help you. I think it's +>> > best to do: +>> > +>> > vacuum download_queue; +>> > vacuum full download_queue; +>> > reindex download_queue; +>> > +>> > I think the non-full vacuum which is less obtrusive than the full one +>> > will do at least some of the work and it will bring all needed things +>> > in +>> > FS cache, so the full vacuum to be as fast as possible (vacuum full +>> > locks exclusively the table). At least I do it this way with good +>> > results for small queue-like tables... +>> > +>> > BTW, I wonder if the download_queue_user_index index is helping you at +>> > all on that table ? Do you expect it to grow bigger than 1000 ? +>> > Otherwise it has no point to index it. +>> > +>> > HTH, +>> > Csaba. +>> > +>> > On Sat, 2005-11-19 at 08:46, Alex Wang wrote: +>> >> I am using PostgreSQL in an embedded system which has only 32 or 64 MB +>> >> RAM +>> >> (run on PPC 266 MHz or ARM 266MHz CPU). I have a table to keep +>> >> downlaod +>> >> tasks. There is a daemon keep looking up the table and fork a new +>> >> process +>> >> to +>> >> download data from internet. +>> >> +>> >> Daemon: +>> >> . Check the table every 5 seconds +>> >> . Fork a download process to download if there is new task +>> >> Downlaod process (there are 5 download process max): +>> >> . Update the download rate and downloaded size every 3 seconds. +>> >> +>> >> At begining, everything just fine. The speed is good. But after 24 +>> >> hours, +>> >> the speed to access database become very very slow. Even I stop all +>> >> processes, restart PostgreSQL and use psql to select data, this speed +>> >> is +>> >> still very very slow (a SQL command takes more than 2 seconds). It is +>> >> a +>> >> small table. There are only 8 records in the table. +>> >> +>> >> The only way to solve it is remove all database, run initdb, create +>> >> new +>> >> database and insert new records. I tried to run vacummdb but still +>> >> very +>> >> slow. +>> >> +>> >> Any idea to make it faster? +>> >> +>> >> Thanks, +>> >> Alex +>> >> +>> >> -- +>> >> Here is the table schema: +>> >> create table download_queue ( +>> >> task_id SERIAL, +>> >> username varchar(128), +>> >> pid int, +>> >> url text, +>> >> filename varchar(1024), +>> >> status int, +>> >> created_time int, +>> >> started_time int, +>> >> total_size int8, +>> >> current_size int8, +>> >> current_rate int, +>> >> CONSTRAINT download_queue_pkey PRIMARY KEY(task_id) +>> >> ); +>> >> CREATE INDEX download_queue_user_index ON download_queue USING BTREE +>> >> (username); +>> >> +>> >> +>> > +>> > +>> > -- +>> > This message has been scanned for viruses and +>> > dangerous content by MailScanner, and is +>> > believed to be clean. +>> > +>> +> +> +> -- +> This message has been scanned for viruses and +> dangerous content by MailScanner, and is +> believed to be clean. +> + + +-- +This message has been scanned for viruses and +dangerous content by MailScanner, and is +believed to be clean. + + +From pgsql-performance-owner@postgresql.org Sat Nov 19 09:45:09 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 397ADDBC24 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 09:45:09 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 27656-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 13:45:11 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id A1BEEDB7FA + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 09:45:06 -0400 (AST) +Received: from worleyco.com (unknown [70.158.54.226]) + by svr2.postgresql.org (Postfix) with ESMTP id 7D97CF0B2C + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 13:45:10 +0000 (GMT) +Received: from [192.168.4.32] (unknown [192.168.4.32]) + by worleyco.com (Postfix) with ESMTP id 73B5E12E718 + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 07:45:09 -0600 (CST) +Message-ID: <437F2C66.3030603@hardgeus.com> +Date: Sat, 19 Nov 2005 07:45:10 -0600 +From: John McCawley <nospam@hardgeus.com> +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20050716) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: What is the max number of database I can create in +References: <BAY106-F29AAEBFDCAA6E044ECFAC6B7510@phx.gbl> + <EEBF2C76-224F-4AB4-985E-2525A5DAA2EF@myrealbox.com> +In-Reply-To: <EEBF2C76-224F-4AB4-985E-2525A5DAA2EF@myrealbox.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/398 +X-Sequence-Number: 15655 + + +>> However, what is the max number of database I can create before +>> performance goes down? +> +I know I'm not directly answering your question, but you might want to +consider why you're splitting things up into different logical +databases. If security is a big concern, you can create different +database users that own the different departments' tables, and each of +your apps can login as the corresponding users. + +Everyone loves reports. Once you've got data in your database, people +will ask for a billion reports...Whether or not they know it now, most +likely they're going to want reports that cross the department +boundaries (gross revenue, employee listings etc.) and that will be very +difficult if you have multiple databases. + + + +From pgsql-performance-owner@postgresql.org Sat Nov 19 12:13:32 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 63F68DBC43 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 12:13:31 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 40790-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 16:13:29 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw02.mi8.com [63.240.6.46]) + by svr1.postgresql.org (Postfix) with ESMTP id 5748ADBC19 + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 12:13:27 -0400 (AST) +Received: from 172.16.1.112 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D2)); Sat, 19 Nov 2005 11:13:10 -0500 +X-Server-Uuid: 7829E76E-BB9E-4995-8473-3C0929DF7DD1 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Sat, 19 Nov + 2005 11:13:10 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Sat, 19 Nov + 2005 11:13:10 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Sat, 19 Nov 2005 08:13:09 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: stange@rentec.com, + "Greg Stark" <gsstark@mit.edu> +cc: "Dave Cramer" <pg@fastcrypt.com>, "Joshua Marsh" <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Message-ID: <BFA48F15.14182%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXseIujtrf4zfrUS8uGzWRjlVpIrQAq5YQU +In-Reply-To: <437E2DF2.50906@rentec.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 19 Nov 2005 16:13:10.0720 (UTC) + FILETIME=[22BACC00:01C5ED24] +X-WSS-ID: 6F61909C2RS10459626-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.253 required=5 tests=[AWL=0.000, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.253 +X-Spam-Level: * +X-Archive-Number: 200511/399 +X-Sequence-Number: 15656 + +Alan, + +On 11/18/05 11:39 AM, "Alan Stange" <stange@rentec.com> wrote: + +> Yes and no. The one cpu is clearly idle. The second cpu is 40% busy +> and 60% idle (aka iowait in the above numbers). + +The "aka iowait" is the problem here - iowait is not idle (otherwise it +would be in the "idle" column). + +Iowait is time spent waiting on blocking io calls. As another poster +pointed out, you have a two CPU system, and during your scan, as predicted, +one CPU went 100% busy on the seq scan. During iowait periods, the CPU can +be context switched to other users, but as I pointed out earlier, that's not +useful for getting response on decision support queries. + +Thanks for your data, it exemplifies many of the points brought up: +- Lots of disks and expensive I/O hardware does not help improve performance +on large table queries because I/O bandwidth does not scale beyond +110-120MB/s on the fastest CPUs +- OLTP performance optimizations are different than decision support + +Regards, + +- Luke + + + +From pgsql-performance-owner@postgresql.org Sat Nov 19 12:15:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 102E6DBBA2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 12:15:45 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 37611-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 16:15:43 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id 4B92ADBB96 + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 12:15:42 -0400 (AST) +Received: from 172.16.1.112 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Sat, 19 Nov 2005 11:15:31 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Sat, 19 Nov + 2005 11:15:31 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Sat, 19 Nov + 2005 11:15:30 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Sat, 19 Nov 2005 08:15:29 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Mark Kirkwood" <markir@paradise.net.nz> +cc: "Dave Cramer" <pg@fastcrypt.com>, "Greg Stark" <gsstark@mit.edu>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-ID: <BFA48FA1.14183%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXssN0ZViVaQXB4RgWzT+CnPb8m7gAc5gMJ +In-Reply-To: <437E8DA5.1050703@paradise.net.nz> +MIME-Version: 1.0 +X-OriginalArrivalTime: 19 Nov 2005 16:15:31.0170 (UTC) + FILETIME=[7671C420:01C5ED24] +X-WSS-ID: 6F61902931S15625257-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.253 required=5 tests=[AWL=0.000, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.253 +X-Spam-Level: * +X-Archive-Number: 200511/400 +X-Sequence-Number: 15657 + +Mark, + +On 11/18/05 6:27 PM, "Mark Kirkwood" <markir@paradise.net.nz> wrote: + +> That too, meaning the business of 1 executor random reading a given +> relation file whilst another is sequentially scanning (some other) part +> of it.... + +I think it should actually improve things - each I/O will read 16MB into the +I/O cache, then the next scanner will seek for 10ms to get the next 16MB +into cache, etc. It should minimize the seek/data ratio nicely. As long as +the tables are contiguous it should rock and roll. + +- Luke + + + +From pgsql-performance-owner@postgresql.org Sat Nov 19 13:57:10 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 77A92DBC53 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 13:57:09 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 48748-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 17:57:08 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 09D06DBC69 + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 13:57:06 -0400 (AST) +Received: from moonunit2.moonview.localnet (wsip-68-15-5-150.sd.sd.cox.net + [68.15.5.150]) + by svr2.postgresql.org (Postfix) with ESMTP id F3BEBF0B09 + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 17:57:06 +0000 (GMT) +Received: from [192.168.0.3] (moonunit3.moonview.localnet [192.168.0.3]) + by moonunit2.moonview.localnet (8.13.1/8.13.1) with ESMTP id + jAJI5gOJ002071 + for <pgsql-performance@postgresql.org>; Sat, 19 Nov 2005 10:05:42 -0800 +Message-ID: <437F66CF.7080402@modgraph-usa.com> +Date: Sat, 19 Nov 2005 09:54:23 -0800 +From: "Craig A. James" <cjames@modgraph-usa.com> +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20050716) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Storage/Performance and splitting a table +References: <BF9F6C0E.13B4A%llonergan@greenplum.com> + <1132136225.5711.4.camel@Panoramix> + <437B9DA9.2030806@modgraph-usa.com> + <20051117002344.GA55377@winnie.fuhr.org> + <437CF055.6020602@modgraph-usa.com> + <20051117232857.GA49910@winnie.fuhr.org> + <437D3085.9040207@modgraph-usa.com> + <20051118034631.GA70159@winnie.fuhr.org> +In-Reply-To: <20051118034631.GA70159@winnie.fuhr.org> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.047 required=5 tests=[AWL=0.047] +X-Spam-Score: 0.047 +X-Spam-Level: +X-Archive-Number: 200511/401 +X-Sequence-Number: 15658 + +In a recent thread, several people pointed out that UPDATE = DELETE+INSERT. This got me to wondering. + +I have a table that, roughly, looks like this: + + create table doc ( + id integer primary key, + document text, + keywords tsvector + ); + +where "keywords" has a GIST index. There are about 10 million rows in the table, and an average of 20 keywords per document. I have two questions. + +First, I occasionally rebuild the keywords, after which the VACUUM FULL ANALYZE takes a LONG time - like 24 hours. Given the UPDATE = DELETE+INSERT, it sounds like I'd be better off with something like this: + + create table doc ( + id integer primary key, + document text, + ); + create table keywords ( + id integer primary key, + keywords tsvector + ); + +Then I could just drop the GIST index, truncate the keywords table, rebuild the keywords, and reindex. My suspicion is that VACUUM FULL ANALYZE would be quick -- there would be no garbage to collect, so all it would to do is the ANALYZE part. + +My second question: With the doc and keywords split into two tables, would the tsearch2/GIST performance be faster? The second schema's "keywords" table has just pure keywords (no documents); does that translate to fewer blocks being read during a tsearch2/GIST query? Or are the "document" and "keywords" columns of the first schema already stored separately on disk so that the size of the "document" data doesn't affect the "keywords" search performance? + +Thanks, +Craig + +From pgsql-performance-owner@postgresql.org Sat Nov 19 15:03:10 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CBB1FDBB64 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 15:03:08 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 75019-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 19:03:08 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from vms042pub.verizon.net (vms042pub.verizon.net [206.46.252.42]) + by svr1.postgresql.org (Postfix) with ESMTP id 43AFFDBB5E + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 15:03:05 -0400 (AST) +Received: from osgiliath.mathom.us ([68.239.91.220]) + by vms042.mailsrvcs.net (Sun Java System Messaging Server 6.2-4.02 + (built Sep + 9 2005)) with ESMTPA id <0IQ700B15U94XYC8@vms042.mailsrvcs.net> for + pgsql-performance@postgresql.org; Sat, 19 Nov 2005 13:03:05 -0600 (CST) +Received: from localhost (localhost [127.0.0.1]) + by osgiliath.mathom.us (Postfix) with ESMTP id 4385460F531 for + <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 14:03:05 -0500 (EST) +Received: from osgiliath.mathom.us ([127.0.0.1]) + by localhost (osgiliath [127.0.0.1]) (amavisd-new, port 10024) + with LMTP id 28339-05-3 for <pgsql-performance@postgresql.org>; Sat, + 19 Nov 2005 14:03:05 -0500 (EST) +Received: by osgiliath.mathom.us (Postfix, from userid 1000) + id 209DF600635; Sat, 19 Nov 2005 14:03:05 -0500 (EST) +Date: Sat, 19 Nov 2005 14:03:04 -0500 +From: Michael Stone <mstone+postgres@mathom.us> +Subject: Re: Storage/Performance and splitting a table +In-reply-to: <437F66CF.7080402@modgraph-usa.com> +To: pgsql-performance@postgresql.org +Mail-followup-to: pgsql-performance@postgresql.org +Message-id: <20051119190304.GJ7330@mathom.us> +MIME-version: 1.0 +Content-type: text/plain; charset=us-ascii; format=flowed +Content-disposition: inline +X-Pgp-Fingerprint: 53 FF 38 00 E7 DD 0A 9C 84 52 84 C5 EE DF 7C 88 +X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at mathom.us +References: <BF9F6C0E.13B4A%llonergan@greenplum.com> + <1132136225.5711.4.camel@Panoramix> <437B9DA9.2030806@modgraph-usa.com> + <20051117002344.GA55377@winnie.fuhr.org> + <437CF055.6020602@modgraph-usa.com> + <20051117232857.GA49910@winnie.fuhr.org> + <437D3085.9040207@modgraph-usa.com> + <20051118034631.GA70159@winnie.fuhr.org> + <437F66CF.7080402@modgraph-usa.com> +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/402 +X-Sequence-Number: 15659 + +On Sat, Nov 19, 2005 at 09:54:23AM -0800, Craig A. James wrote: +>First, I occasionally rebuild the keywords, after which the VACUUM FULL +>ANALYZE takes a LONG time - like 24 hours. + +You know you just need vacuum, not vacuum full, right? + +Mike Stone + +From pgsql-performance-owner@postgresql.org Sat Nov 19 16:45:29 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 53A4CDBCA8 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 16:45:28 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 84851-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 20:45:28 +0000 (GMT) +X-Greylist: delayed 02:48:21.611924 by SQLgrey- +Received: from moonunit2.moonview.localnet (wsip-68-15-5-150.sd.sd.cox.net + [68.15.5.150]) + by svr1.postgresql.org (Postfix) with ESMTP id AC900DBCB5 + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 16:45:25 -0400 (AST) +Received: from [192.168.0.3] (moonunit3.moonview.localnet [192.168.0.3]) + by moonunit2.moonview.localnet (8.13.1/8.13.1) with ESMTP id + jAJKsAZs002212 + for <pgsql-performance@postgresql.org>; Sat, 19 Nov 2005 12:54:10 -0800 +Message-ID: <437F8E4A.8000603@modgraph-usa.com> +Date: Sat, 19 Nov 2005 12:42:50 -0800 +From: "Craig A. James" <cjames@modgraph-usa.com> +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20050716) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: Perl DBD and an alarming problem +References: <BF9F6C0E.13B4A%llonergan@greenplum.com> + <1132136225.5711.4.camel@Panoramix> + <437B9DA9.2030806@modgraph-usa.com> + <20051117002344.GA55377@winnie.fuhr.org> + <437CF055.6020602@modgraph-usa.com> + <20051117232857.GA49910@winnie.fuhr.org> + <437D3085.9040207@modgraph-usa.com> + <20051118034631.GA70159@winnie.fuhr.org> +In-Reply-To: <20051118034631.GA70159@winnie.fuhr.org> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.032 required=5 tests=[AWL=0.032] +X-Spam-Score: 0.032 +X-Spam-Level: +X-Archive-Number: 200511/403 +X-Sequence-Number: 15660 + + +>> When I set statement_timeout in the config file, it just didn't +>> do anything - it never timed out (PG 8.0.3). +> +>... but did you reload the server after you [changed statement_timeout]? + +Mystery solved. I have two servers; I was reconfiguring one and restarting the other. Duh. + +Thanks, +Craig + +From pgsql-performance-owner@postgresql.org Sat Nov 19 17:29:01 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9D8B2DBAA1 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 17:29:00 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14645-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 21:29:01 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from linda-2.paradise.net.nz (bm-2a.paradise.net.nz + [203.96.152.181]) + by svr1.postgresql.org (Postfix) with ESMTP id EF878DBA5F + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 17:28:57 -0400 (AST) +Received: from smtp-3.paradise.net.nz (tclsnelbe2-src-nat-1 [203.96.152.177]) + by linda-2.paradise.net.nz (Paradise.net.nz) + with ESMTP id <0IQ800EA810AX5@linda-2.paradise.net.nz> for + pgsql-performance@postgresql.org; Sun, 20 Nov 2005 10:28:58 +1300 (NZDT) +Received: from [192.168.1.11] (218-101-29-89.dsl.clear.net.nz [218.101.29.89]) + by smtp-3.paradise.net.nz (Postfix) with ESMTP id E46A51222A64; Sun, + 20 Nov 2005 10:28:57 +1300 (NZDT) +Date: Sun, 20 Nov 2005 10:28:57 +1300 +From: Mark Kirkwood <markir@paradise.net.nz> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <BFA3ABF0.14124%llonergan@greenplum.com> +To: Luke Lonergan <llonergan@greenplum.com> +Cc: Dave Cramer <pg@fastcrypt.com>, Greg Stark <gsstark@mit.edu>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-id: <437F9919.20305@paradise.net.nz> +MIME-version: 1.0 +Content-type: text/plain; format=flowed; charset=ISO-8859-1 +Content-transfer-encoding: 7bit +X-Accept-Language: en-us, en +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20051106) +References: <BFA3ABF0.14124%llonergan@greenplum.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.666 required=5 tests=[AWL=0.666] +X-Spam-Score: 0.666 +X-Spam-Level: +X-Archive-Number: 200511/404 +X-Sequence-Number: 15661 + +Luke Lonergan wrote: +> Mark, +> +> On 11/18/05 3:46 PM, "Mark Kirkwood" <markir@paradise.net.nz> wrote: +> +> +>>If you alter this to involve more complex joins (e.g 4. way star) and +>>(maybe add a small number of concurrent executors too) - is it still the +>>case? +> +> +> 4-way star, same result, that's part of my point. With Bizgres MPP, the +> 4-way star uses 4 concurrent scanners, though not all are active all the +> time. And that's per segment instance - we normally use one segment +> instance per CPU, so our concurrency is NCPUs plus some. +> + +Luke - I don't think I was clear enough about what I was asking, sorry. + +I added the more "complex joins" comment because: + +- I am happy that seqscan is cpu bound after ~110M/s (It's cpu bound on +my old P3 system even earlier than that....) +- I am curious if the *other* access methods (indexscan, nested loop, +hash, merge, bitmap) also suffer then same fate. + +I'm guessing from your comment that you have tested this too, but I +think its worth clarifying! + +With respect to Bizgres MPP, scan parallelism is a great addition... +very nice! (BTW - is that in 0.8, or are we talking a new product variant?) + +regards + +Mark + + + +From pgsql-performance-owner@postgresql.org Sat Nov 19 22:45:24 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 514C7DB9FC + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 19 Nov 2005 22:45:23 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 46667-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 02:45:26 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id 8D5E6DB9EB + for <pgsql-performance@postgresql.org>; + Sat, 19 Nov 2005 22:45:20 -0400 (AST) +Received: from ram.rentec.com (mailhost [192.5.35.66]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jAK2iqcu017133 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Sat, 19 Nov 2005 21:44:53 -0500 (EST) +X-Source: non-mednet +Received: from [172.16.160.106] (stangesun.rentec.com [172.16.160.106]) + by ram.rentec.com (8.13.1/8.12.1) with ESMTP id jAK2iGLq006668; + Sat, 19 Nov 2005 21:44:17 -0500 (EST) +Message-ID: <437FE2E4.5040600@rentec.com> +Date: Sat, 19 Nov 2005 21:43:48 -0500 +From: Alan Stange <stange@rentec.com> +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Luke Lonergan <llonergan@greenplum.com> +CC: Greg Stark <gsstark@mit.edu>, Dave Cramer <pg@fastcrypt.com>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA48F15.14182%llonergan@greenplum.com> +In-Reply-To: <BFA48F15.14182%llonergan@greenplum.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jAK2iqcu017133 at Sat Nov 19 + 21:44:53 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.015 required=5 tests=[AWL=0.015] +X-Spam-Score: 0.015 +X-Spam-Level: +X-Archive-Number: 200511/405 +X-Sequence-Number: 15662 + +Luke Lonergan wrote: +> Alan, +> +> On 11/18/05 11:39 AM, "Alan Stange" <stange@rentec.com> wrote: +> +> +>> Yes and no. The one cpu is clearly idle. The second cpu is 40% busy +>> and 60% idle (aka iowait in the above numbers). +>> +> +> The "aka iowait" is the problem here - iowait is not idle (otherwise it +> would be in the "idle" column). +> +> Iowait is time spent waiting on blocking io calls. As another poster +> pointed out, you have a two CPU system, and during your scan, as predicted, +> one CPU went 100% busy on the seq scan. During iowait periods, the CPU can +> be context switched to other users, but as I pointed out earlier, that's not +> useful for getting response on decision support queries. +> +iowait time is idle time. Period. This point has been debated +endlessly for Solaris and other OS's as well. + +Here's the man page: + %iowait + Show the percentage of time that the CPU or +CPUs were + idle during which the system had an outstanding +disk I/O + request. + +If the system had some other cpu bound work to perform you wouldn't ever +see any iowait time. Anyone claiming the cpu was 100% busy on the +sequential scan using the one set of numbers I posted is +misunderstanding the actual metrics. + +> Thanks for your data, it exemplifies many of the points brought up: +> - Lots of disks and expensive I/O hardware does not help improve performance +> on large table queries because I/O bandwidth does not scale beyond +> 110-120MB/s on the fastest CPUs +> +I don't think that is the conclusion from anecdotal numbers I posted. +This file subsystem doesn't perform as well as expected for any tool. +Bonnie, dd, star, etc., don't get a better data rate either. In fact, +the storage system wasn't built for performance; it was build to +reliably hold a big chunk of data. Even so, postgresql is reading at +130MB/s on it, using about 30% of a single cpu, almost all of which was +system time. I would get the same 130MB/s on a system with cpus that +were substantially slower; the limitation isn't the cpus, or +postgresql. It's the IO system that is poorly configured for this test, +not postgresqls ability to use it. + +In fact, given the numbers I posted, it's clear this system could +handily generate more than 120 MB/s using a single cpu given a better IO +subsystem; it has cpu time to spare. A simple test can be done: +build the database in /dev/shm and time the scans. It's the same read() +system call being used and now one has made the IO system "infinitely +fast". The claim is being made that standard postgresql is unable to +generate more than 120MB/s of IO on any IO system due to an inefficient +use of the kernel API and excessive memory copies, etc. Having the +database be on a ram based file system is an example of "expensive IO +hardware" and all else would be the same. Hmmm, now that I think about +this, I could throw a medium sized table onto /dev/shm using +tablespaces on one of our 8GB linux boxes. So why is this experiment +not valid, or what is it about the above assertion that I am missing? + + +Anyway, if one cares about high speed sequential IO, then one should use +a much larger block size to start. Using 8KB IOs is inappropriate for +such a configuration. We happen to be using 32KB blocks on our largest +database and it's been the best move for us. + +-- Alan + +From pgsql-performance-owner@postgresql.org Sun Nov 20 00:44:48 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 1B1C7DBAA1 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 00:44:48 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 65216-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 04:44:46 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id 7A87BDB9EB + for <pgsql-performance@postgresql.org>; + Sun, 20 Nov 2005 00:44:45 -0400 (AST) +Received: from ram.rentec.com (mailhost [192.5.35.66]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jAK4iRR6019192 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Sat, 19 Nov 2005 23:44:28 -0500 (EST) +X-Source: non-mednet +Received: from [172.16.160.106] (stangesun.rentec.com [172.16.160.106]) + by ram.rentec.com (8.13.1/8.12.1) with ESMTP id jAK4huxL014736; + Sat, 19 Nov 2005 23:43:56 -0500 (EST) +Message-ID: <437FFEF0.9090409@rentec.com> +Date: Sat, 19 Nov 2005 23:43:28 -0500 +From: Alan Stange <stange@rentec.com> +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Luke Lonergan <llonergan@greenplum.com> +CC: Greg Stark <gsstark@mit.edu>, Dave Cramer <pg@fastcrypt.com>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA48F15.14182%llonergan@greenplum.com> +In-Reply-To: <BFA48F15.14182%llonergan@greenplum.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jAK4iRR6019192 at Sat Nov 19 + 23:44:28 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.013 required=5 tests=[AWL=0.013] +X-Spam-Score: 0.013 +X-Spam-Level: +X-Archive-Number: 200511/406 +X-Sequence-Number: 15663 + +Another data point. + +We had some down time on our system today to complete some maintenance +work. It took the opportunity to rebuild the 700GB file system using +XFS instead of Reiser. + +One iostat output for 30 seconds is + +avg-cpu: %user %nice %sys %iowait %idle + 1.58 0.00 19.69 31.94 46.78 + +Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn +sdd 343.73 175035.73 277.55 5251072 8326 + +while doing a select count(1) on the same large table as before. +Subsequent iostat output all showed that this data rate was being +maintained. The system is otherwise mostly idle during this measurement. + +The sequential read rate is 175MB/s. The system is the same as earlier, +one cpu is idle and the second is ~40% busy doing the scan and ~60% +idle. This is postgresql 8.1rc1, 32KB block size. No tuning except +for using a 1024KB read ahead. + +The peak speed of the attached storage is 200MB/s (a 2Gb/s fiber channel +controller). I see no reason why this configuration wouldn't generate +higher IO rates if a faster IO connection were available. + +Can you explain again why you think there's an IO ceiling of 120MB/s +because I really don't understand? + +-- Alan + + + +From pgsql-performance-owner@postgresql.org Sun Nov 20 04:56:08 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5E3E1D70DD + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 04:56:06 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 24299-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 08:56:07 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from linda-4.paradise.net.nz (bm-4a.paradise.net.nz + [203.96.152.183]) + by svr1.postgresql.org (Postfix) with ESMTP id DB76AD6EEA + for <pgsql-performance@postgresql.org>; + Sun, 20 Nov 2005 04:56:03 -0400 (AST) +Received: from smtp-1.paradise.net.nz + (tclsnelb2-src-1.paradise.net.nz [203.96.152.177]) by + linda-4.paradise.net.nz (Paradise.net.nz) with ESMTP id + <0IQ800FNCWTGCJ@linda-4.paradise.net.nz> for + pgsql-performance@postgresql.org; Sun, 20 Nov 2005 21:56:04 +1300 (NZDT) +Received: from [192.168.1.11] (218-101-29-89.dsl.clear.net.nz [218.101.29.89]) + by smtp-1.paradise.net.nz (Postfix) with ESMTP id 343DDFBDC83; Sun, + 20 Nov 2005 21:56:04 +1300 (NZDT) +Date: Sun, 20 Nov 2005 21:55:59 +1300 +From: Mark Kirkwood <markir@paradise.net.nz> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <437F9919.20305@paradise.net.nz> +To: Mark Kirkwood <markir@paradise.net.nz> +Cc: Luke Lonergan <llonergan@greenplum.com>, pgsql-performance@postgresql.org, + stange@rentec.com, gsstark@mit.edu, pg@fastcrypt.com, icub3d@gmail.com +Message-id: <43803A1F.9030708@paradise.net.nz> +MIME-version: 1.0 +Content-type: text/plain; format=flowed; charset=ISO-8859-1 +Content-transfer-encoding: 7bit +X-Accept-Language: en-us, en +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20051106) +References: <BFA3ABF0.14124%llonergan@greenplum.com> + <437F9919.20305@paradise.net.nz> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.499 required=5 tests=[AWL=0.499] +X-Spam-Score: 0.499 +X-Spam-Level: +X-Archive-Number: 200511/407 +X-Sequence-Number: 15664 + +Mark Kirkwood wrote: + +> +> - I am happy that seqscan is cpu bound after ~110M/s (It's cpu bound on +> my old P3 system even earlier than that....) + +Ahem - after reading Alan's postings I am not so sure, ISTM that there +is some more investigation required here too :-). + + + +From pgsql-performance-owner@postgresql.org Sun Nov 20 08:55:18 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id AEE62D7331 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 08:55:17 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 76131-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 12:55:18 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (floppy.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id B8EFFD6810 + for <pgsql-performance@postgresql.org>; + Sun, 20 Nov 2005 08:55:13 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id D248C31059; Sun, 20 Nov 2005 13:55:16 +0100 (MET) +From: William Yu <wyu@talisys.com> +X-Newsgroups: pgsql.performance +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Sun, 20 Nov 2005 04:55:14 -0800 +Organization: Hub.Org Networking Services +Lines: 24 +Message-ID: <dlprnd$25d0$1@news.hub.org> +References: <BFA48F15.14182%llonergan@greenplum.com> + <437FE2E4.5040600@rentec.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Complaints-To: usenet@news.hub.org +User-Agent: Mozilla Thunderbird 1.0 (X11/20041206) +X-Accept-Language: en-us, en +In-Reply-To: <437FE2E4.5040600@rentec.com> +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/408 +X-Sequence-Number: 15665 + +Alan Stange wrote: +> Luke Lonergan wrote: +>> The "aka iowait" is the problem here - iowait is not idle (otherwise it +>> would be in the "idle" column). +>> +>> Iowait is time spent waiting on blocking io calls. As another poster +>> pointed out, you have a two CPU system, and during your scan, as +> +> iowait time is idle time. Period. This point has been debated +> endlessly for Solaris and other OS's as well. + +I'm sure the the theory is nice but here's my experience with iowait +just a minute ago. I run Linux/XFce as my desktop -- decided I wanted to +lookup some stuff in Wikipedia under Mozilla and my computer system +became completely unusable for nearly a minute while who knows what +Mozilla was doing. (Probably loading all the language packs.) I could +not even switch to IRC (already loaded) to chat with other people while +Mozilla was chewing up all my disk I/O. + +So I went to another computer, connected to mine remotely (slow...) and +checked top. 90% in the "wa" column which I assume is the iowait column. +It may be idle in theory but it's not a very useful idle -- wasn't able +to switch to any programs already running, couldn't click on the XFce +launchbar to run any new programs. + +From pgsql-performance-owner@postgresql.org Sun Nov 20 09:25:10 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D396FD76A6 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 09:25:09 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 79129-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 13:25:12 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from cassarossa.samfundet.no (cassarossa.samfundet.no + [129.241.93.19]) + by svr1.postgresql.org (Postfix) with ESMTP id CDF4CD735B + for <pgsql-performance@postgresql.org>; + Sun, 20 Nov 2005 09:05:24 -0400 (AST) +Received: from trofast.ipv6.sesse.net ([2001:700:300:dc03:20e:cff:fe36:a766] + helo=trofast.sesse.net) + by cassarossa.samfundet.no with esmtp (Exim 4.50) id 1Edosn-0003oP-MP + for pgsql-performance@postgresql.org; Sun, 20 Nov 2005 14:05:27 +0100 +Received: from sesse by trofast.sesse.net with local (Exim 3.36 #1 (Debian)) + id 1Edos2-0008Bd-00 + for <pgsql-performance@postgresql.org>; Sun, 20 Nov 2005 14:04:38 +0100 +Date: Sun, 20 Nov 2005 14:04:38 +0100 +From: "Steinar H. Gunderson" <sgunderson@bigfoot.com> +To: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +Message-ID: <20051120130438.GA31206@uio.no> +Mail-Followup-To: pgsql-performance@postgresql.org +References: <437E2DF2.50906@rentec.com> + <BFA48F15.14182%llonergan@greenplum.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=utf-8 +Content-Disposition: inline +In-Reply-To: <BFA48F15.14182%llonergan@greenplum.com> +X-Operating-System: Linux 2.6.14 on a i686 +X-Message-Flag: Outlook? --> http://www.mozilla.org/products/thunderbird/ +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/409 +X-Sequence-Number: 15666 + +On Sat, Nov 19, 2005 at 08:13:09AM -0800, Luke Lonergan wrote: +> Iowait is time spent waiting on blocking io calls. + +To be picky, iowait is time spent in the idle task while the I/O queue is not +empty. It does not matter if the I/O is blocking or not (from userspace's +point of view), and if the I/O was blocking (say, PIO) from the kernel's +point of view, it would be counted in system. + +/* Steinar */ +-- +Homepage: http://www.sesse.net/ + +From pgsql-performance-owner@postgresql.org Sun Nov 20 09:43:17 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 02056D77D6 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 09:43:17 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 80852-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 13:43:19 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id 696ADD735B + for <pgsql-performance@postgresql.org>; + Sun, 20 Nov 2005 09:43:13 -0400 (AST) +Received: from ram.rentec.com (mailhost [192.5.35.66]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jAKDh985005224 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Sun, 20 Nov 2005 08:43:10 -0500 (EST) +X-Source: non-mednet +Received: from [172.16.160.106] (stangesun.rentec.com [172.16.160.106]) + by ram.rentec.com (8.13.1/8.12.1) with ESMTP id jAKDgbxH026842; + Sun, 20 Nov 2005 08:42:38 -0500 (EST) +Message-ID: <43807D31.6050008@rentec.com> +Date: Sun, 20 Nov 2005 08:42:09 -0500 +From: Alan Stange <stange@rentec.com> +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: William Yu <wyu@talisys.com> +CC: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA48F15.14182%llonergan@greenplum.com> + <437FE2E4.5040600@rentec.com> <dlprnd$25d0$1@news.hub.org> +In-Reply-To: <dlprnd$25d0$1@news.hub.org> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jAKDh985005224 at Sun Nov 20 + 08:43:10 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.011 required=5 tests=[AWL=0.011] +X-Spam-Score: 0.011 +X-Spam-Level: +X-Archive-Number: 200511/410 +X-Sequence-Number: 15667 + +William Yu wrote: +> Alan Stange wrote: +>> Luke Lonergan wrote: +>>> The "aka iowait" is the problem here - iowait is not idle (otherwise it +>>> would be in the "idle" column). +>>> +>>> Iowait is time spent waiting on blocking io calls. As another poster +>>> pointed out, you have a two CPU system, and during your scan, as +>> +>> iowait time is idle time. Period. This point has been debated +>> endlessly for Solaris and other OS's as well. +> +> I'm sure the the theory is nice but here's my experience with iowait +> just a minute ago. I run Linux/XFce as my desktop -- decided I wanted +> to lookup some stuff in Wikipedia under Mozilla and my computer system +> became completely unusable for nearly a minute while who knows what +> Mozilla was doing. (Probably loading all the language packs.) I could +> not even switch to IRC (already loaded) to chat with other people +> while Mozilla was chewing up all my disk I/O. +> +> So I went to another computer, connected to mine remotely (slow...) +> and checked top. 90% in the "wa" column which I assume is the iowait +> column. It may be idle in theory but it's not a very useful idle -- +> wasn't able to switch to any programs already running, couldn't click +> on the XFce launchbar to run any new programs. + +So, you have a sucky computer. I'm sorry, but iowait is still idle +time, whether you believe it or not. + +-- Alan + + +From pgsql-performance-owner@postgresql.org Sun Nov 20 10:22:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 74ACDD781A + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 10:22:45 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 83439-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 14:22:48 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from stark.xeocode.com (stark.xeocode.com [216.58.44.227]) + by svr1.postgresql.org (Postfix) with ESMTP id DE239D77D6 + for <pgsql-performance@postgresql.org>; + Sun, 20 Nov 2005 10:22:42 -0400 (AST) +Received: from localhost ([127.0.0.1] helo=stark.xeocode.com) + by stark.xeocode.com with smtp (Exim 3.36 #1 (Debian)) + id 1Edq5Z-0003EU-00; Sun, 20 Nov 2005 09:22:41 -0500 +To: Alan Stange <stange@rentec.com> +Cc: Luke Lonergan <llonergan@greenplum.com>, Greg Stark <gsstark@mit.edu>, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA48F15.14182%llonergan@greenplum.com> + <437FE2E4.5040600@rentec.com> +In-Reply-To: <437FE2E4.5040600@rentec.com> +From: Greg Stark <gsstark@mit.edu> +Organization: The Emacs Conspiracy; member since 1992 +Date: 20 Nov 2005 09:22:41 -0500 +Message-ID: <87y83jo0um.fsf@stark.xeocode.com> +Lines: 34 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/411 +X-Sequence-Number: 15668 + + +Alan Stange <stange@rentec.com> writes: + +> > Iowait is time spent waiting on blocking io calls. As another poster +> > pointed out, you have a two CPU system, and during your scan, as predicted, +> > one CPU went 100% busy on the seq scan. During iowait periods, the CPU can +> > be context switched to other users, but as I pointed out earlier, that's not +> > useful for getting response on decision support queries. + +I don't think that's true. If the syscall was preemptable then it wouldn't +show up under "iowait", but rather "idle". The time spent in iowait is time in +uninterruptable sleeps where no other process can be scheduled. + +> iowait time is idle time. Period. This point has been debated endlessly for +> Solaris and other OS's as well. +> +> Here's the man page: +> %iowait +> Show the percentage of time that the CPU or CPUs were +> idle during which the system had an outstanding disk I/O +> request. +> +> If the system had some other cpu bound work to perform you wouldn't ever see +> any iowait time. Anyone claiming the cpu was 100% busy on the sequential scan +> using the one set of numbers I posted is misunderstanding the actual metrics. + +That's easy to test. rerun the test with another process running a simple C +program like "main() {while(1);}" (or two invocations of that on your system +because of the extra processor). I bet you'll see about half the percentage of +iowait because postres will get half as much opportunity to schedule i/o. If +what you are saying were true then you should get 0% iowait. + +-- +greg + + +From pgsql-performance-owner@postgresql.org Sun Nov 20 10:30:26 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 826CDD78D2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 10:30:24 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 84004-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 14:30:25 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from cassarossa.samfundet.no (cassarossa.samfundet.no + [129.241.93.19]) + by svr1.postgresql.org (Postfix) with ESMTP id C8329D70A1 + for <pgsql-performance@postgresql.org>; + Sun, 20 Nov 2005 10:30:19 -0400 (AST) +Received: from trofast.sesse.net ([129.241.93.32]) + by cassarossa.samfundet.no with esmtp (Exim 4.50) id 1EdqCz-0002Bi-QQ + for pgsql-performance@postgresql.org; Sun, 20 Nov 2005 15:30:23 +0100 +Received: from sesse by trofast.sesse.net with local (Exim 3.36 #1 (Debian)) + id 1EdqCF-0008Pe-00 + for <pgsql-performance@postgresql.org>; Sun, 20 Nov 2005 15:29:35 +0100 +Date: Sun, 20 Nov 2005 15:29:35 +0100 +From: "Steinar H. Gunderson" <sgunderson@bigfoot.com> +To: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +Message-ID: <20051120142935.GA32311@uio.no> +Mail-Followup-To: pgsql-performance@postgresql.org +References: <BFA48F15.14182%llonergan@greenplum.com> + <437FE2E4.5040600@rentec.com> <87y83jo0um.fsf@stark.xeocode.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=utf-8 +Content-Disposition: inline +In-Reply-To: <87y83jo0um.fsf@stark.xeocode.com> +X-Operating-System: Linux 2.6.14 on a i686 +X-Message-Flag: Outlook? --> http://www.mozilla.org/products/thunderbird/ +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/412 +X-Sequence-Number: 15669 + +On Sun, Nov 20, 2005 at 09:22:41AM -0500, Greg Stark wrote: +> I don't think that's true. If the syscall was preemptable then it wouldn't +> show up under "iowait", but rather "idle". The time spent in iowait is time in +> uninterruptable sleeps where no other process can be scheduled. + +You are confusing userspace with kernel space. When a process is stuck in +uninterruptable sleep, it means _that process_ can't be interrupted (say, +by a signal). The kernel can preempt it without problems. + +/* Steinar */ +-- +Homepage: http://www.sesse.net/ + +From pgsql-performance-owner@postgresql.org Sun Nov 20 14:10:37 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9B26FD7D62 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 14:10:35 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14460-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 18:10:34 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id C9764D7A41 + for <pgsql-performance@postgresql.org>; + Sun, 20 Nov 2005 14:10:31 -0400 (AST) +Received: from ram.rentec.com (mailhost [192.5.35.66]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jAKIA7El011087 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Sun, 20 Nov 2005 13:10:08 -0500 (EST) +X-Source: non-mednet +Received: from [172.16.160.106] (stangesun.rentec.com [172.16.160.106]) + by ram.rentec.com (8.13.1/8.12.1) with ESMTP id jAKI9Y7u014332; + Sun, 20 Nov 2005 13:09:35 -0500 (EST) +Message-ID: <4380BBC2.7060109@rentec.com> +Date: Sun, 20 Nov 2005 13:09:06 -0500 +From: Alan Stange <stange@rentec.com> +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Greg Stark <gsstark@mit.edu> +CC: Luke Lonergan <llonergan@greenplum.com>, Dave Cramer <pg@fastcrypt.com>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA48F15.14182%llonergan@greenplum.com> + <437FE2E4.5040600@rentec.com> + <87y83jo0um.fsf@stark.xeocode.com> +In-Reply-To: <87y83jo0um.fsf@stark.xeocode.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jAKIA7El011087 at Sun Nov 20 + 13:10:08 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.01 required=5 tests=[AWL=0.010] +X-Spam-Score: 0.01 +X-Spam-Level: +X-Archive-Number: 200511/413 +X-Sequence-Number: 15670 + +Greg Stark wrote: +> Alan Stange <stange@rentec.com> writes: +> +> +>>> Iowait is time spent waiting on blocking io calls. As another poster +>>> pointed out, you have a two CPU system, and during your scan, as predicted, +>>> one CPU went 100% busy on the seq scan. During iowait periods, the CPU can +>>> be context switched to other users, but as I pointed out earlier, that's not +>>> useful for getting response on decision support queries. +>>> +> +> I don't think that's true. If the syscall was preemptable then it wouldn't +> show up under "iowait", but rather "idle". The time spent in iowait is time in +> uninterruptable sleeps where no other process can be scheduled. +> +That would be wrong. The time spent in iowait is idle time. The +iowait stat would be 0 on a machine with a compute bound runnable +process available for each cpu. + +Come on people, read the man page or look at the source code. Just +stop making stuff up. + + +> +>> iowait time is idle time. Period. This point has been debated endlessly for +>> Solaris and other OS's as well. +>> +>> Here's the man page: +>> %iowait +>> Show the percentage of time that the CPU or CPUs were +>> idle during which the system had an outstanding disk I/O +>> request. +>> +>> If the system had some other cpu bound work to perform you wouldn't ever see +>> any iowait time. Anyone claiming the cpu was 100% busy on the sequential scan +>> using the one set of numbers I posted is misunderstanding the actual metrics. +>> +> +> That's easy to test. rerun the test with another process running a simple C +> program like "main() {while(1);}" (or two invocations of that on your system +> because of the extra processor). I bet you'll see about half the percentage of +> iowait because postres will get half as much opportunity to schedule i/o. If +> what you are saying were true then you should get 0% iowait. +Yes, I did this once about 10 years ago. But instead of saying "I bet" +and guessing at the result, you should try it yourself. Without +guessing, I can tell you that the iowait time will go to 0%. You can do +this loop in the shell, so there's no code to write. Also, it helps to +do this with the shell running at a lower priority. + +-- Alan + + + +From pgsql-performance-owner@postgresql.org Sun Nov 20 17:48:52 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 77082D6E94 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 17:48:51 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 52416-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 21:48:52 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from moonunit2.moonview.localnet (wsip-68-15-5-150.sd.sd.cox.net + [68.15.5.150]) + by svr1.postgresql.org (Postfix) with ESMTP id 8C16AD6833 + for <pgsql-performance@postgresql.org>; + Sun, 20 Nov 2005 17:48:48 -0400 (AST) +Received: from [192.168.0.3] (moonunit3.moonview.localnet [192.168.0.3]) + by moonunit2.moonview.localnet (8.13.1/8.13.1) with ESMTP id + jAKLvekp027710 + for <pgsql-performance@postgresql.org>; Sun, 20 Nov 2005 13:57:40 -0800 +Message-ID: <4380EEA2.4010002@modgraph-usa.com> +Date: Sun, 20 Nov 2005 13:46:10 -0800 +From: "Craig A. James" <cjames@modgraph-usa.com> +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20050716) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +CC: pgsql-performance@postgresql.org +Subject: Hyperthreading slows processes? +References: <BF9F6C0E.13B4A%llonergan@greenplum.com> + <1132136225.5711.4.camel@Panoramix> + <437B9DA9.2030806@modgraph-usa.com> + <20051117002344.GA55377@winnie.fuhr.org> + <437CF055.6020602@modgraph-usa.com> + <20051117232857.GA49910@winnie.fuhr.org> + <437D3085.9040207@modgraph-usa.com> + <20051118034631.GA70159@winnie.fuhr.org> + <437F66CF.7080402@modgraph-usa.com> + <20051119190304.GJ7330@mathom.us> +In-Reply-To: <20051119190304.GJ7330@mathom.us> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.118 required=5 tests=[AWL=-0.071, + MISSING_HEADERS=0.189] +X-Spam-Score: 0.118 +X-Spam-Level: +X-Archive-Number: 200511/414 +X-Sequence-Number: 15671 + +This article on ZDNet claims that hyperthreading can *hurt* performance, due to contention in the L1/L2 cache by a second process: + + http://news.zdnet.co.uk/0,39020330,39237341,00.htm + +Has anyone tested this on Postgres yet? (And based on a recent somewhat caustic thread about performance on this forum, I'm going to avoid speculation, and let those who actually *know* answer! ;-) + +Craig + +From pgsql-performance-owner@postgresql.org Sun Nov 20 20:11:25 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 1DA06D7080 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 20:11:24 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 81489-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 00:11:25 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from linda-5.paradise.net.nz (bm-5a.paradise.net.nz + [203.96.152.184]) + by svr1.postgresql.org (Postfix) with ESMTP id 75618D6E94 + for <pgsql-performance@postgresql.org>; + Sun, 20 Nov 2005 20:11:21 -0400 (AST) +Received: from smtp-3.paradise.net.nz + (tclsnelb2-src-1.paradise.net.nz [203.96.152.177]) by + linda-5.paradise.net.nz (Paradise.net.nz) with ESMTP id + <0IQA00JIY36U82@linda-5.paradise.net.nz> for + pgsql-performance@postgresql.org; Mon, 21 Nov 2005 13:11:18 +1300 (NZDT) +Received: from [192.168.1.11] + (218-101-28-198.dsl.clear.net.nz [218.101.28.198]) by + smtp-3.paradise.net.nz (Postfix) with ESMTP id 42EB9D5DD5B; + Mon, 21 Nov 2005 13:11:17 +1300 (NZDT) +Date: Mon, 21 Nov 2005 13:11:15 +1300 +From: Mark Kirkwood <markir@paradise.net.nz> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <437FFEF0.9090409@rentec.com> +To: Alan Stange <stange@rentec.com> +Cc: Luke Lonergan <llonergan@greenplum.com>, Greg Stark <gsstark@mit.edu>, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Message-id: <438110A3.20506@paradise.net.nz> +MIME-version: 1.0 +Content-type: text/plain; format=flowed; charset=ISO-8859-1 +Content-transfer-encoding: 7bit +X-Accept-Language: en-us, en +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20051106) +References: <BFA48F15.14182%llonergan@greenplum.com> + <437FFEF0.9090409@rentec.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.4 required=5 tests=[AWL=0.400] +X-Spam-Score: 0.4 +X-Spam-Level: +X-Archive-Number: 200511/415 +X-Sequence-Number: 15672 + +Alan Stange wrote: +> Another data point. +> We had some down time on our system today to complete some maintenance +> work. It took the opportunity to rebuild the 700GB file system using +> XFS instead of Reiser. +> +> One iostat output for 30 seconds is +> +> avg-cpu: %user %nice %sys %iowait %idle +> 1.58 0.00 19.69 31.94 46.78 +> +> Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn +> sdd 343.73 175035.73 277.55 5251072 8326 +> +> while doing a select count(1) on the same large table as before. +> Subsequent iostat output all showed that this data rate was being +> maintained. The system is otherwise mostly idle during this measurement. +> +> The sequential read rate is 175MB/s. The system is the same as earlier, +> one cpu is idle and the second is ~40% busy doing the scan and ~60% +> idle. This is postgresql 8.1rc1, 32KB block size. No tuning except +> for using a 1024KB read ahead. +> +> The peak speed of the attached storage is 200MB/s (a 2Gb/s fiber channel +> controller). I see no reason why this configuration wouldn't generate +> higher IO rates if a faster IO connection were available. +> +> Can you explain again why you think there's an IO ceiling of 120MB/s +> because I really don't understand? +> + +I think what is going on here is that Luke's observation of the 120 Mb/s +rate is taken from data using 8K block size - it looks like we can get +higher rates with 32K. + +A quick test on my P3 system seems to support this (the numbers are a +bit feeble, but the difference is interesting): + +The test is SELECT 1 FROM table, stopping Pg and unmounting the file +system after each test. + +8K blocksize: +25 s elapsed +48 % idle from vmstat (dual cpu system) +70 % busy from gstat (Freebsd GEOM io monitor) +181819 pages in relation +56 Mb/s effective IO throughput + + +32K blocksize: +23 s elapsed +44 % idle from vmstat +80 % busy from gstat +45249 pages in relation +60 Mb/s effective IO throughput + + +I re-ran these several times - very repeatable (+/- 0.25 seconds). + +This is Freebsd 6.0 with the readahead set to 16 blocks, UFS2 filesystem +created with 32K blocksize (both cases). It might be interesting to see +the effect of using 16K (the default) with the 8K Pg block size, I would +expect this to widen the gap. + +Cheers + +Mark + + +From pgsql-performance-owner@postgresql.org Sun Nov 20 21:24:32 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 99159D855B + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 21:24:31 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 89289-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 01:24:31 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from net2.micro-automation.com (net2.micro-automation.com + [64.7.141.29]) + by svr1.postgresql.org (Postfix) with SMTP id 7C431D6E94 + for <pgsql-performance@postgresql.org>; + Sun, 20 Nov 2005 21:24:25 -0400 (AST) +Received: (qmail 1699 invoked from network); 21 Nov 2005 01:24:26 -0000 +Received: from dcdsl.ebox.com (HELO ?192.168.1.2?) (davec@64.7.143.116) + by net2.micro-automation.com with SMTP; 21 Nov 2005 01:24:26 -0000 +In-Reply-To: <4380EEA2.4010002@modgraph-usa.com> +References: <BF9F6C0E.13B4A%llonergan@greenplum.com> + <1132136225.5711.4.camel@Panoramix> + <437B9DA9.2030806@modgraph-usa.com> + <20051117002344.GA55377@winnie.fuhr.org> + <437CF055.6020602@modgraph-usa.com> + <20051117232857.GA49910@winnie.fuhr.org> + <437D3085.9040207@modgraph-usa.com> + <20051118034631.GA70159@winnie.fuhr.org> + <437F66CF.7080402@modgraph-usa.com> + <20051119190304.GJ7330@mathom.us> + <4380EEA2.4010002@modgraph-usa.com> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: <C875A76F-AC09-4207-97D6-DE7969244146@fastcrypt.com> +Cc: pgsql-performance@postgresql.org +Content-Transfer-Encoding: 7bit +From: Dave Cramer <pg@fastcrypt.com> +Subject: Re: Hyperthreading slows processes? +Date: Sun, 20 Nov 2005 20:24:24 -0500 +To: Craig A. James <cjames@modgraph-usa.com> +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.014 required=5 tests=[AWL=0.014] +X-Spam-Score: 0.014 +X-Spam-Level: +X-Archive-Number: 200511/416 +X-Sequence-Number: 15673 + +Yeah, it's pretty much a known issue for postgres + +Dave +On 20-Nov-05, at 4:46 PM, Craig A. James wrote: + +> This article on ZDNet claims that hyperthreading can *hurt* +> performance, due to contention in the L1/L2 cache by a second process: +> +> http://news.zdnet.co.uk/0,39020330,39237341,00.htm +> +> Has anyone tested this on Postgres yet? (And based on a recent +> somewhat caustic thread about performance on this forum, I'm going +> to avoid speculation, and let those who actually *know* answer! ;-) +> +> Craig +> +> ---------------------------(end of +> broadcast)--------------------------- +> TIP 4: Have you searched our list archives? +> +> http://archives.postgresql.org +> + + +From pgsql-performance-owner@postgresql.org Sun Nov 20 21:41:15 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id E03D4D8216 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 20 Nov 2005 21:41:14 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 90856-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 01:41:17 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from linda-1.paradise.net.nz (bm-1a.paradise.net.nz + [203.96.152.180]) + by svr1.postgresql.org (Postfix) with ESMTP id 49577D7FCE + for <pgsql-performance@postgresql.org>; + Sun, 20 Nov 2005 21:41:11 -0400 (AST) +Received: from smtp-1.paradise.net.nz (tclsnelbe2-src-nat-1 [203.96.152.177]) + by linda-1.paradise.net.nz (Paradise.net.nz) + with ESMTP id <0IQA00APC7C9QN@linda-1.paradise.net.nz> for + pgsql-performance@postgresql.org; Mon, 21 Nov 2005 14:40:57 +1300 (NZDT) +Received: from [192.168.1.11] + (218-101-28-198.dsl.clear.net.nz [218.101.28.198]) by + smtp-1.paradise.net.nz (Postfix) with ESMTP id 9D245129F391; + Mon, 21 Nov 2005 14:40:56 +1300 (NZDT) +Date: Mon, 21 Nov 2005 14:40:54 +1300 +From: Mark Kirkwood <markir@paradise.net.nz> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <438110A3.20506@paradise.net.nz> +To: Mark Kirkwood <markir@paradise.net.nz> +Cc: Alan Stange <stange@rentec.com>, Luke Lonergan <llonergan@greenplum.com>, + Greg Stark <gsstark@mit.edu>, Dave Cramer <pg@fastcrypt.com>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-id: <438125A6.2040200@paradise.net.nz> +MIME-version: 1.0 +Content-type: text/plain; format=flowed; charset=ISO-8859-1 +Content-transfer-encoding: 7bit +X-Accept-Language: en-us, en +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20051106) +References: <BFA48F15.14182%llonergan@greenplum.com> + <437FFEF0.9090409@rentec.com> <438110A3.20506@paradise.net.nz> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.333 required=5 tests=[AWL=0.333] +X-Spam-Score: 0.333 +X-Spam-Level: +X-Archive-Number: 200511/417 +X-Sequence-Number: 15674 + +Mark Kirkwood wrote: + +> The test is SELECT 1 FROM table + +That should read "The test is SELECT count(1) FROM table...." + +From pgsql-performance-owner@postgresql.org Mon Nov 21 04:13:12 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0A8BAD78B8 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 04:13:11 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 81741-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 08:13:11 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw03.mi8.com [63.240.6.42]) + by svr1.postgresql.org (Postfix) with ESMTP id 19771D94E5 + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 04:13:07 -0400 (AST) +Received: from 172.16.1.112 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D3)); Mon, 21 Nov 2005 03:12:58 -0500 +X-Server-Uuid: E847189C-FC88-4913-9CD4-DE66914F83C0 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Mon, 21 Nov + 2005 03:12:58 -0500 +Received: from 208.54.15.129 ([208.54.15.129]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Mon, 21 Nov + 2005 03:12:57 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Mon, 21 Nov 2005 00:12:55 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Alan Stange" <stange@rentec.com> +cc: "Greg Stark" <gsstark@mit.edu>, "Dave Cramer" <pg@fastcrypt.com>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-ID: <BFA6C187.1425C%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXtjSIct5lGn9A0TIO+AtPmVX3wYQA5j3wv +In-Reply-To: <437FFEF0.9090409@rentec.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 21 Nov 2005 08:12:58.0110 (UTC) + FILETIME=[61E6E9E0:01C5EE73] +X-WSS-ID: 6F9F5E002BW10867735-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.253 required=5 tests=[RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.253 +X-Spam-Level: * +X-Archive-Number: 200511/418 +X-Sequence-Number: 15675 + +Alan, + + +On 11/19/05 8:43 PM, "Alan Stange" <stange@rentec.com> wrote: + +> Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn +> sdd 343.73 175035.73 277.55 5251072 8326 +> +> while doing a select count(1) on the same large table as before. +> Subsequent iostat output all showed that this data rate was being +> maintained. The system is otherwise mostly idle during this measurement. + +Yes - interesting. Note the other result using XFS that I posted earlier +where I got 240+MB/s. XFS has more aggressive readahead, which is why I +used it. + +> Can you explain again why you think there's an IO ceiling of 120MB/s +> because I really don't understand? + +OK - slower this time: + +We've seen between 110MB/s and 120MB/s on a wide variety of fast CPU +machines with fast I/O subsystems that can sustain 250MB/s+ using dd, but +which all are capped at 120MB/s when doing sequential scans with different +versions of Postgres. + +Understand my point: It doesn't matter that there is idle or iowait on the +CPU, the postgres executor is not able to drive the I/O rate for two +reasons: there is a lot of CPU used for the scan (the 40% you reported) and +a lack of asynchrony (the iowait time). That means that by speeding up the +CPU you only reduce the first part, but you don't fix the second and v.v. + +With more aggressive readahead, the second problem (the I/O asynchrony) is +handled better by the Linux kernel and filesystem. That's what we're seeing +with XFS. + +- Luke + + + +From pgsql-performance-owner@postgresql.org Mon Nov 21 10:57:09 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 50540D9E93 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 10:57:08 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 33574-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 14:57:11 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 6B417D9BAB + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 10:57:05 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jALEuk8u001612; + Mon, 21 Nov 2005 09:56:46 -0500 (EST) +To: "Luke Lonergan" <llonergan@greenplum.com> +cc: "Alan Stange" <stange@rentec.com>, "Greg Stark" <gsstark@mit.edu>, + "Dave Cramer" <pg@fastcrypt.com>, "Joshua Marsh" <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <BFA6C187.1425C%llonergan@greenplum.com> +References: <BFA6C187.1425C%llonergan@greenplum.com> +Comments: In-reply-to "Luke Lonergan" <llonergan@greenplum.com> + message dated "Mon, 21 Nov 2005 00:12:55 -0800" +Date: Mon, 21 Nov 2005 09:56:46 -0500 +Message-ID: <1611.1132585006@sss.pgh.pa.us> +From: Tom Lane <tgl@sss.pgh.pa.us> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.004 required=5 tests=[AWL=0.004] +X-Spam-Score: 0.004 +X-Spam-Level: +X-Archive-Number: 200511/419 +X-Sequence-Number: 15676 + +"Luke Lonergan" <llonergan@greenplum.com> writes: +> OK - slower this time: + +> We've seen between 110MB/s and 120MB/s on a wide variety of fast CPU +> machines with fast I/O subsystems that can sustain 250MB/s+ using dd, but +> which all are capped at 120MB/s when doing sequential scans with different +> versions of Postgres. + +Luke, sometime it would be nice if you would post your raw evidence +and let other people do their own analysis. I for one have gotten +tired of reading sweeping generalizations unbacked by any data. + +I find the notion of a magic 120MB/s barrier, independent of either +CPU or disk speed, to be pretty dubious to say the least. I would +like to know exactly what the "wide variety" of data points you +haven't shown us are. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Mon Nov 21 10:58:32 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9E677D9FAD + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 10:58:29 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 30986-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 14:58:32 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id 74A56D9E93 + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 10:58:25 -0400 (AST) +Received: from ram.rentec.com (mailhost [192.5.35.66]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jALEvqFu007190 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Mon, 21 Nov 2005 09:57:53 -0500 (EST) +X-Source: non-mednet +Received: from [172.26.132.145] (hoopoe.rentec.com [172.26.132.145]) + by ram.rentec.com (8.13.1/8.12.1) with ESMTP id jALEvLFM025534; + Mon, 21 Nov 2005 09:57:21 -0500 (EST) +Message-ID: <4381E077.80009@rentec.com> +Date: Mon, 21 Nov 2005 09:57:59 -0500 +From: Alan Stange <stange@rentec.com> +Reply-To: stange@rentec.com +Organization: Renaissance Technologies Corp. +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Luke Lonergan <llonergan@greenplum.com> +CC: Greg Stark <gsstark@mit.edu>, Dave Cramer <pg@fastcrypt.com>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA6C187.1425C%llonergan@greenplum.com> +In-Reply-To: <BFA6C187.1425C%llonergan@greenplum.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jALEvqFu007190 at Mon Nov 21 + 09:57:53 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.009 required=5 tests=[AWL=0.009] +X-Spam-Score: 0.009 +X-Spam-Level: +X-Archive-Number: 200511/420 +X-Sequence-Number: 15677 + +Luke Lonergan wrote: +> OK - slower this time: +> We've seen between 110MB/s and 120MB/s on a wide variety of fast CPU +> machines with fast I/O subsystems that can sustain 250MB/s+ using dd, but +> which all are capped at 120MB/s when doing sequential scans with different +> versions of Postgres. +> +Postgresql issues the exact same sequence of read() calls as does dd. +So why is dd so much faster? + +I'd be careful with the dd read of a 16GB file on an 8GB system. Make +sure you umount the file system first, to make sure all of the file is +flushed from memory. Some systems use a freebehind on sequential reads +to avoid flushing memory...and you'd find that 1/2 of your 16GB file is +still in memory. The same point also holds for the writes: when dd +finishes not all the data is on disk. You need to issue a sync() call +to make that happen. Use lmdd to ensure that the data is actually all +written. In other words, I think your dd results are possibly misleading. + +It's trivial to demonstrate: + +$ time dd if=/dev/zero of=/fidb1/bigfile bs=8k count=800000 +800000+0 records in +800000+0 records out + +real 0m13.780s +user 0m0.134s +sys 0m13.510s + +Oops. I just wrote 470MB/s to a file system that has peak write speed +of 200MB/s peak. + +Now, you might say that you wrote a 16GB file on an 8 GB machine so this +isn't an issue. It does make your dd numbers look fast as some of the +data will be unwritten. + + +I'd also suggest running dd on the same files as postgresql. I suspect +you'd find that the layout of the postgresql files isn't that good as +they are grown bit by bit, unlike the file created by simply dd'ing a +large file. + +> Understand my point: It doesn't matter that there is idle or iowait on the +> CPU, the postgres executor is not able to drive the I/O rate for two +> reasons: there is a lot of CPU used for the scan (the 40% you reported) and +> a lack of asynchrony (the iowait time). That means that by speeding up the +> CPU you only reduce the first part, but you don't fix the second and v.v. +> +> With more aggressive readahead, the second problem (the I/O asynchrony) is +> handled better by the Linux kernel and filesystem. That's what we're seeing +> with XFS. + +I think your point doesn't hold up. Every time you make it, I come away +posting another result showing it to be incorrect. + +The point your making doesn't match my experience with *any* storage or +program I've ever used, including postgresql. Your point suggests that +the storage system is idle and that postgresql is broken because it +isn't able to use the resources available...even when the cpu is very +idle. How can that make sense? The issue here is that the storage +system is very active doing reads on the files...which might be somewhat +poorly allocated on disk because postgresql grows the tables bit by bit. + +I had the same readahead in Reiser and in XFS. The XFS performance was +better because XFS does a better job of large file allocation on disk, +thus resulting in many fewer seeks (generated by the file system itself) +to read the files back in. As an example, some file systems like UFS +purposely scatter large files across cylinder groups to avoid forcing +large seeks on small files; one can tune this behavior so that large +files are more tightly allocated. + + + +Of course, because this is engineering, I have another obligatory data +point: This time it's a 4.2GB table using 137,138 32KB pages with +nearly 41 million rows. + +A "select count(1)" on the table completes in 14.6 seconds, for an +average read rate of 320 MB/s. + +One cpu was idle, the other averaged 32% system time and 68 user time +for the 14 second period. This is on a 2.2Ghz Opteron. A faster cpu +would show increased performance as I really am cpu bound finally. + +Postgresql is clearly able to issue the relevant sequential read() +system calls and sink the resulting data without a problem if the file +system is capable of providing the data. It can do this up to a speed +of ~300MB/s on this class of system. Now it should be fairly simple to +tweak the few spots where some excess memory copies are being done and +up this result substantially. I hope postgresql is always using the +libc memcpy as that's going to be a lot faster then some private routine. + +-- Alan + + + +From pgsql-performance-owner@postgresql.org Mon Nov 21 19:07:39 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 85216DB0AC + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 19:07:30 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 88439-07-4 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 23:07:31 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 05766DAAA1 + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 19:07:17 -0400 (AST) +Received: from koolancexeon.g2switchworks.com (mail.g2switchworks.com + [63.87.162.25]) + by svr2.postgresql.org (Postfix) with ESMTP id 11F76F0D54 + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 16:43:59 +0000 (GMT) +Received: mail.g2switchworks.com 10.10.1.8 from 10.10.1.37 10.10.1.37 via HTTP + with MS-WebStorage 6.5.6944 +Received: from state.g2switchworks.com by mail.g2switchworks.com; + 21 Nov 2005 10:43:38 -0600 +Subject: Re: VERY slow after many updates +From: Scott Marlowe <smarlowe@g2switchworks.com> +To: Alex Wang <alex@alexwang.com> +Cc: Csaba Nagy <nagy@ecircle-ag.com>, + postgres performance list <pgsql-performance@postgresql.org> +In-Reply-To: <006b01c5ed04$f640ef70$0200a8c0@alexxp> +References: <002601c5ecdd$503279e0$0200a8c0@alexxp> + <1132398732.10890.480.camel@coppola.muc.ecircle.de> + <005201c5ed01$7f15c310$0200a8c0@alexxp> + <1132402372.10890.487.camel@coppola.muc.ecircle.de> + <006b01c5ed04$f640ef70$0200a8c0@alexxp> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Message-Id: <1132591417.28788.7.camel@state.g2switchworks.com> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) +Date: Mon, 21 Nov 2005 10:43:38 -0600 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/428 +X-Sequence-Number: 15685 + +On Sat, 2005-11-19 at 06:29, Alex Wang wrote: +> Great infomation. I didn't know that update is equal to delete+insert in +> Postgres. I would be more careful on designing the database access method in +> this case. + +Just make sure you have regular vacuums scheduled (or run them from +within your app) and you're fine. + +From pgsql-performance-owner@postgresql.org Mon Nov 21 17:11:41 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D881ADA7ED + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 17:10:46 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 62444-09-3 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 21:10:46 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id B4DACDA82E + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 17:10:37 -0400 (AST) +Received: from mail.Mi8.com (d01gw01.mi8.com [63.240.6.47]) + by svr2.postgresql.org (Postfix) with ESMTP id 6DAC7F0F2E + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 18:07:49 +0000 (GMT) +Received: from 172.16.1.112 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D1)); Mon, 21 Nov 2005 13:07:17 -0500 +X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Mon, 21 Nov + 2005 13:06:49 -0500 +Received: from 208.54.15.129 ([208.54.15.129]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Mon, 21 Nov + 2005 13:06:48 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Mon, 21 Nov 2005 10:06:48 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: stange@rentec.com +Cc: "Greg Stark" <gsstark@mit.edu>, "Dave Cramer" <pg@fastcrypt.com>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-ID: <BFA74CB8.142B5%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXurAsgqp4BO+ENQDCiqsk4EGAnLAAGkvat +In-Reply-To: <4381E077.80009@rentec.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 21 Nov 2005 18:06:49.0402 (UTC) + FILETIME=[57CE99A0:01C5EEC6] +X-WSS-ID: 6F9CD359328245027-18-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.562 required=5 tests=[AWL=0.309, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.562 +X-Spam-Level: * +X-Archive-Number: 200511/425 +X-Sequence-Number: 15682 + +Alan, + +On 11/21/05 6:57 AM, "Alan Stange" <stange@rentec.com> wrote: + +> $ time dd if=/dev/zero of=/fidb1/bigfile bs=8k count=800000 +> 800000+0 records in +> 800000+0 records out +> +> real 0m13.780s +> user 0m0.134s +> sys 0m13.510s +> +> Oops. I just wrote 470MB/s to a file system that has peak write speed +> of 200MB/s peak. + +How much RAM on this machine? + +> Now, you might say that you wrote a 16GB file on an 8 GB machine so this +> isn't an issue. It does make your dd numbers look fast as some of the +> data will be unwritten. + +This simple test, at 2x memory correlates very closely to Bonnie++ numbers +for sequential scan. What's more, we see close to the same peak in practice +with multiple scanners. Furthermore, if you run two of them simultaneously +(on two filesystems), you can also see the I/O limited. + +> I'd also suggest running dd on the same files as postgresql. I suspect +> you'd find that the layout of the postgresql files isn't that good as +> they are grown bit by bit, unlike the file created by simply dd'ing a +> large file. + +Can happen if you're not careful with filesystems (see above). + +There's nothing "wrong" with the dd test. + +> I think your point doesn't hold up. Every time you make it, I come away +> posting another result showing it to be incorrect. + +Prove it - your Reiserfs number was about the same. + +I also posted an XFS number that was substantially higher than 110-120. + +> The point your making doesn't match my experience with *any* storage or +> program I've ever used, including postgresql. Your point suggests that +> the storage system is idle and that postgresql is broken because it +> isn't able to use the resources available...even when the cpu is very +> idle. How can that make sense? The issue here is that the storage +> system is very active doing reads on the files...which might be somewhat +> poorly allocated on disk because postgresql grows the tables bit by bit. + +Then you've made my point - if the problem is contiguity of files on disk, +then larger allocation blocks would help on the CPU side. + +The objective is clear: given a high performance filesystem, how much of the +available bandwidth can Postgres achieve? I think what we're seeing is that +XFS is dramatically improving that objective. + +> I had the same readahead in Reiser and in XFS. The XFS performance was +> better because XFS does a better job of large file allocation on disk, +> thus resulting in many fewer seeks (generated by the file system itself) +> to read the files back in. As an example, some file systems like UFS +> purposely scatter large files across cylinder groups to avoid forcing +> large seeks on small files; one can tune this behavior so that large +> files are more tightly allocated. + +Our other tests have used ext3, reiser and Solaris 10 UFS, so this might +make some sense. + +> Of course, because this is engineering, I have another obligatory data +> point: This time it's a 4.2GB table using 137,138 32KB pages with +> nearly 41 million rows. +> +> A "select count(1)" on the table completes in 14.6 seconds, for an +> average read rate of 320 MB/s. + +So, assuming that the net memory scan rate is about 2GB/s, and two copies +(one from FS cache to buffer cache, one from buffer cache to the agg node), +you have a 700MB/s filesystem with the equivalent of DirectIO (no FS cache) +because you are reading directly from the I/O cache. You got half of that +because the I/O processing in the executor is limited to 320MB/s on that +fast CPU. + +My point is this: if you were to decrease the filesystem speed to say +400MB/s and still use the equivalent of DirectIO, I thinkPostgres would not +deliver 320MB/s, but rather something like 220MB/s due to the +producer/consumer arch of the executor. If you get that part, then we're on +the same track, otherwise we disagree. + +> One cpu was idle, the other averaged 32% system time and 68 user time +> for the 14 second period. This is on a 2.2Ghz Opteron. A faster cpu +> would show increased performance as I really am cpu bound finally. + +Yep, with the equivalent of DirectIO you are. + +- Luke + + + +From pgsql-performance-owner@postgresql.org Mon Nov 21 17:27:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 19227DAEFB + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 17:27:45 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 64347-10-6 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 21:27:45 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 69F7EDAA8D + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 17:27:25 -0400 (AST) +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr2.postgresql.org (Postfix) with ESMTP id B9E02F0F7A + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 18:16:05 +0000 (GMT) +Received: from 172.16.1.112 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Mon, 21 Nov 2005 13:14:33 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Mon, 21 Nov + 2005 13:14:30 -0500 +Received: from 208.54.15.129 ([208.54.15.129]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Mon, 21 Nov + 2005 13:14:29 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Mon, 21 Nov 2005 10:14:29 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Tom Lane" <tgl@sss.pgh.pa.us> +Cc: "Alan Stange" <stange@rentec.com>, + "Greg Stark" <gsstark@mit.edu>, "Dave Cramer" <pg@fastcrypt.com>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-ID: <BFA74E85.142B8%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXuq9ofs/zrYpYQQESePaNtiZGFLgAG4+iw +In-Reply-To: <1611.1132585006@sss.pgh.pa.us> +MIME-Version: 1.0 +X-OriginalArrivalTime: 21 Nov 2005 18:14:30.0315 (UTC) + FILETIME=[6A8857B0:01C5EEC7] +X-WSS-ID: 6F9CD10F2UO356963-04-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=2.18 required=5 tests=[AWL=-0.309, + RCVD_IN_SORBS_WEB=1.236, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 2.18 +X-Spam-Level: ** +X-Archive-Number: 200511/426 +X-Sequence-Number: 15683 + +Tom, + +On 11/21/05 6:56 AM, "Tom Lane" <tgl@sss.pgh.pa.us> wrote: + +> "Luke Lonergan" <llonergan@greenplum.com> writes: +>> OK - slower this time: +> +>> We've seen between 110MB/s and 120MB/s on a wide variety of fast CPU +>> machines with fast I/O subsystems that can sustain 250MB/s+ using dd, but +>> which all are capped at 120MB/s when doing sequential scans with different +>> versions of Postgres. +> +> Luke, sometime it would be nice if you would post your raw evidence +> and let other people do their own analysis. I for one have gotten +> tired of reading sweeping generalizations unbacked by any data. + +This has partly been a challenge to get others to post their results. + +> I find the notion of a magic 120MB/s barrier, independent of either +> CPU or disk speed, to be pretty dubious to say the least. I would +> like to know exactly what the "wide variety" of data points you +> haven't shown us are. + +I'll try to put up some of them, they've occurred over the last 3 years on +various platforms including: +- Dual 3.2GHz Xeon, 2 x Adaptec U320 SCSI attached to 6 x 10K RPM disks, +Linux 2.6.4(?) - 2.6.10 kernel, ext2/3 and Reiser filesystems +120-130MB/s Postgres seq scan rate on 7.4 and 8.0. + +- Dual 1.8 GHz Opteron, 2 x LSI U320 SCSI attached to 6 x 10K RPM disks, +Linux 2.6.10 kernel, ext2/3 and Reiser filesystems +110-120MB/s Postgres seq scan rate on 8.0 + +- Same machine as above running Solaris 10, with UFS filesystem. When I/O +caching is tuned, we reach the same 110-120MB/s Postgres seq scan rate + +- Sam machine as above with 7 x 15K RPM 144GB disks in an external disk +tray, same scan rate + +Only when we got these new SATA systems and tried out XFS with large +readahead have we been able to break past the 120-130MB/s. After Alan's +post, it seems that XFS might be a big part of that. I think we'll test +ext2/3 against XFS on the same machine to find out. + +It may have to wait a week, as many of us are on vacation. + +- Luke + + + +From pgsql-performance-owner@postgresql.org Mon Nov 21 15:01:39 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 009DFD975D + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 15:01:38 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 98299-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 19:01:38 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from stark.xeocode.com (stark.xeocode.com [216.58.44.227]) + by svr1.postgresql.org (Postfix) with ESMTP id 48EFFD9676 + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 15:01:36 -0400 (AST) +Received: from localhost ([127.0.0.1] helo=stark.xeocode.com) + by stark.xeocode.com with smtp (Exim 3.36 #1 (Debian)) + id 1EeGus-0005YC-00; Mon, 21 Nov 2005 14:01:26 -0500 +To: stange@rentec.com +Cc: Luke Lonergan <llonergan@greenplum.com>, Greg Stark <gsstark@mit.edu>, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA6C187.1425C%llonergan@greenplum.com> + <4381E077.80009@rentec.com> +In-Reply-To: <4381E077.80009@rentec.com> +From: Greg Stark <gsstark@mit.edu> +Organization: The Emacs Conspiracy; member since 1992 +Date: 21 Nov 2005 14:01:26 -0500 +Message-ID: <87ek59omex.fsf@stark.xeocode.com> +Lines: 35 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/421 +X-Sequence-Number: 15678 + + +Alan Stange <stange@rentec.com> writes: + +> The point your making doesn't match my experience with *any* storage or program +> I've ever used, including postgresql. Your point suggests that the storage +> system is idle and that postgresql is broken because it isn't able to use the +> resources available...even when the cpu is very idle. How can that make sense? + +Well I think what he's saying is that Postgres is issuing a read, then waiting +for the data to return. Then it does some processing, and goes back to issue +another read. The CPU is idle half the time because Postgres isn't capable of +doing any work while waiting for i/o, and the i/o system is idle half the time +while the CPU intensive part happens. + +(Consider as a pathological example a program that reads 8k then sleeps for +10ms, and loops doing that 1,000 times. Now consider the same program +optimized to read 8M asynchronously and sleep for 10s. By the time it's +finished sleeping it has probably read in all 8M. Whereas the program that +read 8k in little chunks interleaved with small sleeps would probably take +twice as long and appear to be entirely i/o-bound with 50% iowait and 50% +idle.) + +It's a reasonable theory and it's not inconsistent with the results you sent. +But it's not exactly proven either. Nor is it clear how to improve matters. +Adding additional threads to handle the i/o adds an enormous amount of +complexity and creates lots of opportunity for other contention that could +easily eat all of the gains. + +I also fear that heading in that direction could push Postgres even further +from the niche of software that works fine even on low end hardware into the +realm of software that only works on high end hardware. It's already suffering +a bit from that. + +-- +greg + + +From pgsql-performance-owner@postgresql.org Mon Nov 21 15:52:24 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 67466D8EEC + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 15:52:23 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 07241-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 19:52:23 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mx1.surnet.cl (mx1.surnet.cl [216.155.73.180]) + by svr1.postgresql.org (Postfix) with ESMTP id E147CDA246 + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 15:52:19 -0400 (AST) +Received: from unknown (HELO cluster.surnet.cl) ([216.155.73.165]) + by mx1.surnet.cl with ESMTP; 21 Nov 2005 16:53:35 -0300 +X-IronPort-AV: i="3.97,357,1125892800"; + d="scan'208"; a="30194701:sNHT11881021634" +Received: from alvh.no-ip.org (216.155.78.23) by cluster.surnet.cl (7.0.043) + (authenticated as alvherre@surnet.cl) + id 435015970050D685; Mon, 21 Nov 2005 16:51:19 -0300 +Received: by alvh.no-ip.org (Postfix, from userid 1000) + id 460BCCC023C; Mon, 21 Nov 2005 16:51:47 -0300 (CLST) +Date: Mon, 21 Nov 2005 16:51:47 -0300 +From: Alvaro Herrera <alvherre@alvh.no-ip.org> +To: Greg Stark <gsstark@mit.edu> +Cc: stange@rentec.com, Luke Lonergan <llonergan@greenplum.com>, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +Message-ID: <20051121195147.GC26621@surnet.cl> +Mail-Followup-To: Greg Stark <gsstark@mit.edu>, stange@rentec.com, + Luke Lonergan <llonergan@greenplum.com>, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +References: <BFA6C187.1425C%llonergan@greenplum.com> + <4381E077.80009@rentec.com> <87ek59omex.fsf@stark.xeocode.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <87ek59omex.fsf@stark.xeocode.com> +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.782 required=5 tests=[AWL=-0.464, + DNS_FROM_RFC_ABUSE=0.479, DNS_FROM_RFC_POST=1.44, + RCVD_IN_NJABL_PROXY=0.327] +X-Spam-Score: 1.782 +X-Spam-Level: * +X-Archive-Number: 200511/422 +X-Sequence-Number: 15679 + +Greg Stark wrote: + +> I also fear that heading in that direction could push Postgres even further +> from the niche of software that works fine even on low end hardware into the +> realm of software that only works on high end hardware. It's already suffering +> a bit from that. + +What's high end hardware for you? I do development on a Celeron 533 +machine with 448 MB of RAM and I find it to work well (for a "slow" +value of "well", certainly.) If you're talking about embedded hardware, +that's another matter entirely and I don't think we really support the +idea of running Postgres on one of those things. + +There's certainly true in that the memory requirements have increased a +bit, but I don't think it really qualifies as "high end" even on 8.1. + +-- +Alvaro Herrera Developer, http://www.PostgreSQL.org +Jude: I wish humans laid eggs +Ringlord: Why would you want humans to lay eggs? +Jude: So I can eat them + +From pgsql-performance-owner@postgresql.org Mon Nov 21 15:58:38 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0F978DA1EC + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 15:58:38 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 03726-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 19:58:37 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from bfccomputing.com (bfccomputing.com [217.160.248.65]) + by svr1.postgresql.org (Postfix) with ESMTP id 2620DD984A + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 15:58:35 -0400 (AST) +Received: from [10.0.0.202] (68-169-200-61.sbtnvt.adelphia.net + [68.169.200.61]) + by bfccomputing.com (Postfix) with ESMTP + id 0C792E8608; Mon, 21 Nov 2005 14:58:20 -0500 (EST) +In-Reply-To: <87ek59omex.fsf@stark.xeocode.com> +References: <BFA6C187.1425C%llonergan@greenplum.com> + <4381E077.80009@rentec.com> <87ek59omex.fsf@stark.xeocode.com> +Mime-Version: 1.0 (Apple Message framework v623) +Content-Type: text/plain; charset=US-ASCII; format=flowed +Message-Id: <8c110ae5a3902fba586f3353b25fc54f@bfccomputing.com> +Content-Transfer-Encoding: 7bit +Cc: stange@rentec.com, Dave Cramer <pg@fastcrypt.com>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org, + Luke Lonergan <llonergan@greenplum.com> +From: Bill McGonigle <bill@bfccomputing.com> +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Mon, 21 Nov 2005 14:58:18 -0500 +To: Greg Stark <gsstark@mit.edu> +X-Mailer: Apple Mail (2.623) +X-bfccomputing-MailScanner-Information: Please contact the ISP for more + information +X-bfccomputing-MailScanner: Found to be clean +X-bfccomputing-MailScanner-SpamCheck: +X-MailScanner-From: bill@bfccomputing.com +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/423 +X-Sequence-Number: 15680 + +Would it be worth first agreeing on a common set of criteria to +measure? I see many data points going back and forth but not much +agreement on what's worth measuring and how to measure. + +I'm not necessarily trying to herd cats, but it sure would be swell to +have the several knowledgeable minds here come up with something that +could uniformly tested on a range of machines, possibly even integrated +into pg_bench or something. Disagreements on criteria or methodology +should be methodically testable. + +Then I have dreams of a new pg_autotune that would know about these +kinds of system-level settings. + +I haven't been on this list for long, and only using postgres for a +handful of years, so forgive it if this has been hashed out before. + +-Bill +----- +Bill McGonigle, Owner Work: 603.448.4440 +BFC Computing, LLC Home: 603.448.1668 +bill@bfccomputing.com Mobile: 603.252.2606 +http://www.bfccomputing.com/ Pager: 603.442.1833 +Jabber: flowerpt@gmail.com Text: bill+text@bfccomputing.com +Blog: http://blog.bfccomputing.com/ + + +From pgsql-performance-owner@postgresql.org Mon Nov 21 15:59:43 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 324F8DA179 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 15:59:41 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 09401-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 19:59:41 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from vms048pub.verizon.net (vms048pub.verizon.net [206.46.252.48]) + by svr1.postgresql.org (Postfix) with ESMTP id 6B800DA015 + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 15:59:38 -0400 (AST) +Received: from osgiliath.mathom.us ([68.239.91.220]) + by vms048.mailsrvcs.net (Sun Java System Messaging Server 6.2-4.02 + (built Sep + 9 2005)) with ESMTPA id <0IQB00AJJM6NH4N1@vms048.mailsrvcs.net> for + pgsql-performance@postgresql.org; Mon, 21 Nov 2005 13:59:12 -0600 (CST) +Received: from localhost (localhost [127.0.0.1]) + by osgiliath.mathom.us (Postfix) with ESMTP id 71D066005A5 for + <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 14:59:09 -0500 (EST) +Received: from osgiliath.mathom.us ([127.0.0.1]) + by localhost (osgiliath [127.0.0.1]) (amavisd-new, port 10024) + with LMTP id 32155-04 for <pgsql-performance@postgresql.org>; Mon, + 21 Nov 2005 14:59:09 -0500 (EST) +Received: by osgiliath.mathom.us (Postfix, from userid 1000) + id 4C5D96003BD; Mon, 21 Nov 2005 14:59:09 -0500 (EST) +Date: Mon, 21 Nov 2005 14:59:09 -0500 +From: Michael Stone <mstone+postgres@mathom.us> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <87ek59omex.fsf@stark.xeocode.com> +To: pgsql-performance@postgresql.org +Mail-followup-to: pgsql-performance@postgresql.org +Message-id: <20051121195909.GP7330@mathom.us> +MIME-version: 1.0 +Content-type: text/plain; charset=us-ascii; format=flowed +Content-disposition: inline +X-Pgp-Fingerprint: 53 FF 38 00 E7 DD 0A 9C 84 52 84 C5 EE DF 7C 88 +X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at mathom.us +References: <BFA6C187.1425C%llonergan@greenplum.com> + <4381E077.80009@rentec.com> <87ek59omex.fsf@stark.xeocode.com> +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/424 +X-Sequence-Number: 15681 + +On Mon, Nov 21, 2005 at 02:01:26PM -0500, Greg Stark wrote: +>I also fear that heading in that direction could push Postgres even further +>from the niche of software that works fine even on low end hardware into the +>realm of software that only works on high end hardware. It's already suffering +>a bit from that. + +Well, there are are alread a bunch of open source DB's that can handle +the low end. postgres is the closest thing to being able to handle the +high end. + +Mike Stone + +From pgsql-performance-owner@postgresql.org Mon Nov 21 17:54:41 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6278DDA1B6 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 17:54:40 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 72766-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 21:54:41 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id 72F17D975D + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 17:54:35 -0400 (AST) +Received: from wren.rentec.com (wren.rentec.com [192.5.35.106]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jALLrYNC024278 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Mon, 21 Nov 2005 16:53:35 -0500 (EST) +X-Source: non-mednet +Received: from [172.26.132.145] (hoopoe.rentec.com [172.26.132.145]) + by wren.rentec.com (8.13.1/8.12.1) with ESMTP id jALLrdxi029235; + Mon, 21 Nov 2005 16:53:40 -0500 (EST) +Message-ID: <438241E5.2010701@rentec.com> +Date: Mon, 21 Nov 2005 16:53:41 -0500 +From: Alan Stange <stange@rentec.com> +Reply-To: stange@rentec.com +Organization: Renaissance Technologies Corp. +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Luke Lonergan <llonergan@greenplum.com> +CC: Greg Stark <gsstark@mit.edu>, Dave Cramer <pg@fastcrypt.com>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA74CB8.142B5%llonergan@greenplum.com> +In-Reply-To: <BFA74CB8.142B5%llonergan@greenplum.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jALLrYNC024278 at Mon Nov 21 + 16:53:35 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.008 required=5 tests=[AWL=0.008] +X-Spam-Score: 0.008 +X-Spam-Level: +X-Archive-Number: 200511/427 +X-Sequence-Number: 15684 + +Luke, + +it's time to back yourself up with some numbers. You're claiming the +need for a significant rewrite of portions of postgresql and you haven't +done the work to make that case. + +You've apparently made some mistakes on the use of dd to benchmark a +storage system. Use lmdd and umount the file system before the read +and post your results. Using a file 2x the size of memory doesn't work +corectly. You can quote any other numbers you want, but until you use +lmdd correctly you should be ignored. Ideally, since postgresql uses +1GB files, you'll want to use 1GB files for dd as well. + +Luke Lonergan wrote: +> Alan, +> +> On 11/21/05 6:57 AM, "Alan Stange" <stange@rentec.com> wrote: +> +> +>> $ time dd if=/dev/zero of=/fidb1/bigfile bs=8k count=800000 +>> 800000+0 records in +>> 800000+0 records out +>> +>> real 0m13.780s +>> user 0m0.134s +>> sys 0m13.510s +>> +>> Oops. I just wrote 470MB/s to a file system that has peak write speed +>> of 200MB/s peak. +>> +> How much RAM on this machine? +> +Doesn't matter. The result will always be wrong without a call to +sync() or fsync() before the close() if you're trying to measure the +speed of the disk subsystem. Add that sync() and the result will be +correct for any memory size. Just for completeness: Solaris implicitly +calls sync() as part of close. Bonnie used to get this wrong, so +quoting Bonnie isn't any good. Note that on some systems using 2x +memory for these tests is almost OK. For example, Solaris used to have +a hiwater mark that would throttle processes and not allow more than a +few 100K of writes to be outstanding on a file. Linux/XFS clearly +allows a lot of write data to be outstanding. It's best to understand +the tools and know what they do and why they can be wrong than simply +quoting some other tool that makes the same mistakes. + +I find that postgresql is able to achieve about 175MB/s on average from +a system capable of delivering 200MB/s peak and it does this with a lot +of cpu time to spare. Maybe dd can do a little better and deliver +185MB/s. If I were to double the speed of my IO system, I might find +that a single postgresql instance can sink about 300MB/s of data (based +on the last numbers I posted). That's why I have multi-cpu opterons and +more than one query/client as they soak up the remaining IO capacity. + +It is guaranteed that postgresql will hit some threshold of performance +in the future and possible rewrites of some core functionality will be +needed, but no numbers posted here so far have made the case that +postgresql is in trouble now. In the mean time, build balanced +systems with cpus that match the capabilities of the storage subsystems, +use 32KB block sizes for large memory databases that are doing lots of +sequential scans, use file systems tuned for large files, use opterons, etc. + + +As always, one has to post some numbers. Here's an example of how dd +doesn't do what you might expect: + +mite02:~ # lmdd if=internal of=/fidb2/bigfile bs=8k count=2k +16.7772 MB in 0.0235 secs, 714.5931 MB/sec + +mite02:~ # lmdd if=internal of=/fidb2/bigfile bs=8k count=2k sync=1 +16.7772 MB in 0.1410 secs, 118.9696 MB/sec + +Both numbers are "correct". But one measures the kernels ability to +absorb 2000 8KB writes with no guarantee that the data is on disk and +the second measures the disk subsystems ability to write 16MB of data. +dd is equivalent to the first result. You can't use the first type of +result and complain that postgresql is slow. If you wrote 16G of data +on a machine with 8G memory then your dd result is possibly too fast by +a factor of two as 8G of the data might not be on disk yet. We won't +know until you post some results. + +Cheers, + +-- Alan + + +From pgsql-performance-owner@postgresql.org Mon Nov 21 19:44:45 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8ABFEDA810 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 19:44:44 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 94647-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 23:44:45 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw03.mi8.com [63.240.6.42]) + by svr1.postgresql.org (Postfix) with ESMTP id 6B07BDA800 + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 19:44:39 -0400 (AST) +Received: from 172.16.1.112 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D3)); Mon, 21 Nov 2005 18:44:37 -0500 +X-Server-Uuid: E847189C-FC88-4913-9CD4-DE66914F83C0 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Mon, 21 Nov + 2005 18:44:37 -0500 +Received: from 208.54.15.129 ([208.54.15.129]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Mon, 21 Nov + 2005 18:44:36 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Mon, 21 Nov 2005 15:44:35 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: stange@rentec.com +cc: "Greg Stark" <gsstark@mit.edu>, "Dave Cramer" <pg@fastcrypt.com>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-ID: <BFA79BE3.14369%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXu5hMWI9Vj4K+JQRCllSxfoX/kHQAD3P3t +In-Reply-To: <438241E5.2010701@rentec.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 21 Nov 2005 23:44:37.0181 (UTC) + FILETIME=[88583ED0:01C5EEF5] +X-WSS-ID: 6F9C846F19O432430-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=2.283 required=5 tests=[AWL=-0.206, + RCVD_IN_SORBS_WEB=1.236, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 2.283 +X-Spam-Level: ** +X-Archive-Number: 200511/429 +X-Sequence-Number: 15686 + +Alan, + +Unless noted otherwise all results posted are for block device readahead set +to 16M using "blockdev --setra=16384 <block_device>". All are using the +2.6.9-11 Centos 4.1 kernel. + +For those who don't have lmdd, here is a comparison of two results on an +ext2 filesystem: + +============================================================================ +[root@modena1 dbfast1]# time bash -c "(dd if=/dev/zero of=/dbfast1/bigfile +bs=8k count=800000 && sync)" +800000+0 records in +800000+0 records out + +real 0m33.057s +user 0m0.116s +sys 0m13.577s + +[root@modena1 dbfast1]# time lmdd if=/dev/zero of=/dbfast1/bigfile bs=8k +count=800000 sync=1 +6553.6000 MB in 31.2957 secs, 209.4092 MB/sec + +real 0m33.032s +user 0m0.087s +sys 0m13.129s +============================================================================ + +So lmdd with sync=1 is apparently equivalent to a sync after a dd. + +I use 2x memory with dd for the *READ* performance testing, but let's make +sure things are synced on both sides for this set of comparisons. + +First, let's test ext2 versus "ext3, data=ordered", versus reiserfs versus +xfs: + + + + + +From pgsql-performance-owner@postgresql.org Mon Nov 21 19:54:45 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 7C0A8DA55B + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 19:54:44 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 97565-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 21 Nov 2005 23:54:46 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from vms046pub.verizon.net (vms046pub.verizon.net [206.46.252.46]) + by svr1.postgresql.org (Postfix) with ESMTP id B96B6DA51C + for <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 19:54:41 -0400 (AST) +Received: from osgiliath.mathom.us ([68.239.91.220]) + by vms046.mailsrvcs.net (Sun Java System Messaging Server 6.2-4.02 + (built Sep + 9 2005)) with ESMTPA id <0IQB00GNKX385262@vms046.mailsrvcs.net> for + pgsql-performance@postgresql.org; Mon, 21 Nov 2005 17:54:44 -0600 (CST) +Received: from localhost (localhost [127.0.0.1]) + by osgiliath.mathom.us (Postfix) with ESMTP id E5B726003F3 for + <pgsql-performance@postgresql.org>; + Mon, 21 Nov 2005 18:54:44 -0500 (EST) +Received: from osgiliath.mathom.us ([127.0.0.1]) + by localhost (osgiliath [127.0.0.1]) (amavisd-new, port 10024) + with LMTP id 02255-05 for <pgsql-performance@postgresql.org>; Mon, + 21 Nov 2005 18:54:44 -0500 (EST) +Received: by osgiliath.mathom.us (Postfix, from userid 1000) + id C0E606002E7; Mon, 21 Nov 2005 18:54:44 -0500 (EST) +Date: Mon, 21 Nov 2005 18:54:44 -0500 +From: Michael Stone <mstone+postgres@mathom.us> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <BFA74E85.142B8%llonergan@greenplum.com> +To: pgsql-performance@postgresql.org +Mail-followup-to: pgsql-performance@postgresql.org +Message-id: <20051121235444.GR7330@mathom.us> +MIME-version: 1.0 +Content-type: text/plain; charset=us-ascii; format=flowed +Content-disposition: inline +X-Pgp-Fingerprint: 53 FF 38 00 E7 DD 0A 9C 84 52 84 C5 EE DF 7C 88 +X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at mathom.us +References: <1611.1132585006@sss.pgh.pa.us> + <BFA74E85.142B8%llonergan@greenplum.com> +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/430 +X-Sequence-Number: 15687 + +On Mon, Nov 21, 2005 at 10:14:29AM -0800, Luke Lonergan wrote: +>This has partly been a challenge to get others to post their results. + +You'll find that people respond better if you don't play games with +them. + +From pgsql-performance-owner@postgresql.org Tue Nov 22 00:36:19 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D58DEDA246 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; 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Mon, 21 Nov + 2005 23:35:27 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Mon, 21 Nov 2005 20:35:26 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: stange@rentec.com +cc: "Greg Stark" <gsstark@mit.edu>, "Dave Cramer" <pg@fastcrypt.com>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-ID: <BFA7E00E.143DB%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXu5hMWI9Vj4K+JQRCllSxfoX/kHQAOBWQB +In-Reply-To: <438241E5.2010701@rentec.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 22 Nov 2005 04:35:28.0691 (UTC) + FILETIME=[2A415830:01C5EF1E] +X-WSS-ID: 6F9C7FBE19O537613-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=2.335 required=5 tests=[AWL=-0.154, + RCVD_IN_SORBS_WEB=1.236, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 2.335 +X-Spam-Level: ** +X-Archive-Number: 200511/431 +X-Sequence-Number: 15688 + +Alan, + +Looks like Postgres gets sensible scan rate scaling as the filesystem speed +increases, as shown below. I'll drop my 120MB/s observation - perhaps CPUs +got faster since I last tested this. + +The scaling looks like 64% of the I/O subsystem speed is available to the +executor - so as the I/O subsystem increases in scan rate, so does Postgres' +executor scan speed. + +So that leaves the question - why not more than 64% of the I/O scan rate? +And why is it a flat 64% as the I/O subsystem increases in speed from +333-400MB/s? + +- Luke + +================= Results =================== + +Unless noted otherwise all results posted are for block device readahead set +to 16M using "blockdev --setra=16384 <block_device>". All are using the +2.6.9-11 Centos 4.1 kernel. + +For those who don't have lmdd, here is a comparison of two results on an +ext2 filesystem: + +============================================================================ +[root@modena1 dbfast1]# time bash -c "(dd if=/dev/zero of=/dbfast1/bigfile +bs=8k count=800000 && sync)" +800000+0 records in +800000+0 records out + +real 0m33.057s +user 0m0.116s +sys 0m13.577s + +[root@modena1 dbfast1]# time lmdd if=/dev/zero of=/dbfast1/bigfile bs=8k +count=800000 sync=1 +6553.6000 MB in 31.2957 secs, 209.4092 MB/sec + +real 0m33.032s +user 0m0.087s +sys 0m13.129s +============================================================================ + +So lmdd with sync=1 is equivalent to a sync after a dd. + +I use 2x memory with dd for the *READ* performance testing, but let's make +sure things are synced on both write and read for this set of comparisons. + +First, let's test ext2 versus "ext3, data=ordered", versus xfs: + +============================================================================ +16GB write, then read +============================================================================ +----------------------- +ext2: +----------------------- +[root@modena1 dbfast1]# time lmdd if=/dev/zero of=/dbfast1/bigfile bs=8k +count=2000000 sync=1 +16384.0000 MB in 144.2670 secs, 113.5672 MB/sec + +[root@modena1 dbfast1]# time lmdd if=/dbfast1/bigfile of=/dev/null bs=8k +count=2000000 sync=1 +16384.0000 MB in 49.3766 secs, 331.8170 MB/sec + +----------------------- +ext3, data=ordered: +----------------------- +[root@modena1 ~]# time lmdd if=/dev/zero of=/dbfast1/bigfile bs=8k +count=2000000 sync=1 +16384.0000 MB in 137.1607 secs, 119.4511 MB/sec + +[root@modena1 ~]# time lmdd if=/dbfast1/bigfile of=/dev/null bs=8k +count=2000000 sync=1 +16384.0000 MB in 48.7398 secs, 336.1527 MB/sec + +----------------------- +xfs: +----------------------- +[root@modena1 ~]# time lmdd if=/dev/zero of=/dbfast1/bigfile bs=8k +count=2000000 sync=1 +16384.0000 MB in 52.6141 secs, 311.3994 MB/sec + +[root@modena1 ~]# time lmdd if=/dbfast1/bigfile of=/dev/null bs=8k +count=2000000 sync=1 +16384.0000 MB in 40.2807 secs, 406.7453 MB/sec +============================================================================ + +I'm liking xfs! Something about the way files are layed out, as Alan +suggested seems to dramatically improve write performance and perhaps +consequently the read also improves. There doesn't seem to be a difference +between ext3 and ext2, as expected. + +Now on to the Postgres 8 tests. We'll do a 16GB table size to ensure that +we aren't reading from the read cache. I'll write this file through +Postgres COPY to be sure that the file layout is as Postgres creates it. The +alternative would be to use COPY once, then tar/untar onto different +filesystems, but that may not duplicate the real world results. + +These tests will use Bizgres 0_8_1, which is an augmented 8.0.3. None of +the augmentations act to improve the executor I/O though, so for these +purposes it should be the same as 8.0.3. + +============================================================================ +26GB of DBT-3 data from the lineitem table +============================================================================ +llonergan=# select relpages from pg_class where relname='lineitem'; + relpages +---------- + 3159138 +(1 row) + +3159138*8192/1000000 +25879 Million Bytes, or 25.9GB + +----------------------- +xfs: +----------------------- +llonergan=# \timing +Timing is on. +llonergan=# select count(1) from lineitem; + count +----------- + 119994608 +(1 row) + +Time: 394908.501 ms +llonergan=# select count(1) from lineitem; + count +----------- + 119994608 +(1 row) + +Time: 99425.223 ms +llonergan=# select count(1) from lineitem; + count +----------- + 119994608 +(1 row) + +Time: 99187.205 ms + +----------------------- +ext2: +----------------------- +llonergan=# select relpages from pg_class where relname='lineitem'; + relpages +---------- + 3159138 +(1 row) + +llonergan=# \timing +Timing is on. +llonergan=# select count(1) from lineitem; + count +----------- + 119994608 +(1 row) + +Time: 395286.475 ms +llonergan=# select count(1) from lineitem; + count +----------- + 119994608 +(1 row) + +Time: 195756.381 ms +llonergan=# select count(1) from lineitem; + count +----------- + 119994608 +(1 row) + +Time: 122822.090 ms +============================================================================ +Analysis of Postgres 8.0.3 results +============================================================================ + ext2 xfs +Write Speed 114 311 +Read Speed 332 407 +Postgres Seq Scan Speed 212 263 +Scan % of lmdd Read Speed 63.9% 64.6% + +Well - looks like we get linear scaling with disk/file subsystem speedup. + +- Luke + + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 01:10:32 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5E3CCDA994 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 01:10:31 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 80198-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 05:10:29 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from linda-1.paradise.net.nz (bm-1a.paradise.net.nz + [203.96.152.180]) + by svr1.postgresql.org (Postfix) with ESMTP id 75114DA987 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 01:10:28 -0400 (AST) +Received: from smtp-3.paradise.net.nz (tclsnelbe2-src-nat-1 [203.96.152.177]) + by linda-1.paradise.net.nz (Paradise.net.nz) + with ESMTP id <0IQC00EW2BPFBP@linda-1.paradise.net.nz> for + pgsql-performance@postgresql.org; Tue, 22 Nov 2005 18:10:28 +1300 (NZDT) +Received: from [192.168.1.11] (218-101-28-59.dsl.clear.net.nz [218.101.28.59]) + by smtp-3.paradise.net.nz (Postfix) with ESMTP id 2E104DB4AD3; Tue, + 22 Nov 2005 18:10:27 +1300 (NZDT) +Date: Tue, 22 Nov 2005 18:10:24 +1300 +From: Mark Kirkwood <markir@paradise.net.nz> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <BFA7E00E.143DB%llonergan@greenplum.com> +To: Luke Lonergan <llonergan@greenplum.com> +Cc: stange@rentec.com, Greg Stark <gsstark@mit.edu>, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Message-id: <4382A840.3030401@paradise.net.nz> +MIME-version: 1.0 +Content-type: multipart/mixed; boundary=------------030902030501050304090108 +X-Accept-Language: en-us, en +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20051106) +References: <BFA7E00E.143DB%llonergan@greenplum.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.222 required=5 tests=[AWL=0.222] +X-Spam-Score: 0.222 +X-Spam-Level: +X-Archive-Number: 200511/432 +X-Sequence-Number: 15689 + +This is a multi-part message in MIME format. +--------------030902030501050304090108 +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit + +Luke Lonergan wrote: + +> So that leaves the question - why not more than 64% of the I/O scan rate? +> And why is it a flat 64% as the I/O subsystem increases in speed from +> 333-400MB/s? +> + +It might be interesting to see what effect reducing the cpu consumption + entailed by the count aggregation has - by (say) writing a little bit +of code to heap scan the desired relation (sample attached). + +Cheers + +Mark + + + + + +--------------030902030501050304090108 +Content-Type: text/plain; + name="fastcount.c" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline; + filename="fastcount.c" + +/* + * fastcount.c + * + * Do a count that uses considerably less CPU time than an aggregate. + */ + +#include "postgres.h" + +#include "funcapi.h" +#include "access/heapam.h" +#include "catalog/namespace.h" +#include "utils/builtins.h" + + +extern Datum fastcount(PG_FUNCTION_ARGS); + + +PG_FUNCTION_INFO_V1(fastcount); +Datum +fastcount(PG_FUNCTION_ARGS) +{ + text *relname = PG_GETARG_TEXT_P(0); + RangeVar *relrv; + Relation rel; + HeapScanDesc scan; + HeapTuple tuple; + int64 result = 0; + + /* Use the name to get a suitable range variable and open the relation. */ + relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname)); + rel = heap_openrv(relrv, AccessShareLock); + + /* Start a heap scan on the relation. */ + scan = heap_beginscan(rel, SnapshotNow, 0, NULL); + while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL) + { + result++; + } + + /* End the scan and close up the relation. */ + heap_endscan(scan); + heap_close(rel, AccessShareLock); + + + PG_RETURN_INT64(result); +} + +--------------030902030501050304090108-- + +From pgsql-performance-owner@postgresql.org Tue Nov 22 03:20:55 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id E3F7BDA7DE + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 03:20:52 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 07741-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 07:20:52 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id 0E17EDA269 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 03:20:50 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id CC1C431059; Tue, 22 Nov 2005 08:20:50 +0100 (MET) +From: "Qingqing Zhou" <zhouqq@cs.toronto.edu> +X-Newsgroups: pgsql.performance +Subject: Re: weird performances problem +Date: Tue, 22 Nov 2005 02:21:12 -0500 +Organization: Hub.Org Networking Services +Lines: 39 +Message-ID: <dlugsf$25o5$1@news.hub.org> +References: <437CC21D.8070402@openwide.fr> +X-Complaints-To: usenet@news.hub.org +X-Priority: 3 +X-MSMail-Priority: Normal +X-Newsreader: Microsoft Outlook Express 6.00.2900.2180 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 +X-RFC2646: Format=Flowed; Original +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.086 required=5 tests=[AWL=0.086] +X-Spam-Score: 0.086 +X-Spam-Level: +X-Archive-Number: 200511/433 +X-Sequence-Number: 15690 + + +"Guillaume Smet" <guillaume.smet@openwide.fr> wrote +> [root@bd root]# iostat 10 +> +> Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn +> sda 7.20 0.00 92.00 0 920 +> sda1 0.00 0.00 0.00 0 0 +> sda2 6.40 0.00 78.40 0 784 +> sda3 0.00 0.00 0.00 0 0 +> sda4 0.00 0.00 0.00 0 0 +> sda5 0.00 0.00 0.00 0 0 +> sda6 0.80 0.00 13.60 0 136 +> sdb 5.00 0.00 165.60 0 1656 +> sdb1 5.00 0.00 165.60 0 1656 +> +> Nested Loop (cost=0.00..13.52 rows=2 width=1119) (actual +> time=155.286..155.305 rows=1 loops=1) +> -> Index Scan using pk_newslang on newslang nl (cost=0.00..3.87 rows=1 +> width=1004) (actual time=44.575..44.579 rows=1 loops=1) +> Index Cond: (((codelang)::text = 'FRA'::text) AND (3498704 = +> numnews)) +> -> Nested Loop Left Join (cost=0.00..9.61 rows=2 width=119) (actual +> time=110.648..110.660 rows=1 loops=1) +> -> Index Scan using pk_news on news n (cost=0.00..3.31 rows=2 +> width=98) (actual time=0.169..0.174 rows=1 loops=1) +> Index Cond: (numnews = 3498704) +> -> Index Scan using pk_photo on photo p (cost=0.00..3.14 rows=1 +> width=25) (actual time=110.451..110.454 rows=1 loops=1) +> Index Cond: (p.numphoto = "outer".numphoto) +> Total runtime: 155.514 ms +> + +Someone is doing a massive *write* at this time, which makes your query +*read* quite slow. Can you find out which process is doing write? + +Regards, +Qingqing + + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 05:49:25 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 346D4DADF9 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 05:49:25 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 61542-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 09:49:26 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from soufre.accelance.net (soufre.accelance.net [213.162.48.15]) + by svr1.postgresql.org (Postfix) with ESMTP id B3B83DACD9 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 05:49:21 -0400 (AST) +Received: from [213.162.49.207] (gs.team.openwide.fr [213.162.49.207]) + (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) + (No client certificate requested) + by soufre.accelance.net (Postfix) with ESMTP id E8A4D5E1C; + Tue, 22 Nov 2005 10:49:22 +0100 (CET) +Message-ID: <4382E9A2.5080102@openwide.fr> +Date: Tue, 22 Nov 2005 10:49:22 +0100 +From: Guillaume Smet <guillaume.smet@openwide.fr> +User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc3 (X11/20050929) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Andrew Sullivan <ajs@crankycanuck.ca> +CC: pgsql-performance@postgresql.org +Subject: Re: weird performances problem +References: <437CC21D.8070402@openwide.fr> + <20051117221314.GC26696@phlogiston.dyndns.org> + <437D13AA.4010309@openwide.fr> + <20051118161312.GC28967@phlogiston.dyndns.org> +In-Reply-To: <20051118161312.GC28967@phlogiston.dyndns.org> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/434 +X-Sequence-Number: 15691 + +Andrew, + +> I would be very suspicious of that much memory for sort. Please see +> the docs for what that does. That is the amount that _each sort_ can +> allocate before spilling to disk. +> If some set of your users are +> causing complicated queries with, say, four sorts apiece, then each +> user is potentially allocating 4x that much memory. That's going to +> wreak havoc on your disk buffers (which are tricky to monitor on most +> systems, and impossible on some). + +Yes, we have effectively complicated queries. That's why we put the +sort_mem so high. I'll see if we can put it lower for the next few days +to see if it improves our performances. + +Thanks for your help. + +-- +Guillaume + +From pgsql-performance-owner@postgresql.org Tue Nov 22 05:56:42 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 2A27FD7DB4 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 05:56:42 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 69385-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 09:56:43 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from soufre.accelance.net (soufre.accelance.net [213.162.48.15]) + by svr1.postgresql.org (Postfix) with ESMTP id 6B657D6833 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 05:56:39 -0400 (AST) +Received: from [213.162.49.207] (gs.team.openwide.fr [213.162.49.207]) + (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) + (No client certificate requested) + by soufre.accelance.net (Postfix) with ESMTP id 735955D39; + Tue, 22 Nov 2005 10:56:41 +0100 (CET) +Message-ID: <4382EB58.3020804@openwide.fr> +Date: Tue, 22 Nov 2005 10:56:40 +0100 +From: Guillaume Smet <guillaume.smet@openwide.fr> +User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc3 (X11/20050929) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Qingqing Zhou <zhouqq@cs.toronto.edu> +CC: pgsql-performance@postgresql.org +Subject: Re: weird performances problem +References: <437CC21D.8070402@openwide.fr> <dlugsf$25o5$1@news.hub.org> +In-Reply-To: <dlugsf$25o5$1@news.hub.org> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/435 +X-Sequence-Number: 15692 + +Qingqing Zhou wrote: +> Someone is doing a massive *write* at this time, which makes your query +> *read* quite slow. Can you find out which process is doing write? + +Indexes should be in memory so I don't expect a massive write to slow +down the select queries. sdb is the RAID10 array dedicated to our data +so the postgresql process is the only one to write on it. I'll check +which write queries are running because there should really be a few +updates/inserts on our db during the day. + +On a four days log analysis, I have the following: +SELECT 403,964 +INSERT 574 +UPDATE 393 +DELETE 26 +So it's not really normal to have a massive write during the day. + +Thanks for your help + +-- +Guillaume + +From pgsql-performance-owner@postgresql.org Tue Nov 22 08:53:53 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8E0CEDB00C + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 08:53:52 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 26433-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 12:53:54 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtpauth07.mail.atl.earthlink.net + (smtpauth07.mail.atl.earthlink.net [209.86.89.67]) + by svr1.postgresql.org (Postfix) with ESMTP id 63538DB00A + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 08:53:49 -0400 (AST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; + d=earthlink.net; + b=pMhVfQxkvuym0UWtg42XkhhcOCtc6pqsdfgse4EnLbEE3ZkKf+1oCg1SA4Ob/fb2; + h=Received:Message-Id:X-Mailer:Date:To:From:Subject:In-Reply-To:References:Mime-Version:Content-Type:X-ELNK-Trace:X-Originating-IP; +Received: from [71.243.20.20] (helo=ron-6d52adff2a6.earthlink.net) + by smtpauth07.mail.atl.earthlink.net with asmtp (Exim 4.34) + id 1EeXeh-0005Ec-Ka; Tue, 22 Nov 2005 07:53:51 -0500 +Message-Id: <6.2.5.6.0.20051122074454.040fae60@earthlink.net> +X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6 +Date: Tue, 22 Nov 2005 07:53:46 -0500 +To: Guillaume Smet <guillaume.smet@openwide.fr>, + pgsql-performance@postgresql.org +From: Ron <rjpeace@earthlink.net> +Subject: Re: weird performances problem +In-Reply-To: <4382EB58.3020804@openwide.fr> +References: <437CC21D.8070402@openwide.fr> <dlugsf$25o5$1@news.hub.org> + <4382EB58.3020804@openwide.fr> +Mime-Version: 1.0 +Content-Type: text/plain; charset="us-ascii"; format=flowed +X-ELNK-Trace: + acd68a6551193be5d780f4a490ca69563f9fea00a6dd62bca2db04e142f8bedb9902a761ab5391f8350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c +X-Originating-IP: 71.243.20.20 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.359 required=5 tests=[AWL=-0.120, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.359 +X-Spam-Level: +X-Archive-Number: 200511/436 +X-Sequence-Number: 15693 + +If I understand your HW config correctly, all of the pg stuff is on +the same RAID 10 set? + +If so, give WAL its own dedicated RAID 10 set. This looks like the +old problem of everything stalling while WAL is being committed to HD. + +This concept works for other tables as well. If you have a tables +that both want services at the same time, disk arm contention will +drag performance into the floor when they are on the same HW set. + +Profile your HD access and put tables that want to be accessed at the +same time on different HD sets. Even if you have to buy more HW to do it. + +Ron + + +At 04:56 AM 11/22/2005, Guillaume Smet wrote: +>Qingqing Zhou wrote: +>>Someone is doing a massive *write* at this time, which makes your +>>query *read* quite slow. Can you find out which process is doing write? +> +>Indexes should be in memory so I don't expect a massive write to +>slow down the select queries. sdb is the RAID10 array dedicated to +>our data so the postgresql process is the only one to write on it. +>I'll check which write queries are running because there should +>really be a few updates/inserts on our db during the day. +> +>On a four days log analysis, I have the following: +>SELECT 403,964 +>INSERT 574 +>UPDATE 393 +>DELETE 26 +>So it's not really normal to have a massive write during the day. +> +>Thanks for your help +> +>-- +>Guillaume +> +>---------------------------(end of broadcast)--------------------------- +>TIP 2: Don't 'kill -9' the postmaster + + + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 09:29:34 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 56814DAFFF + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 09:29:33 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 34544-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 13:29:35 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 7713DDAFE3 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 09:29:30 -0400 (AST) +Received: from europa.cosmos.opusvl.com (europa.cosmos.opusvl.com + [213.106.249.125]) + by svr2.postgresql.org (Postfix) with ESMTP id 3AC91F0BA2 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 13:29:34 +0000 (GMT) +Received: from localhost.localdomain ([127.0.0.1]) + by europa.cosmos.opusvl.com with esmtp (Exim 4.30) + id 1EeYDB-0001vy-ET; Tue, 22 Nov 2005 13:29:29 +0000 +Message-ID: <43831D39.4030407@opusvl.com> +Date: Tue, 22 Nov 2005 13:29:29 +0000 +From: Rich Doughty <rich@opusvl.com> +Organization: Opus VL +User-Agent: Mozilla Thunderbird 1.0.2 (X11/20050317) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Tom Lane <tgl@sss.pgh.pa.us> +Cc: Pgsql-Performance <pgsql-performance@postgresql.org> +Subject: Re: Strange query plan invloving a view +References: <437BD7A2.608@opusvl.com> <29531.1132250815@sss.pgh.pa.us> +In-Reply-To: <29531.1132250815@sss.pgh.pa.us> +Content-Type: text/plain; charset=UTF-8; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/437 +X-Sequence-Number: 15694 + +Tom Lane wrote: +> Rich Doughty <rich@opusvl.com> writes: +> +>>However, the following query (which i believe should be equivalent) +> +> +>>SELECT * +>>FROM +>> tokens.ta_tokenhist h INNER JOIN +>> tokens.ta_tokens t ON h.token_id = t.token_id LEFT JOIN +>> tokens.ta_tokenhist i ON t.token_id = i.token_id AND +>> i.status = 'issued' LEFT JOIN +>> tokens.ta_tokenhist s ON t.token_id = s.token_id AND +>> s.status = 'sold' LEFT JOIN +>> tokens.ta_tokenhist r ON t.token_id = r.token_id AND +>> r.status = 'redeemed' +>>WHERE +>> h.sarreport_id = 9 +>>; +> +> +> No, that's not equivalent at all, because the implicit parenthesization +> is left-to-right; therefore you've injected the constraint to a few rows +> of ta_tokenhist (and therefore only a few rows of ta_tokens) into the +> bottom of the LEFT JOIN stack. In the other case the constraint is at +> the wrong end of the join stack, and so the full view output gets formed +> before anything gets thrown away. +> +> Some day the Postgres planner will probably be smart enough to rearrange +> the join order despite the presence of outer joins ... but today is not +> that day. + +thanks for the reply. + +is there any way i can achieve what i need to by using views, or should i +just use a normal query? i'd prefer to use a view but i just can't get round +the performance hit. + +-- + + - Rich Doughty + +From pgsql-performance-owner@postgresql.org Tue Nov 22 10:29:44 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A109CDAFD1 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 10:29:43 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 49335-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 14:29:42 +0000 (GMT) +X-Greylist: delayed 00:06:37.484839 by SQLgrey- +Received: from zeus.infor.pl (62-29-138-135.infor.pl [62.29.138.135]) + by svr1.postgresql.org (Postfix) with ESMTP id B57BDDAFBD + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 10:29:36 -0400 (AST) +Received: (qmail 2655 invoked by uid 0); 22 Nov 2005 14:23:01 -0000 +Received: from 127.0.0.1 by zeus (envelope-from <marek.dabrowski@infor.pl>, + uid 501) with qmail-scanner-1.23 + (avp: 5.0.2.0. spamassassin: 2.63. Clear:RC:1(127.0.0.1):. + Processed in 1.799493 secs); 22 lis 2005 14:23:01 -0000 +Received: from unknown (HELO [192.168.1.7]) ([127.0.0.1]) + (envelope-sender <marek.dabrowski@infor.pl>) + by zeus.infor.pl (qmail-ldap-1.03) with SMTP + for <pgsql-performance@postgresql.org>; 22 Nov 2005 14:22:59 -0000 +Message-ID: <438329C3.9060603@infor.pl> +Date: Tue, 22 Nov 2005 15:22:59 +0100 +From: Marek Dabrowski <marek.dabrowski@infor.pl> +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20050716) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Pgsql-Performance <pgsql-performance@postgresql.org> +Subject: System queue +Content-Type: text/plain; charset=ISO-8859-2; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/440 +X-Sequence-Number: 15697 + +Hello + +On my serwer Linux Fedora, HP DL360G3 with 2x3.06 GHz 4GB RAM working +postgresql 7.4.6. Cpu utilization is about 40-50% but system process +queue is long - about 6 task. Do you have nay sugestion/solution? + +Regards +Marek + +From pgsql-performance-owner@postgresql.org Tue Nov 22 10:27:31 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 667F8DAFCD + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 10:27:30 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 50067-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 14:27:33 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id 1329ADAFA5 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 10:27:26 -0400 (AST) +Received: from wren.rentec.com (wren.rentec.com [192.5.35.106]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jAMEQVuS028174 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Tue, 22 Nov 2005 09:26:33 -0500 (EST) +X-Source: non-mednet +Received: from [172.26.132.145] (hoopoe.rentec.com [172.26.132.145]) + by wren.rentec.com (8.13.1/8.12.1) with ESMTP id jAMEQagR006112; + Tue, 22 Nov 2005 09:26:36 -0500 (EST) +Message-ID: <43832A9E.3030801@rentec.com> +Date: Tue, 22 Nov 2005 09:26:38 -0500 +From: Alan Stange <stange@rentec.com> +Reply-To: stange@rentec.com +Organization: Renaissance Technologies Corp. +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Luke Lonergan <llonergan@greenplum.com> +CC: Greg Stark <gsstark@mit.edu>, Dave Cramer <pg@fastcrypt.com>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA7E00E.143DB%llonergan@greenplum.com> +In-Reply-To: <BFA7E00E.143DB%llonergan@greenplum.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jAMEQVuS028174 at Tue Nov 22 + 09:26:33 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.008 required=5 tests=[AWL=0.008] +X-Spam-Score: 0.008 +X-Spam-Level: +X-Archive-Number: 200511/439 +X-Sequence-Number: 15696 + +Luke, + +- XFS will probably generate better data rates with larger files. You +really need to use the same file size as does postgresql. Why compare +the speed to reading a 16G file and the speed to reading a 1G file. +They won't be the same. If need be, write some code that does the test +or modify lmdd to read a sequence of 1G files. Will this make a +difference? You don't know until you do it. Any time you cross a +couple of 2^ powers in computing, you should expect some differences. + +- you did umount the file system before reading the 16G file back in? +Because if you didn't then your read numbers are possibly garbage. +When the read began, 8G of the file was in memory. You'd be very naive +to think that somehow the read of the first 8GB somehow flushed that +cached data out of memory. After all, why would the kernel flush pages +from file X when you're in the middle of a sequential read of...file +X? I'm not sure how Linux handles this, but Solaris would've found the +8G still in memory. + +- What was the hardware and disk configuration on which these numbers +were generated? For example, if you have a U320 controller, how did +the read rate become larger than 320MB/s? + +- how did the results change from before? Just posting the new results +is misleading given all the boasting we've had to read about your past +results. + +- there are two results below for writing to ext2: one at 209 MB/s and +one at 113MB/s. Why are they different? + +- what was the cpu usage during these tests? We see postgresql doing +200+MB/s of IO. You've claimed many times that the machine would be +compute bound at lower IO rates, so how much idle time does the cpu +still have? + +- You wrote: "We'll do a 16GB table size to ensure that we aren't +reading from the read cache. " Do you really believe that?? You have +to umount the file system before each test to ensure you're really +measuring the disk IO rate. If I'm reading your results correctly, it +looks like you have three results for ext and xfs, each of which is +faster than the prior one. If I'm reading this correctly, then it looks +like one is clearly reading from the read cache. + +- Gee, it's so nice of you to drop your 120MB/s observation. I guess my +reading at 300MB/s wasn't convincing enough. Yeah, I think it was the +cpus too... + +- I wouldn't focus on the flat 64% of the data rate number. It'll +probably be different on other systems. + +I'm all for testing and testing. It seems you still cut a corner +without umounting the file system first. Maybe I'm a little too old +school on this, but I wouldn't spend a dime until you've done the +measurements correctly. + +Good Luck. + +-- Alan + + + +Luke Lonergan wrote: +> Alan, +> +> Looks like Postgres gets sensible scan rate scaling as the filesystem speed +> increases, as shown below. I'll drop my 120MB/s observation - perhaps CPUs +> got faster since I last tested this. +> +> The scaling looks like 64% of the I/O subsystem speed is available to the +> executor - so as the I/O subsystem increases in scan rate, so does Postgres' +> executor scan speed. +> +> So that leaves the question - why not more than 64% of the I/O scan rate? +> And why is it a flat 64% as the I/O subsystem increases in speed from +> 333-400MB/s? +> +> - Luke +> +> ================= Results =================== +> +> Unless noted otherwise all results posted are for block device readahead set +> to 16M using "blockdev --setra=16384 <block_device>". All are using the +> 2.6.9-11 Centos 4.1 kernel. +> +> For those who don't have lmdd, here is a comparison of two results on an +> ext2 filesystem: +> +> ============================================================================ +> [root@modena1 dbfast1]# time bash -c "(dd if=/dev/zero of=/dbfast1/bigfile +> bs=8k count=800000 && sync)" +> 800000+0 records in +> 800000+0 records out +> +> real 0m33.057s +> user 0m0.116s +> sys 0m13.577s +> +> [root@modena1 dbfast1]# time lmdd if=/dev/zero of=/dbfast1/bigfile bs=8k +> count=800000 sync=1 +> 6553.6000 MB in 31.2957 secs, 209.4092 MB/sec +> +> real 0m33.032s +> user 0m0.087s +> sys 0m13.129s +> ============================================================================ +> +> So lmdd with sync=1 is equivalent to a sync after a dd. +> +> I use 2x memory with dd for the *READ* performance testing, but let's make +> sure things are synced on both write and read for this set of comparisons. +> +> First, let's test ext2 versus "ext3, data=ordered", versus xfs: +> +> ============================================================================ +> 16GB write, then read +> ============================================================================ +> ----------------------- +> ext2: +> ----------------------- +> [root@modena1 dbfast1]# time lmdd if=/dev/zero of=/dbfast1/bigfile bs=8k +> count=2000000 sync=1 +> 16384.0000 MB in 144.2670 secs, 113.5672 MB/sec +> +> [root@modena1 dbfast1]# time lmdd if=/dbfast1/bigfile of=/dev/null bs=8k +> count=2000000 sync=1 +> 16384.0000 MB in 49.3766 secs, 331.8170 MB/sec +> +> ----------------------- +> ext3, data=ordered: +> ----------------------- +> [root@modena1 ~]# time lmdd if=/dev/zero of=/dbfast1/bigfile bs=8k +> count=2000000 sync=1 +> 16384.0000 MB in 137.1607 secs, 119.4511 MB/sec +> +> [root@modena1 ~]# time lmdd if=/dbfast1/bigfile of=/dev/null bs=8k +> count=2000000 sync=1 +> 16384.0000 MB in 48.7398 secs, 336.1527 MB/sec +> +> ----------------------- +> xfs: +> ----------------------- +> [root@modena1 ~]# time lmdd if=/dev/zero of=/dbfast1/bigfile bs=8k +> count=2000000 sync=1 +> 16384.0000 MB in 52.6141 secs, 311.3994 MB/sec +> +> [root@modena1 ~]# time lmdd if=/dbfast1/bigfile of=/dev/null bs=8k +> count=2000000 sync=1 +> 16384.0000 MB in 40.2807 secs, 406.7453 MB/sec +> ============================================================================ +> +> I'm liking xfs! Something about the way files are layed out, as Alan +> suggested seems to dramatically improve write performance and perhaps +> consequently the read also improves. There doesn't seem to be a difference +> between ext3 and ext2, as expected. +> +> Now on to the Postgres 8 tests. We'll do a 16GB table size to ensure that +> we aren't reading from the read cache. I'll write this file through +> Postgres COPY to be sure that the file layout is as Postgres creates it. The +> alternative would be to use COPY once, then tar/untar onto different +> filesystems, but that may not duplicate the real world results. +> +> These tests will use Bizgres 0_8_1, which is an augmented 8.0.3. None of +> the augmentations act to improve the executor I/O though, so for these +> purposes it should be the same as 8.0.3. +> +> ============================================================================ +> 26GB of DBT-3 data from the lineitem table +> ============================================================================ +> llonergan=# select relpages from pg_class where relname='lineitem'; +> relpages +> ---------- +> 3159138 +> (1 row) +> +> 3159138*8192/1000000 +> 25879 Million Bytes, or 25.9GB +> +> ----------------------- +> xfs: +> ----------------------- +> llonergan=# \timing +> Timing is on. +> llonergan=# select count(1) from lineitem; +> count +> ----------- +> 119994608 +> (1 row) +> +> Time: 394908.501 ms +> llonergan=# select count(1) from lineitem; +> count +> ----------- +> 119994608 +> (1 row) +> +> Time: 99425.223 ms +> llonergan=# select count(1) from lineitem; +> count +> ----------- +> 119994608 +> (1 row) +> +> Time: 99187.205 ms +> +> ----------------------- +> ext2: +> ----------------------- +> llonergan=# select relpages from pg_class where relname='lineitem'; +> relpages +> ---------- +> 3159138 +> (1 row) +> +> llonergan=# \timing +> Timing is on. +> llonergan=# select count(1) from lineitem; +> count +> ----------- +> 119994608 +> (1 row) +> +> Time: 395286.475 ms +> llonergan=# select count(1) from lineitem; +> count +> ----------- +> 119994608 +> (1 row) +> +> Time: 195756.381 ms +> llonergan=# select count(1) from lineitem; +> count +> ----------- +> 119994608 +> (1 row) +> +> Time: 122822.090 ms +> ============================================================================ +> Analysis of Postgres 8.0.3 results +> ============================================================================ +> ext2 xfs +> Write Speed 114 311 +> Read Speed 332 407 +> Postgres Seq Scan Speed 212 263 +> Scan % of lmdd Read Speed 63.9% 64.6% +> +> Well - looks like we get linear scaling with disk/file subsystem speedup. +> +> - Luke +> +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 4: Have you searched our list archives? +> +> http://archives.postgresql.org +> + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 10:26:45 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 95371DAFCD + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 10:26:44 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 49335-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 14:26:47 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from soufre.accelance.net (soufre.accelance.net [213.162.48.15]) + by svr1.postgresql.org (Postfix) with ESMTP id 3A868DAFA5 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 10:26:40 -0400 (AST) +Received: from [213.162.49.207] (gs.team.openwide.fr [213.162.49.207]) + (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) + (No client certificate requested) + by soufre.accelance.net (Postfix) with ESMTP id 420555CEC; + Tue, 22 Nov 2005 15:26:44 +0100 (CET) +Message-ID: <43832AA3.6080606@openwide.fr> +Date: Tue, 22 Nov 2005 15:26:43 +0100 +From: Guillaume Smet <guillaume.smet@openwide.fr> +User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc3 (X11/20050929) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Ron <rjpeace@earthlink.net> +CC: pgsql-performance@postgresql.org +Subject: Re: weird performances problem +References: <437CC21D.8070402@openwide.fr> <dlugsf$25o5$1@news.hub.org> + <4382EB58.3020804@openwide.fr> + <6.2.5.6.0.20051122074454.040fae60@earthlink.net> +In-Reply-To: <6.2.5.6.0.20051122074454.040fae60@earthlink.net> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/438 +X-Sequence-Number: 15695 + +Ron wrote: +> If I understand your HW config correctly, all of the pg stuff is on the +> same RAID 10 set? + +No, the system and the WAL are on a RAID 1 array and the data on their +own RAID 10 array. +As I said earlier, there's only a few writes in the database so I'm not +really sure the WAL can be a limitation: IIRC, it's only used for writes +isn't it? +Don't you think we should have some io wait if the database was waiting +for the WAL? We _never_ have any io wait on this server but our CPUs are +still 30-40% idle. + +A typical top we have on this server is: + 15:22:39 up 24 days, 13:30, 2 users, load average: 3.86, 3.96, 3.99 +156 processes: 153 sleeping, 3 running, 0 zombie, 0 stopped +CPU states: cpu user nice system irq softirq iowait idle + total 50.6% 0.0% 4.7% 0.0% 0.6% 0.0% 43.8% + cpu00 47.4% 0.0% 3.1% 0.3% 1.5% 0.0% 47.4% + cpu01 43.7% 0.0% 3.7% 0.0% 0.5% 0.0% 51.8% + cpu02 58.9% 0.0% 7.7% 0.0% 0.1% 0.0% 33.0% + cpu03 52.5% 0.0% 4.1% 0.0% 0.1% 0.0% 43.0% +Mem: 3857224k av, 3307416k used, 549808k free, 0k shrd, 80640k +buff + 2224424k actv, 482552k in_d, 49416k in_c +Swap: 4281272k av, 10032k used, 4271240k free 2602424k +cached + +As you can see, we don't swap, we have free memory, we have all our data +cached (our database size is 1.5 GB). + +Context switch are between 10,000 and 20,000 per seconds. + +> This concept works for other tables as well. If you have a tables that +> both want services at the same time, disk arm contention will drag +> performance into the floor when they are on the same HW set. +> Profile your HD access and put tables that want to be accessed at the +> same time on different HD sets. Even if you have to buy more HW to do it. + +I use iostat and I can only see a little write activity and no read +activity on both raid arrays. + +-- +Guillaume + +From pgsql-performance-owner@postgresql.org Tue Nov 22 10:37:54 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 37A10D7E62 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 10:37:53 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 50821-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 14:37:56 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from soufre.accelance.net (soufre.accelance.net [213.162.48.15]) + by svr1.postgresql.org (Postfix) with ESMTP id 7C475DAFA6 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 10:37:49 -0400 (AST) +Received: from [213.162.49.207] (gs.team.openwide.fr [213.162.49.207]) + (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) + (No client certificate requested) + by soufre.accelance.net (Postfix) with ESMTP id 686FA5D23; + Tue, 22 Nov 2005 15:37:53 +0100 (CET) +Message-ID: <43832D40.7020309@openwide.fr> +Date: Tue, 22 Nov 2005 15:37:52 +0100 +From: Guillaume Smet <guillaume.smet@openwide.fr> +User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc3 (X11/20050929) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Claus Guttesen <kometen@gmail.com> +CC: Andrew Sullivan <ajs@crankycanuck.ca>, + pgsql-performance@postgresql.org +Subject: Re: weird performances problem +References: <437CC21D.8070402@openwide.fr> + <20051117221314.GC26696@phlogiston.dyndns.org> + <437D13AA.4010309@openwide.fr> + <b41c75520511171615g7c0fe923l@mail.gmail.com> +In-Reply-To: <b41c75520511171615g7c0fe923l@mail.gmail.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/441 +X-Sequence-Number: 15698 + +Claus and Andrew, + +Claus Guttesen wrote: +> Isn't sort_mem quite high? Remember that sort_mem size is allocated +> for each sort, not for each connection. Mine is 4096 (4 MB). My +> effective_cache_size is set to 27462. + +I tested sort mem from 4096 to 32768 (4096, 8192, 16384, 32768) this +afternoon and 32768 is definitely the best value for us. We still have +free memory using it, we don't have any swap and queries are generally +faster (I log all queries taking more than 500ms and the log is growing +far faster with lower values of sort_mem). + +> What OS are you running? + +# cat /etc/redhat-release +CentOS release 3.6 (Final) +so it's a RHEL 3 upd 6. + +# uname -a +Linux our.host 2.4.21-37.ELsmp #1 SMP Wed Sep 28 14:05:46 EDT 2005 i686 +i686 i386 GNU/Linux + +# cat /proc/cpuinfo +4x +processor : 3 +vendor_id : GenuineIntel +cpu family : 15 +model : 2 +model name : Intel(R) Xeon(TM) MP CPU 2.20GHz +stepping : 6 +cpu MHz : 2192.976 +cache size : 512 KB + +# cat /proc/meminfo + total: used: free: shared: buffers: cached: +Mem: 3949797376 3478376448 471420928 0 83410944 2679156736 +Swap: 4384022528 9797632 4374224896 +MemTotal: 3857224 kB +MemFree: 460372 kB +MemShared: 0 kB +Buffers: 81456 kB +Cached: 2610764 kB + +HTH + +Regards, + +-- +Guillaume + +From pgsql-performance-owner@postgresql.org Tue Nov 22 10:49:26 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9451CDAFCD + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 10:49:24 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 50566-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 14:49:27 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtpauth06.mail.atl.earthlink.net + (smtpauth06.mail.atl.earthlink.net [209.86.89.66]) + by svr1.postgresql.org (Postfix) with ESMTP id A3E8DDA86D + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 10:49:21 -0400 (AST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; + d=earthlink.net; + b=QB/IVAHZCzsnDfOt3xlb8+yjYTfEdFwHVkBl6s7wtIAgGZPR1fH7gR4ZbJ5xGvsX; + h=Received:Message-Id:X-Mailer:Date:To:From:Subject:In-Reply-To:References:Mime-Version:Content-Type:X-ELNK-Trace:X-Originating-IP; +Received: from [71.243.20.20] (helo=ron-6d52adff2a6.earthlink.net) + by smtpauth06.mail.atl.earthlink.net with asmtp (Exim 4.34) + id 1EeZSW-0007yg-NV; Tue, 22 Nov 2005 09:49:24 -0500 +Message-Id: <6.2.5.6.0.20051122093227.040fd900@earthlink.net> +X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6 +Date: Tue, 22 Nov 2005 09:49:17 -0500 +To: Guillaume Smet <guillaume.smet@openwide.fr>, + pgsql-performance@postgresql.org +From: Ron <rjpeace@earthlink.net> +Subject: Re: weird performances problem +In-Reply-To: <43832AA3.6080606@openwide.fr> +References: <437CC21D.8070402@openwide.fr> <dlugsf$25o5$1@news.hub.org> + <4382EB58.3020804@openwide.fr> + <6.2.5.6.0.20051122074454.040fae60@earthlink.net> + <43832AA3.6080606@openwide.fr> +Mime-Version: 1.0 +Content-Type: text/plain; charset="us-ascii"; format=flowed +X-ELNK-Trace: + acd68a6551193be5d780f4a490ca69563f9fea00a6dd62bc3363ff9f20874929048a1cebca4dcf46350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c +X-Originating-IP: 71.243.20.20 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.359 required=5 tests=[AWL=-0.120, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.359 +X-Spam-Level: +X-Archive-Number: 200511/442 +X-Sequence-Number: 15699 + +At 09:26 AM 11/22/2005, Guillaume Smet wrote: +>Ron wrote: +>>If I understand your HW config correctly, all of the pg stuff is on +>>the same RAID 10 set? +> +>No, the system and the WAL are on a RAID 1 array and the data on +>their own RAID 10 array. + +As has been noted many times around here, put the WAL on its own +dedicated HD's. You don't want any head movement on those HD's. + + +>As I said earlier, there's only a few writes in the database so I'm +>not really sure the WAL can be a limitation: IIRC, it's only used +>for writes isn't it? + +When you reach a WAL checkpoint, pg commits WAL data to HD... ...and +does almost nothing else until said commit is done. + + +>Don't you think we should have some io wait if the database was +>waiting for the WAL? We _never_ have any io wait on this server but +>our CPUs are still 30-40% idle. +_Something_ is doing long bursts of write IO on sdb and sdb1 every 30 +minutes or so according to your previous posts. + +Profile your DBMS and find out what. + + +>A typical top we have on this server is: +> 15:22:39 up 24 days, 13:30, 2 users, load average: 3.86, 3.96, 3.99 +>156 processes: 153 sleeping, 3 running, 0 zombie, 0 stopped +>CPU states: cpu user nice system irq softirq iowait idle +> total 50.6% 0.0% 4.7% 0.0% 0.6% 0.0% 43.8% +> cpu00 47.4% 0.0% 3.1% 0.3% 1.5% 0.0% 47.4% +> cpu01 43.7% 0.0% 3.7% 0.0% 0.5% 0.0% 51.8% +> cpu02 58.9% 0.0% 7.7% 0.0% 0.1% 0.0% 33.0% +> cpu03 52.5% 0.0% 4.1% 0.0% 0.1% 0.0% 43.0% +>Mem: 3857224k av, 3307416k used, 549808k free, 0k shrd, 80640k buff +> 2224424k actv, 482552k in_d, 49416k in_c +>Swap: 4281272k av, 10032k used, 4271240k +>free 2602424k cached +> +>As you can see, we don't swap, we have free memory, we have all our +>data cached (our database size is 1.5 GB). +> +>Context switch are between 10,000 and 20,000 per seconds. +That's actually a reasonably high CS rate. Again, why? + + +>>This concept works for other tables as well. If you have tables +>>that both want services at the same time, disk arm contention will +>>drag performance into the floor when they are on the same HW set. +>>Profile your HD access and put tables that want to be accessed at +>>the same time on different HD sets. Even if you have to buy more HW to do it. +> +>I use iostat and I can only see a little write activity and no read +>activity on both raid arrays. +Remember it's not just the overall amount, it's _when_and _where_ the +write activity takes place. If you have almost no write activity, +but whenever it happens it all happens to the same place by multiple +things contending for the same HDs, your performance during that time +will be poor. + +Since the behavior you are describing fits that cause very well, I'd +see if you can verify that's what's going on. + +Ron + + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 11:26:17 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6161EDAFFF + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 11:26:16 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 62230-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 15:26:19 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from soufre.accelance.net (soufre.accelance.net [213.162.48.15]) + by svr1.postgresql.org (Postfix) with ESMTP id 8C28ADAFE3 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 11:26:13 -0400 (AST) +Received: from [213.162.49.207] (gs.team.openwide.fr [213.162.49.207]) + (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) + (No client certificate requested) + by soufre.accelance.net (Postfix) with ESMTP id 63E965D2E; + Tue, 22 Nov 2005 16:26:18 +0100 (CET) +Message-ID: <43833899.5080408@openwide.fr> +Date: Tue, 22 Nov 2005 16:26:17 +0100 +From: Guillaume Smet <guillaume.smet@openwide.fr> +User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc3 (X11/20050929) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Ron <rjpeace@earthlink.net> +CC: pgsql-performance@postgresql.org +Subject: Re: weird performances problem +References: <437CC21D.8070402@openwide.fr> <dlugsf$25o5$1@news.hub.org> + <4382EB58.3020804@openwide.fr> + <6.2.5.6.0.20051122074454.040fae60@earthlink.net> + <43832AA3.6080606@openwide.fr> + <6.2.5.6.0.20051122093227.040fd900@earthlink.net> +In-Reply-To: <6.2.5.6.0.20051122093227.040fd900@earthlink.net> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/443 +X-Sequence-Number: 15700 + +Ron, + +First of all, thanks for your time. + +> As has been noted many times around here, put the WAL on its own +> dedicated HD's. You don't want any head movement on those HD's. + +Yep, I know that. That's just we supposed it was not so important if it +was nearly a readonly database which is wrong according to you. + +> _Something_ is doing long bursts of write IO on sdb and sdb1 every 30 +> minutes or so according to your previous posts. + +It's not every 30 minutes. It's a 20-30 minutes slow down 3-4 times a +day when we have a high load. +Anyway apart from this problem which is temporary, we have cpu idle all +the day when we don't have any io wait (and nearly no write) and the +server is enough loaded to use all the 4 cpus. I don't think it's normal. +It's not a very good idea but do you think we can put fsync to off +during a few minutes to check if the WAL is effectively our problem? A +simple reload of the configuration seems to take it into account. So can +we disable it temporarily even when the database is running? +If it is the case, I think we'll test it and if it solved our problem, +we'll ask our customer to buy two new disks to have a specific RAID 1 +array for the pg_xlog. + +> That's actually a reasonably high CS rate. Again, why? + +I'm not so surprised considering what I read before about Xeon +multiprocessors, pg 7.4 and the famous context switch storm. We are +planning a migration to 8.1 to (hopefully) solve this problem. Perhaps +our problem is due to that high CS rate. + +-- +Guillaume + +From pgsql-performance-owner@postgresql.org Tue Nov 22 12:50:39 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 53701D9422 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 12:50:38 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 76200-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 16:50:36 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from frank.wiles.org (frank.wiles.org [24.124.39.75]) + by svr1.postgresql.org (Postfix) with ESMTP id 06CE7D86C2 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 12:50:34 -0400 (AST) +Received: from kungfu (frank.wiles.org [127.0.0.1]) + by frank.wiles.org (8.13.1/8.13.1) with SMTP id jAMGoNEL014106; + Tue, 22 Nov 2005 10:50:23 -0600 +Date: Tue, 22 Nov 2005 10:51:00 -0600 +From: Frank Wiles <frank@wiles.org> +To: Marek Dabrowski <marek.dabrowski@infor.pl> +Cc: pgsql-performance@postgresql.org +Subject: Re: System queue +Message-Id: <20051122105100.57e8b60d.frank@wiles.org> +In-Reply-To: <438329C3.9060603@infor.pl> +References: <438329C3.9060603@infor.pl> +X-Mailer: Sylpheed version 2.0.1 (GTK+ 2.6.10; i686-pc-linux-gnu) +Mime-Version: 1.0 +Content-Type: text/plain; charset=US-ASCII +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/444 +X-Sequence-Number: 15701 + +On Tue, 22 Nov 2005 15:22:59 +0100 +Marek Dabrowski <marek.dabrowski@infor.pl> wrote: + +> Hello +> +> On my serwer Linux Fedora, HP DL360G3 with 2x3.06 GHz 4GB RAM working +> postgresql 7.4.6. Cpu utilization is about 40-50% but system process +> queue is long - about 6 task. Do you have nay sugestion/solution? + + We're going to need a lot more information than that to diagnose what + is going on. Do you have any functions or queries that will need to + use a large amount of CPU? + + In general I would suggest upgrading to the latest Fedora and moving + to PostgreSQL 8.x. Doing this will get you some extra performance, + but will probably not entirely solve your problem. + + --------------------------------- + Frank Wiles <frank@wiles.org> + http://www.wiles.org + --------------------------------- + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 13:00:09 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B533DD9566 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 13:00:07 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 77523-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 17:00:05 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 30EE3D86C2 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 13:00:04 -0400 (AST) +Received: from vt-pe2550-001.VANTAGE.vantage.com (unknown [64.80.203.244]) + by svr2.postgresql.org (Postfix) with ESMTP id 221CFF0B3E + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 17:00:02 +0000 (GMT) +X-MimeOLE: Produced By Microsoft Exchange V6.0.6249.0 +content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: multipart/alternative; + boundary="----_=_NextPart_001_01C5EF86.291240F5" +Subject: High context switches occurring +Date: Tue, 22 Nov 2005 11:59:54 -0500 +Message-ID: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098E73@vt-pe2550-001.vantage.vantage.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: High context switches occurring +Thread-Index: AcXvhij/yG5JlLcwS8iN+UVyKbhXtA== +From: "Anjan Dave" <adave@vantage.com> +To: <pgsql-performance@postgresql.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.48 required=5 tests=[DNS_FROM_RFC_ABUSE=0.479, + HTML_MESSAGE=0.001] +X-Spam-Score: 0.48 +X-Spam-Level: +X-Archive-Number: 200511/445 +X-Sequence-Number: 15702 + +This is a multi-part message in MIME format. + +------_=_NextPart_001_01C5EF86.291240F5 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable + +Hi, + +=20 + +One of our PG server is experiencing extreme slowness and there are +hundreds of SELECTS building up. I am not sure if heavy context +switching is the cause of this or something else is causing it. + +=20 + +Is this pretty much the final word on this issue? + +http://archives.postgresql.org/pgsql-performance/2004-04/msg00249.php + +=20 + +procs memory swap io system +cpu + + r b swpd free buff cache si so bi bo in +cs us sy id wa + + 2 0 20 2860544 124816 8042544 0 0 0 0 0 0 0 +0 0 0 + + 2 0 20 2860376 124816 8042552 0 0 0 24 157 115322 13 +10 76 0 + + 3 0 20 2860364 124840 8042540 0 0 0 228 172 120003 12 +10 77 0 + + 2 0 20 2860364 124840 8042540 0 0 0 20 158 118816 15 +10 75 0 + + 2 0 20 2860080 124840 8042540 0 0 0 10 152 117858 12 +11 77 0 + + 1 0 20 2860080 124848 8042572 0 0 0 210 202 114724 14 +10 76 0 + + 2 0 20 2860080 124848 8042572 0 0 0 20 169 114843 13 +10 77 0 + + 3 0 20 2859908 124860 8042576 0 0 0 188 180 115134 14 +11 75 0 + + 3 0 20 2859848 124860 8042576 0 0 0 20 173 113470 13 +10 77 0 + + 2 0 20 2859836 124860 8042576 0 0 0 10 157 112839 14 +11 75 0 + +=20 + +The system seems to be fine on iowait/memory side, except the CPU being +busy with the CS. Here's the top output: + +=20 + +11:54:57 up 59 days, 14:11, 2 users, load average: 1.13, 1.66, 1.52 + +282 processes: 281 sleeping, 1 running, 0 zombie, 0 stopped + +CPU states: cpu user nice system irq softirq iowait idle + + total 13.8% 0.0% 9.7% 0.0% 0.0% 0.0% 76.2% + + cpu00 12.3% 0.0% 10.5% 0.0% 0.0% 0.1% 76.8% + + cpu01 12.1% 0.0% 6.1% 0.0% 0.0% 0.1% 81.5% + + cpu02 10.9% 0.0% 9.1% 0.0% 0.0% 0.0% 79.9% + + cpu03 19.4% 0.0% 14.9% 0.0% 0.0% 0.0% 65.6% + + cpu04 13.9% 0.0% 11.1% 0.0% 0.0% 0.0% 74.9% + + cpu05 14.9% 0.0% 9.1% 0.0% 0.0% 0.0% 75.9% + + cpu06 12.9% 0.0% 8.9% 0.0% 0.0% 0.0% 78.1% + + cpu07 14.3% 0.0% 8.1% 0.0% 0.1% 0.0% 77.3% + +Mem: 12081720k av, 9273304k used, 2808416k free, 0k shrd, +126048k buff + + 4686808k actv, 3211872k in_d, 170240k in_c + +Swap: 4096532k av, 20k used, 4096512k free 8044072k +cached + +=20 + +=20 + +PostgreSQL 7.4.7 on i686-redhat-linux-gnu + +Red Hat Enterprise Linux AS release 3 (Taroon Update 5) + +Linux vl-pe6650-004 2.4.21-32.0.1.ELsmp + +=20 + +This is a Dell Quad XEON. Hyperthreading is turned on, and I am planning +to turn it off as soon as I get a chance to bring it down. + +=20 + +WAL is on separate drives from the OS and database. + +=20 + +Appreciate any inputs please.... + +=20 + +Thanks, +Anjan + +=20 + +=20 + + +------_=_NextPart_001_01C5EF86.291240F5 +Content-Type: text/html; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable + +<html xmlns:o=3D"urn:schemas-microsoft-com:office:office" = +xmlns:w=3D"urn:schemas-microsoft-com:office:word" = +xmlns=3D"http://www.w3.org/TR/REC-html40"> + +<head> +<meta http-equiv=3DContent-Type content=3D"text/html; = +charset=3Dus-ascii"> +<meta name=3DGenerator content=3D"Microsoft Word 11 (filtered medium)"> +<style> +<!-- + /* Style Definitions */ + p.MsoNormal, li.MsoNormal, div.MsoNormal + {margin:0in; + margin-bottom:.0001pt; + font-size:12.0pt; + font-family:"Times New Roman";} +a:link, span.MsoHyperlink + {color:blue; + text-decoration:underline;} +a:visited, span.MsoHyperlinkFollowed + {color:purple; + text-decoration:underline;} +span.EmailStyle17 + {mso-style-type:personal-compose; + font-family:Arial; + color:windowtext;} +@page Section1 + {size:8.5in 11.0in; + margin:1.0in 1.25in 1.0in 1.25in;} +div.Section1 + {page:Section1;} +--> +</style> + +</head> + +<body lang=3DEN-US link=3Dblue vlink=3Dpurple> + +<div class=3DSection1> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>Hi,<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'><o:p> </o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>One of our PG server is experiencing extreme slowness = +and +there are hundreds of SELECTS building up. I am not sure if heavy = +context +switching is the cause of this or something else is causing = +it.<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'><o:p> </o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>Is this pretty much the final word on this = +issue?<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'><a +href=3D"http://archives.postgresql.org/pgsql-performance/2004-04/msg00249= +.php">http://archives.postgresql.org/pgsql-performance/2004-04/msg00249.p= +hp</a><o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'><o:p> </o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>procs        &= +nbsp;           &n= +bsp; +memory      +swap          +io     +system         = +cpu<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'> r  b   swpd   +free   buff  cache  = +            s= +i   +so   bi    bo   in    = +cs       us +sy id wa<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'> 2  0     20 2860544 = +124816 +8042544    0    0     +0     0    0     = +0  +0  0  0  0<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'> 2  0     20 2860376 = +124816 +8042552    0    0     +0    24  157 115322 13 10 76  = +0<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'> 3  0     20 2860364 = +124840 +8042540    0    0     +0   228  172 120003 12 10 77  = +0<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'> 2  0     20 2860364 = +124840 +8042540    0    0     +0    20  158 118816 15 10 75  = +0<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'> 2  0     20 2860080 = +124840 +8042540    0    0     +0    10  152 117858 12 11 77  = +0<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'> 1  0     20 2860080 = +124848 +8042572    0    0     +0   210  202 114724 14 10 76  = +0<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'> 2  0     20 2860080 = +124848 +8042572    0    0     +0    20  169 114843 13 10 77  = +0<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'> 3  0     20 2859908 = +124860 +8042576    0    0     +0   188  180 115134 14 11 75  = +0<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'> 3  0     20 2859848 = +124860 +8042576    0    0     +0    20  173 113470 13 10 77  = +0<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'> 2  0     20 2859836 = +124860 +8042576    0    0     +0    10  157 112839 14 11 75  = +0<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'><o:p> </o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>The system seems to be fine on iowait/memory side, = +except +the CPU being busy with the CS. Here’s the top = +output:<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'><o:p> </o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>11:54:57  up 59 days, 14:11,  2 = +users,  load +average: 1.13, 1.66, 1.52<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>282 processes: 281 sleeping, 1 running, 0 zombie, 0 = +stopped<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>CPU states:  cpu    +user    nice  system    irq  +softirq  iowait    idle<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>         = +  +total   13.8%    0.0%    = +9.7%   +0.0%     0.0%    0.0%   = +76.2%<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>         = +  +cpu00   12.3%    0.0%   = +10.5%   +0.0%     0.0%    0.1%   = +76.8%<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>         = +  +cpu01   12.1%    0.0%    +6.1%   0.0%     0.0%    +0.1%   81.5%<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>         = +  +cpu02   10.9%    0.0%    +9.1%   0.0%     0.0%    +0.0%   79.9%<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>    = +       cpu03   +19.4%    0.0%   14.9%   +0.0%     0.0%    0.0%   = +65.6%<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>         = +  +cpu04   13.9%    0.0%   = +11.1%   +0.0%     0.0%    0.0%   = +74.9%<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>         = +  +cpu05   14.9%    0.0%    +9.1%   0.0%     0.0%    +0.0%   75.9%<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>         = +  +cpu06   12.9%    0.0%    8.9% = +  0.0%     +0.0%    0.0%   = +78.1%<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>         = +  +cpu07   14.3%    0.0%    +8.1%   0.0%     0.1%    +0.0%   77.3%<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>Mem:  12081720k av, 9273304k used, 2808416k +free,       0k shrd,  126048k = +buff<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>         = +          +4686808k actv, 3211872k in_d,  170240k = +in_c<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>Swap: 4096532k av,      20k = +used, +4096512k +free           &nb= +sp;     +8044072k cached<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'><o:p> </o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'><o:p> </o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>PostgreSQL 7.4.7 on = +i686-redhat-linux-gnu<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>Red Hat Enterprise Linux AS release 3 (Taroon Update = +5)<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>Linux vl-pe6650-004 = +2.4.21-32.0.1.ELsmp<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'><o:p> </o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>This is a Dell Quad XEON. Hyperthreading is turned = +on, and I +am planning to turn it off as soon as I get a chance to bring it = +down.<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'><o:p> </o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>WAL is on separate drives from the OS and = +database.<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'><o:p> </o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>Appreciate any inputs = +please….<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'><o:p> </o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'>Thanks,<br> +Anjan<o:p></o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'><o:p> </o:p></span></font></p> + +<p class=3DMsoNormal><font size=3D2 face=3DArial><span = +style=3D'font-size:10.0pt; +font-family:Arial'><o:p> </o:p></span></font></p> + +</div> + +</body> + +</html> + +------_=_NextPart_001_01C5EF86.291240F5-- + +From pgsql-performance-owner@postgresql.org Tue Nov 22 13:15:01 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 3F607DB081 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 13:15:00 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 79451-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 17:14:58 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from yertle.kcilink.com (yertle.kcilink.com [65.205.34.180]) + by svr1.postgresql.org (Postfix) with ESMTP id B6303DB080 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 13:14:56 -0400 (AST) +Received: from [192.168.7.103] (host-103.int.kcilink.com [192.168.7.103]) + by yertle.kcilink.com (Postfix) with ESMTP id D67FAB80D + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 12:14:55 -0500 (EST) +Mime-Version: 1.0 (Apple Message framework v746.2) +In-Reply-To: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098E73@vt-pe2550-001.vantage.vantage.com> +References: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098E73@vt-pe2550-001.vantage.vantage.com> +Content-Type: multipart/alternative; boundary=Apple-Mail-2--246327675 +Message-Id: <0D46FCC7-9DB2-4B45-B7C3-4F76EF53DB1F@khera.org> +From: Vivek Khera <vivek@khera.org> +Subject: Re: High context switches occurring +Date: Tue, 22 Nov 2005 12:14:54 -0500 +To: Postgresql Performance <pgsql-performance@postgresql.org> +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.129 required=5 tests=[AWL=-0.128, + HTML_FONT_BIG=0.256, HTML_MESSAGE=0.001] +X-Spam-Score: 0.129 +X-Spam-Level: +X-Archive-Number: 200511/446 +X-Sequence-Number: 15703 + + +--Apple-Mail-2--246327675 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; + charset=US-ASCII; + delsp=yes; + format=flowed + + +On Nov 22, 2005, at 11:59 AM, Anjan Dave wrote: +> This is a Dell Quad XEON. Hyperthreading is turned on, and I am +> planning to turn it off as soon as I get a chance to bring it down. +> + +You should probably also upgrade to Pg 8.0 or newer since it is a +known problem with XEON processors and older postgres versions. +Upgrading Pg may solve your problem or it may not. It is just a +fluke with XEON processors... + + + +--Apple-Mail-2--246327675 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/html; + charset=ISO-8859-1 + +<HTML><BODY style=3D"word-wrap: break-word; -khtml-nbsp-mode: space; = +-khtml-line-break: after-white-space; "><BR><DIV><DIV>On Nov 22, 2005, = +at 11:59 AM, Anjan Dave wrote:<FONT size=3D"2" face=3D"Arial"><SPAN = +style=3D"font-size:10.0pt; font-family:Arial; font-size: 13.3333px; = +"><O:P style=3D"font-family: Arial; font-size: 13.3333px; "><SPAN = +class=3D"Apple-style-span" style=3D"font-family: Arial; font-size: = +13.3333px; ">=A0</SPAN></O:P></SPAN></FONT></DIV><BLOCKQUOTE = +type=3D"cite"><SPAN class=3D"Apple-style-span" style=3D"border-collapse: = +separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: = +Georgia; font-size: 14px; font-style: normal; font-variant: normal; = +font-weight: normal; letter-spacing: normal; line-height: normal; = +text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: = +0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; = +white-space: normal; widows: 2; word-spacing: 0px; "><P = +class=3D"MsoNormal"><FONT size=3D"2" face=3D"Arial"><SPAN = +style=3D"font-size:10.0pt; font-family:Arial; font-size: 13.3333px; = +"><SPAN class=3D"Apple-style-span" style=3D"font-family: Arial; = +font-size: 13.3333px; ">This is a Dell Quad XEON. Hyperthreading is = +turned on, and I am planning to turn it off as soon as I get a chance to = +bring it down.</SPAN></SPAN></FONT></P><P class=3D"MsoNormal"><FONT = +class=3D"Apple-style-span" face=3D"Arial" size=3D"4"><SPAN = +class=3D"Apple-style-span" style=3D"font-size: = +13.3333px;"></SPAN></FONT></P></SPAN></BLOCKQUOTE><BR></DIV><DIV>You = +should probably also upgrade to Pg 8.0 or newer since it is a known = +problem with XEON processors and older postgres versions.=A0 Upgrading = +Pg may solve your problem or it may not.=A0 It is just a fluke with XEON = +processors...</DIV><DIV><BR class=3D"khtml-block-placeholder"></DIV><FONT = +class=3D"Apple-style-span" face=3D"Arial" size=3D"4"><SPAN = +class=3D"Apple-style-span" style=3D"font-size: = +13.3333px;"><BR></SPAN></FONT></BODY></HTML>= + +--Apple-Mail-2--246327675-- + +From pgsql-performance-owner@postgresql.org Tue Nov 22 13:20:11 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A1BE4D99B8 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 13:20:10 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 79236-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 17:20:08 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtpauth08.mail.atl.earthlink.net + (smtpauth08.mail.atl.earthlink.net [209.86.89.68]) + by svr1.postgresql.org (Postfix) with ESMTP id 891ADD9566 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 13:20:07 -0400 (AST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; + d=earthlink.net; + b=lePpJKcWBLv8h7SAVMmS2MCzMtfIQH19xpQcm6snSxC3ehVx5fu7sBh8AE32+eBk; + h=Received:Message-Id:X-Mailer:Date:To:From:Subject:In-Reply-To:References:Mime-Version:Content-Type:X-ELNK-Trace:X-Originating-IP; +Received: from [71.243.20.20] (helo=ron-6d52adff2a6.earthlink.net) + by smtpauth08.mail.atl.earthlink.net with asmtp (Exim 4.34) + id 1EeboI-0000pv-Sn; Tue, 22 Nov 2005 12:20:03 -0500 +Message-Id: <6.2.5.6.0.20051122120225.040f8658@earthlink.net> +X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6 +Date: Tue, 22 Nov 2005 12:19:57 -0500 +To: Guillaume Smet <guillaume.smet@openwide.fr>, + pgsql-performance@postgresql.org +From: Ron <rjpeace@earthlink.net> +Subject: Re: weird performances problem +In-Reply-To: <43833899.5080408@openwide.fr> +References: <437CC21D.8070402@openwide.fr> <dlugsf$25o5$1@news.hub.org> + <4382EB58.3020804@openwide.fr> + <6.2.5.6.0.20051122074454.040fae60@earthlink.net> + <43832AA3.6080606@openwide.fr> + <6.2.5.6.0.20051122093227.040fd900@earthlink.net> + <43833899.5080408@openwide.fr> +Mime-Version: 1.0 +Content-Type: text/plain; charset="us-ascii"; format=flowed +X-ELNK-Trace: + acd68a6551193be5d780f4a490ca69563f9fea00a6dd62bc434ee0091acf86fe28fe76da498402b6350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c +X-Originating-IP: 71.243.20.20 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.359 required=5 tests=[AWL=-0.120, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.359 +X-Spam-Level: +X-Archive-Number: 200511/447 +X-Sequence-Number: 15704 + +At 10:26 AM 11/22/2005, Guillaume Smet wrote: +>Ron, +> +>First of all, thanks for your time. +Happy to help. + + +>>As has been noted many times around here, put the WAL on its own +>>dedicated HD's. You don't want any head movement on those HD's. +> +>Yep, I know that. That's just we supposed it was not so important if +>it was nearly a readonly database which is wrong according to you. +It's just good practice with pg that pg-xlog should always get it's +own dedicated HD set. OTOH, I'm not at all convinced given the scant +evidence so far that it is the primary problem here; particularly +since if I understand you correctly, px-xlog is not on sdb or sdb1 +where you are having the write storm. + + +>>_Something_ is doing long bursts of write IO on sdb and sdb1 every +>>30 minutes or so according to your previous posts. +> +>It's not every 30 minutes. It's a 20-30 minutes slow down 3-4 times +>a day when we have a high load. + +Thanks for the correction and I apologize for the misunderstanding. +Clearly the first step is to instrument sdb and sdb1 so that you +understand exactly what is being accessed and written on them. + +Possibilities that come to mind: +a) Are some of your sorts requiring more than 32MB during high +load? If sorts do not usually require HD temp files and suddenly do, +you could get behavior like yours. + +b) Are you doing too many 32MB sorts during high load? Same comment as above. + +c) Are you doing some sort of data updates or appends during high +load that do not normally occur? + +d) Are you constantly doing "a little" write IO that turns into a +write storm under high load because of queuing issues? + +Put the scaffolding in needed to trace _exactly_ what's happening on +sdb and sdb1 throughout the day and then examine the traces over a +day, a few days, and a week. I'll bet you will notice some patterns +that will be helpful in identifying what's going on. + +Ron + + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 13:34:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 2F928DAFBD + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 13:34:45 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 81478-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 17:34:43 +0000 (GMT) +X-Greylist: delayed 00:06:36.58847 by SQLgrey- +Received: from jefftrout.com (pool-71-248-161-64.bstnma.fios.verizon.net + [71.248.161.64]) + by svr1.postgresql.org (Postfix) with SMTP id A6F11D99B8 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 13:34:41 -0400 (AST) +Received: (qmail 23962 invoked from network); 22 Nov 2005 17:28:38 -0000 +Received: from pool-71-248-161-64.bstnma.fios.verizon.net (HELO + ?10.10.10.105?) (71.248.161.64) + by 192.168.0.101 with SMTP; 22 Nov 2005 17:28:38 -0000 +In-Reply-To: <438329C3.9060603@infor.pl> +References: <438329C3.9060603@infor.pl> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed +Message-Id: <E09D46F0-6DFC-4410-A00D-CA5301A88CF3@torgo.978.org> +Cc: Pgsql-Performance <pgsql-performance@postgresql.org> +Content-Transfer-Encoding: 7bit +From: Jeff Trout <threshar@torgo.978.org> +Subject: Re: System queue +Date: Tue, 22 Nov 2005 12:28:00 -0500 +To: Marek Dabrowski <marek.dabrowski@infor.pl> +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/448 +X-Sequence-Number: 15705 + + +On Nov 22, 2005, at 9:22 AM, Marek Dabrowski wrote: + +> Hello +> +> On my serwer Linux Fedora, HP DL360G3 with 2x3.06 GHz 4GB RAM +> working postgresql 7.4.6. Cpu utilization is about 40-50% but +> system process queue is long - about 6 task. Do you have nay +> sugestion/solution?\ + +High run queue (loadavg) with low cpu usage means you are IO bound. +Either change some queries around to generate less IO, or add more +disks. + +-- +Jeff Trout <jeff@jefftrout.com> +http://www.jefftrout.com/ +http://www.stuarthamm.net/ + + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 13:35:54 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 374BFDB08A + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 13:35:53 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 80862-08-2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 17:35:51 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 59C41DB09D + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 13:35:50 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAMHZnCB012639; + Tue, 22 Nov 2005 12:35:49 -0500 (EST) +To: Vivek Khera <vivek@khera.org> +cc: Postgresql Performance <pgsql-performance@postgresql.org>, + "Anjan Dave" <adave@vantage.com> +Subject: Re: High context switches occurring +In-reply-to: <0D46FCC7-9DB2-4B45-B7C3-4F76EF53DB1F@khera.org> +References: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098E73@vt-pe2550-001.vantage.vantage.com> + <0D46FCC7-9DB2-4B45-B7C3-4F76EF53DB1F@khera.org> +Comments: In-reply-to Vivek Khera <vivek@khera.org> + message dated "Tue, 22 Nov 2005 12:14:54 -0500" +Date: Tue, 22 Nov 2005 12:35:49 -0500 +Message-ID: <12638.1132680949@sss.pgh.pa.us> +From: Tom Lane <tgl@sss.pgh.pa.us> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.003 required=5 tests=[AWL=0.003] +X-Spam-Score: 0.003 +X-Spam-Level: +X-Archive-Number: 200511/449 +X-Sequence-Number: 15706 + +Vivek Khera <vivek@khera.org> writes: +> On Nov 22, 2005, at 11:59 AM, Anjan Dave wrote: +>> This is a Dell Quad XEON. Hyperthreading is turned on, and I am +>> planning to turn it off as soon as I get a chance to bring it down. + +> You should probably also upgrade to Pg 8.0 or newer since it is a +> known problem with XEON processors and older postgres versions. +> Upgrading Pg may solve your problem or it may not. + +PG 8.1 is the first release that has a reasonable probability of +avoiding heavy contention for the buffer manager lock when there +are multiple CPUs. If you're going to update to try to fix this, +you need to go straight to 8.1. + +I've recently been chasing a report from Rob Creager that seems to +indicate contention on SubTransControlLock, so the slru code is +likely to be our next bottleneck to fix :-( + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Tue Nov 22 14:29:47 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 1C69ADB0B1 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 14:29:46 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 95514-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 18:29:43 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from europa.telenet-ops.be (europa.telenet-ops.be [195.130.137.75]) + by svr1.postgresql.org (Postfix) with ESMTP id 5C8DFDB0C6 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 14:29:39 -0400 (AST) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by europa.telenet-ops.be (Postfix) with SMTP id F2A803817B + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 19:29:37 +0100 (CET) +Received: from [10.0.1.2] (d5152B3BA.access.telenet.be [81.82.179.186]) + by europa.telenet-ops.be (Postfix) with ESMTP id A33AC38186 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 19:29:37 +0100 (CET) +Mime-Version: 1.0 (Apple Message framework v623) +To: pgsql-performance@postgresql.org +Message-Id: <e28aace15975ef9972fdd65ceb6e0ce8@implements.be> +Content-Type: multipart/mixed; boundary=Apple-Mail-210--241845262 +From: Yves Vindevogel <yves.vindevogel@implements.be> +Subject: Stored Procedure +Date: Tue, 22 Nov 2005 19:29:37 +0100 +X-Mailer: Apple Mail (2.623) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.823 required=5 tests=[RCVD_IN_SORBS_SOCKS=1.823] +X-Spam-Score: 1.823 +X-Spam-Level: * +X-Archive-Number: 200511/450 +X-Sequence-Number: 15707 + + +--Apple-Mail-210--241845262 +Content-Type: multipart/alternative; + boundary=Apple-Mail-211--241845262 + + +--Apple-Mail-211--241845262 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/plain; + charset=ISO-8859-1; + format=flowed + +Is there another way in PG to return a recordset from a function than=20 +to declare a type first ? + +create function fnTest () returns setof=20 +myDefinedTypeIDontWantToDefineFirst ... + + +Met vriendelijke groeten, +Bien =E0 vous, +Kind regards, + +Yves Vindevogel +Implements + + +--Apple-Mail-211--241845262 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/enriched; + charset=ISO-8859-1 + +Is there another way in PG to return a recordset from a function than +to declare a type first ? + + +create function fnTest () returns setof +myDefinedTypeIDontWantToDefineFirst ... + + + +Met vriendelijke groeten, + +Bien =E0 vous, + +Kind regards, + + +<bold>Yves Vindevogel</bold> + +<bold>Implements</bold> + +<smaller> + +</smaller>= + +--Apple-Mail-211--241845262-- + +--Apple-Mail-210--241845262 +Content-Transfer-Encoding: base64 +Content-Type: image/tiff; + x-unix-mode=0666; + name="Pasted Graphic 2.tiff" +Content-Disposition: inline; + filename="Pasted Graphic 2.tiff" + +TU0AKgAAFciAP6BP5/wWDQeEQmFQuGQ2HQ+FP5+v9rOh5P9IMBuP8zK9tP8fJNlP8QoNjP8FndhP +8MnyVjJHSMrqFnv9BL1vP9ett2v98PuJxChUOiUWGQOCUalUujOV4PZ/qBluR/mdVtJ/jVHst/ho +9MF/g08WABHJfv8AWa0WoAHFfWuzgg6sB/hY9ysUohjv8qqVqv9LMZxv9ouV40zEYmHUjFY2HPx+ +RNtOl4Rhftt/phiRs6LC/iA5LewnJeWg46W22+02cAHOwa26bC0HPY7TZ7G2G9dv8EHFdP8Om9YP +8rKJov9UtFzv9Dzh/sRvu5/vZ9PzHdeF4zsUqgQRlOR5v9DMBwv8uqe/jZIVwNHu6B0/WAKHvWGr +RAA1ra0G1c/vfgANrdraXrTQIAA6JW2TUrQNz/ja0oAjO4YAjSWS0DOWawjys4RkIk4Lj2sAWEUZ +B/ieUJqH+PZdnAf5aG06R5nsfLtqW7UaoWZJwukwLyi4VRsn+F5HGYf8QJWBQ7JWAI5tYti2Dm1T 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text/plain; + charset=US-ASCII; + format=flowed + + + +Mail: yves.vindevogel@implements.be - Mobile: +32 (478) 80 82 91 + +Kempische Steenweg 206 - 3500 Hasselt - Tel-Fax: +32 (11) 43 55 76 + +Web: http://www.implements.be + +First they ignore you. Then they laugh at you. Then they fight you. +Then you win. +Mahatma Ghandi. +--Apple-Mail-212--241845261 +Content-Transfer-Encoding: 7bit +Content-Type: text/enriched; + charset=US-ASCII + +<smaller> + + +Mail: yves.vindevogel@implements.be - Mobile: +32 (478) 80 82 91 + + +Kempische Steenweg 206 - 3500 Hasselt - Tel-Fax: +32 (11) 43 55 76 + + +Web: http://www.implements.be + +<italic><x-tad-smaller> + +First they ignore you. Then they laugh at you. Then they fight you. +Then you win. + +Mahatma Ghandi.</x-tad-smaller></italic></smaller> +--Apple-Mail-212--241845261-- + +--Apple-Mail-210--241845262-- + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 14:43:02 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B80FFDB0E1 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 14:43:01 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 94852-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 18:43:01 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 46B94DB08A + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 14:42:59 -0400 (AST) +Received: from amanda.contactbda.com (ipn36372-f65123.cidr.lightship.net + [216.204.66.227]) + by svr2.postgresql.org (Postfix) with ESMTP id 63B9BF0BC5 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 18:42:59 +0000 (GMT) +Received: from amanda.contactbda.com (amanda.contactbda.com [192.168.1.2]) + by amanda.contactbda.com (8.12.11/8.12.11/Debian-3) with ESMTP id + jAMIgrqj002394; Tue, 22 Nov 2005 13:42:53 -0500 +From: "Jim Buttafuoco" <jim@contactbda.com> +To: Yves Vindevogel <yves.vindevogel@implements.be>, + pgsql-performance@postgresql.org +Reply-To: jim@contactbda.com +Subject: Re: Stored Procedure +Date: Tue, 22 Nov 2005 13:42:53 -0500 +Message-Id: <20051122184119.M48526@contactbda.com> +In-Reply-To: <e28aace15975ef9972fdd65ceb6e0ce8@implements.be> +References: <e28aace15975ef9972fdd65ceb6e0ce8@implements.be> +X-Mailer: Open WebMail 2.41 20040926 +X-OriginatingIP: 192.168.1.1 (jim) +MIME-Version: 1.0 +Content-Type: text/plain; + charset=iso-8859-1 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/451 +X-Sequence-Number: 15708 + +create function abc() returns setof RECORD ... + +then to call it you would do +select * from abc() as (a text,b int,...); + + + + +---------- Original Message ----------- +From: Yves Vindevogel <yves.vindevogel@implements.be> +To: pgsql-performance@postgresql.org +Sent: Tue, 22 Nov 2005 19:29:37 +0100 +Subject: [PERFORM] Stored Procedure + +> Is there another way in PG to return a recordset from a function than +> to declare a type first ? +> +> create function fnTest () returns setof +> myDefinedTypeIDontWantToDefineFirst ... +> +> Met vriendelijke groeten, +> Bien � vous, +> Kind regards, +> +> Yves Vindevogel +> Implements +------- End of Original Message ------- + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 14:59:52 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D71DDDB0D0 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 14:59:51 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 97373-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 18:59:51 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from tigger.fuhr.org (tigger.fuhr.org [63.214.45.158]) + by svr1.postgresql.org (Postfix) with ESMTP id 08C14DB0C8 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 14:59:48 -0400 (AST) +Received: from winnie.fuhr.org (winnie.fuhr.org [10.1.0.1]) + by tigger.fuhr.org (8.13.3/8.13.3) with ESMTP id jAMIxgBl056556 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); + Tue, 22 Nov 2005 11:59:45 -0700 (MST) + (envelope-from mfuhr@winnie.fuhr.org) +Received: from winnie.fuhr.org (localhost [127.0.0.1]) + by winnie.fuhr.org (8.13.4/8.13.4) with ESMTP id jAMIxgsQ018202; + Tue, 22 Nov 2005 11:59:42 -0700 (MST) + (envelope-from mfuhr@winnie.fuhr.org) +Received: (from mfuhr@localhost) + by winnie.fuhr.org (8.13.4/8.13.4/Submit) id jAMIxgfL018201; + Tue, 22 Nov 2005 11:59:42 -0700 (MST) (envelope-from mfuhr) +Date: Tue, 22 Nov 2005 11:59:42 -0700 +From: Michael Fuhr <mike@fuhr.org> +To: Yves Vindevogel <yves.vindevogel@implements.be> +Cc: pgsql-performance@postgresql.org +Subject: Re: Stored Procedure +Message-ID: <20051122185941.GA18102@winnie.fuhr.org> +References: <e28aace15975ef9972fdd65ceb6e0ce8@implements.be> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <e28aace15975ef9972fdd65ceb6e0ce8@implements.be> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000, UPPERCASE_25_50=0] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/452 +X-Sequence-Number: 15709 + +On Tue, Nov 22, 2005 at 07:29:37PM +0100, Yves Vindevogel wrote: +> Is there another way in PG to return a recordset from a function than +> to declare a type first ? + +In 8.1 some languages support OUT and INOUT parameters. + +CREATE FUNCTION foo(IN x integer, INOUT y integer, OUT z integer) AS $$ +BEGIN + y := y * 10; + z := x * 10; +END; +$$ LANGUAGE plpgsql IMMUTABLE STRICT; + +SELECT * FROM foo(1, 2); + y | z +----+---- + 20 | 10 +(1 row) + +CREATE FUNCTION fooset(IN x integer, INOUT y integer, OUT z integer) +RETURNS SETOF record AS $$ +BEGIN + y := y * 10; + z := x * 10; + RETURN NEXT; + y := y + 1; + z := z + 1; + RETURN NEXT; +END; +$$ LANGUAGE plpgsql IMMUTABLE STRICT; + +SELECT * FROM fooset(1, 2); + y | z +----+---- + 20 | 10 + 21 | 11 +(2 rows) + +-- +Michael Fuhr + +From pgsql-performance-owner@postgresql.org Tue Nov 22 15:23:43 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id ACD90D7E05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 15:23:40 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 00743-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 19:23:40 +0000 (GMT) +X-Greylist: delayed 02:23:37.837591 by SQLgrey- +Received: from vt-pe2550-001.VANTAGE.vantage.com (unknown [64.80.203.244]) + by svr1.postgresql.org (Postfix) with ESMTP id 86718D80BA + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 15:23:36 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.0.6249.0 +content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: High context switches occurring +Date: Tue, 22 Nov 2005 14:23:34 -0500 +Message-ID: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785027001C1@vt-pe2550-001.vantage.vantage.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] High context switches occurring +Thread-Index: AcXvizKJ0RfGM9seSRqWYudicPH/OAADq+GA +From: "Anjan Dave" <adave@vantage.com> +To: "Tom Lane" <tgl@sss.pgh.pa.us>, + "Vivek Khera" <vivek@khera.org> +Cc: "Postgresql Performance" <pgsql-performance@postgresql.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.36 required=5 tests=[AWL=-0.119, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.36 +X-Spam-Level: +X-Archive-Number: 200511/453 +X-Sequence-Number: 15710 + +Thanks, guys, I'll start planning on upgrading to PG8.1 + +Would this problem change it's nature in any way on the recent Dual-Core +Intel XEON MP machines? + +Thanks, +Anjan + +-----Original Message----- +From: Tom Lane [mailto:tgl@sss.pgh.pa.us]=20 +Sent: Tuesday, November 22, 2005 12:36 PM +To: Vivek Khera +Cc: Postgresql Performance; Anjan Dave +Subject: Re: [PERFORM] High context switches occurring=20 + +Vivek Khera <vivek@khera.org> writes: +> On Nov 22, 2005, at 11:59 AM, Anjan Dave wrote: +>> This is a Dell Quad XEON. Hyperthreading is turned on, and I am =20 +>> planning to turn it off as soon as I get a chance to bring it down. + +> You should probably also upgrade to Pg 8.0 or newer since it is a =20 +> known problem with XEON processors and older postgres versions. =20 +> Upgrading Pg may solve your problem or it may not. + +PG 8.1 is the first release that has a reasonable probability of +avoiding heavy contention for the buffer manager lock when there +are multiple CPUs. If you're going to update to try to fix this, +you need to go straight to 8.1. + +I've recently been chasing a report from Rob Creager that seems to +indicate contention on SubTransControlLock, so the slru code is +likely to be our next bottleneck to fix :-( + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 15:41:44 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5391DD817C + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 15:41:43 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 03622-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 19:41:43 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 84A04D9566 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 15:41:40 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAMJfe2L013417; + Tue, 22 Nov 2005 14:41:40 -0500 (EST) +To: "Anjan Dave" <adave@vantage.com> +cc: "Vivek Khera" <vivek@khera.org>, + "Postgresql Performance" <pgsql-performance@postgresql.org> +Subject: Re: High context switches occurring +In-reply-to: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785027001C1@vt-pe2550-001.vantage.vantage.com> +References: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785027001C1@vt-pe2550-001.vantage.vantage.com> +Comments: In-reply-to "Anjan Dave" <adave@vantage.com> + message dated "Tue, 22 Nov 2005 14:23:34 -0500" +Date: Tue, 22 Nov 2005 14:41:40 -0500 +Message-ID: <13416.1132688500@sss.pgh.pa.us> +From: Tom Lane <tgl@sss.pgh.pa.us> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.003 required=5 tests=[AWL=0.003] +X-Spam-Score: 0.003 +X-Spam-Level: +X-Archive-Number: 200511/454 +X-Sequence-Number: 15711 + +"Anjan Dave" <adave@vantage.com> writes: +> Would this problem change it's nature in any way on the recent Dual-Core +> Intel XEON MP machines? + +Probably not much. + +There's some evidence that Opterons have less of a problem than Xeons +in multi-chip configurations, but we've seen CS thrashing on Opterons +too. I think the issue is probably there to some extent in any modern +SMP architecture. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Tue Nov 22 16:33:31 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 652E0DB7E5 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 16:33:30 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 20727-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 20:33:30 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from vt-pe2550-001.VANTAGE.vantage.com (unknown [64.80.203.244]) + by svr1.postgresql.org (Postfix) with ESMTP id 512C6DB7DB + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 16:33:26 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.0.6249.0 +content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: High context switches occurring +Date: Tue, 22 Nov 2005 15:33:26 -0500 +Message-ID: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098E76@vt-pe2550-001.vantage.vantage.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] High context switches occurring +Thread-Index: AcXvizKJ0RfGM9seSRqWYudicPH/OAADq+GAAACsshA= +From: "Anjan Dave" <adave@vantage.com> +To: "Anjan Dave" <adave@vantage.com>, "Tom Lane" <tgl@sss.pgh.pa.us>, + "Vivek Khera" <vivek@khera.org> +Cc: "Postgresql Performance" <pgsql-performance@postgresql.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.359 required=5 tests=[AWL=-0.119, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.359 +X-Spam-Level: +X-Archive-Number: 200511/455 +X-Sequence-Number: 15712 + +Is there any way to get a temporary relief from this Context Switching +storm? Does restarting postmaster help? + +It seems that I can recreate the heavy CS with just one SELECT +statement...and then when multiple such SELECT queries are coming in, +things just get hosed up until we cancel a bunch of queries... + +Thanks, +Anjan + + +-----Original Message----- +From: Anjan Dave=20 +Sent: Tuesday, November 22, 2005 2:24 PM +To: Tom Lane; Vivek Khera +Cc: Postgresql Performance +Subject: Re: [PERFORM] High context switches occurring=20 + +Thanks, guys, I'll start planning on upgrading to PG8.1 + +Would this problem change it's nature in any way on the recent Dual-Core +Intel XEON MP machines? + +Thanks, +Anjan + +-----Original Message----- +From: Tom Lane [mailto:tgl@sss.pgh.pa.us]=20 +Sent: Tuesday, November 22, 2005 12:36 PM +To: Vivek Khera +Cc: Postgresql Performance; Anjan Dave +Subject: Re: [PERFORM] High context switches occurring=20 + +Vivek Khera <vivek@khera.org> writes: +> On Nov 22, 2005, at 11:59 AM, Anjan Dave wrote: +>> This is a Dell Quad XEON. Hyperthreading is turned on, and I am =20 +>> planning to turn it off as soon as I get a chance to bring it down. + +> You should probably also upgrade to Pg 8.0 or newer since it is a =20 +> known problem with XEON processors and older postgres versions. =20 +> Upgrading Pg may solve your problem or it may not. + +PG 8.1 is the first release that has a reasonable probability of +avoiding heavy contention for the buffer manager lock when there +are multiple CPUs. If you're going to update to try to fix this, +you need to go straight to 8.1. + +I've recently been chasing a report from Rob Creager that seems to +indicate contention on SubTransControlLock, so the slru code is +likely to be our next bottleneck to fix :-( + + regards, tom lane + + +---------------------------(end of broadcast)--------------------------- +TIP 4: Have you searched our list archives? + + http://archives.postgresql.org + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 16:37:51 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 61D3DDB6B0 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 16:37:50 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 17304-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 20:37:50 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from koolancexeon.g2switchworks.com (mail.g2switchworks.com + [63.87.162.25]) + by svr1.postgresql.org (Postfix) with ESMTP id A515BDB48E + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 16:37:47 -0400 (AST) +Received: mail.g2switchworks.com 10.10.1.8 from 10.10.1.37 10.10.1.37 via HTTP + with MS-WebStorage 6.5.6944 +Received: from state.g2switchworks.com by mail.g2switchworks.com; + 22 Nov 2005 14:37:47 -0600 +Subject: Re: High context switches occurring +From: Scott Marlowe <smarlowe@g2switchworks.com> +To: Anjan Dave <adave@vantage.com> +Cc: Tom Lane <tgl@sss.pgh.pa.us>, Vivek Khera <vivek@khera.org>, + Postgresql Performance <pgsql-performance@postgresql.org> +In-Reply-To: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098E76@vt-pe2550-001.vantage.vantage.com> +References: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098E76@vt-pe2550-001.vantage.vantage.com> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Message-Id: <1132691867.28788.42.camel@state.g2switchworks.com> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) +Date: Tue, 22 Nov 2005 14:37:47 -0600 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/456 +X-Sequence-Number: 15713 + +On Tue, 2005-11-22 at 14:33, Anjan Dave wrote: +> Is there any way to get a temporary relief from this Context Switching +> storm? Does restarting postmaster help? +> +> It seems that I can recreate the heavy CS with just one SELECT +> statement...and then when multiple such SELECT queries are coming in, +> things just get hosed up until we cancel a bunch of queries... + +Is your machine a hyperthreaded one? Some folks have found that turning +off hyper threading helps. I knew it made my servers better behaved in +the past. + +From pgsql-performance-owner@postgresql.org Tue Nov 22 16:38:34 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 32530DB861 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 16:38:33 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 28630-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 20:38:33 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from koolancexeon.g2switchworks.com (mail.g2switchworks.com + [63.87.162.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 47CE1DB816 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 16:38:29 -0400 (AST) +Received: mail.g2switchworks.com 10.10.1.8 from 10.10.1.37 10.10.1.37 via HTTP + with MS-WebStorage 6.5.6944 +Received: from state.g2switchworks.com by mail.g2switchworks.com; + 22 Nov 2005 14:38:31 -0600 +Subject: Re: High context switches occurring +From: Scott Marlowe <smarlowe@g2switchworks.com> +To: Anjan Dave <adave@vantage.com> +Cc: Tom Lane <tgl@sss.pgh.pa.us>, Vivek Khera <vivek@khera.org>, + Postgresql Performance <pgsql-performance@postgresql.org> +In-Reply-To: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098E76@vt-pe2550-001.vantage.vantage.com> +References: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098E76@vt-pe2550-001.vantage.vantage.com> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Message-Id: <1132691910.28788.44.camel@state.g2switchworks.com> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) +Date: Tue, 22 Nov 2005 14:38:31 -0600 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.001 required=5 tests=[UNPARSEABLE_RELAY=0.001] +X-Spam-Score: 0.001 +X-Spam-Level: +X-Archive-Number: 200511/457 +X-Sequence-Number: 15714 + +P.s., followup to my last post, I don't know if turning of HT actually +lowered the number of context switches, just that it made my server run +faster. + +From pgsql-performance-owner@postgresql.org Tue Nov 22 18:17:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B8AB9DBCA1 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 18:17:45 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 96922-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 22:17:45 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from hoboe2bl1.telenet-ops.be (hoboe2bl1.telenet-ops.be + [195.130.137.73]) + by svr1.postgresql.org (Postfix) with ESMTP id B9C7EDA406 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 18:17:40 -0400 (AST) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by hoboe2bl1.telenet-ops.be (Postfix) with SMTP id 698E738187 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 23:17:42 +0100 (CET) +Received: from [10.0.1.2] (d5152B3BA.access.telenet.be [81.82.179.186]) + by hoboe2bl1.telenet-ops.be (Postfix) with ESMTP id 2DD9F38077 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 23:17:42 +0100 (CET) +Mime-Version: 1.0 (Apple Message framework v623) +In-Reply-To: <20051122184119.M48526@contactbda.com> +References: <e28aace15975ef9972fdd65ceb6e0ce8@implements.be> + <20051122184119.M48526@contactbda.com> +Content-Type: multipart/mixed; boundary=Apple-Mail-1--228161321 +Message-Id: <33f74d2a046b89d119c349e82b7398de@implements.be> +From: Yves Vindevogel <yves.vindevogel@implements.be> +Subject: Re: Stored Procedure +Date: Tue, 22 Nov 2005 23:17:41 +0100 +To: pgsql-performance@postgresql.org +X-Mailer: Apple Mail (2.623) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.823 required=5 tests=[RCVD_IN_SORBS_SOCKS=1.823] +X-Spam-Score: 1.823 +X-Spam-Level: * +X-Archive-Number: 200511/458 +X-Sequence-Number: 15715 + + +--Apple-Mail-1--228161321 +Content-Type: multipart/alternative; + boundary=Apple-Mail-2--228161320 + + +--Apple-Mail-2--228161320 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/plain; + charset=ISO-8859-1; + format=flowed + +But this does not work without the second line, right ? +BTW, the thing returned is not a record. It's a bunch of fields, not a=20= + +complete record or fields of multiple records. +I'm not so sure it works. + +On 22 Nov 2005, at 19:42, Jim Buttafuoco wrote: + +> create function abc() returns setof RECORD ... +> +> then to call it you would do +> select * from abc() as (a text,b int,...); +> +> +> +> +> ---------- Original Message ----------- +> From: Yves Vindevogel <yves.vindevogel@implements.be> +> To: pgsql-performance@postgresql.org +> Sent: Tue, 22 Nov 2005 19:29:37 +0100 +> Subject: [PERFORM] Stored Procedure +> +>> Is there another way in PG to return a recordset from a function than +>> to declare a type first ? +>> +>> create function fnTest () returns setof +>> myDefinedTypeIDontWantToDefineFirst ... +>> +>> Met vriendelijke groeten, +>> Bien =E0 vous, +>> Kind regards, +>> +>> Yves Vindevogel +>> Implements +> ------- End of Original Message ------- +> +> +> +Met vriendelijke groeten, +Bien =E0 vous, +Kind regards, + +Yves Vindevogel +Implements + + +--Apple-Mail-2--228161320 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/enriched; + charset=ISO-8859-1 + +But this does not work without the second line, right ? + +BTW, the thing returned is not a record. It's a bunch of fields, not +a complete record or fields of multiple records. + +I'm not so sure it works. + + +On 22 Nov 2005, at 19:42, Jim Buttafuoco wrote: + + +<excerpt>create function abc() returns setof RECORD ... + + +then to call it you would do + +select * from abc() as (a text,b int,...); + + + + + +---------- Original Message ----------- + +From: Yves Vindevogel <<yves.vindevogel@implements.be> + +To: pgsql-performance@postgresql.org + +Sent: Tue, 22 Nov 2005 19:29:37 +0100 + +Subject: [PERFORM] Stored Procedure + + +<excerpt>Is there another way in PG to return a recordset from a +function than=20 + +to declare a type first ? + + +create function fnTest () returns setof=20 + +myDefinedTypeIDontWantToDefineFirst ... + + +Met vriendelijke groeten, + +Bien =E0 vous, + +Kind regards, + + +Yves Vindevogel + +Implements + +</excerpt>------- End of Original Message ------- + + + + +</excerpt>Met vriendelijke groeten, + +Bien =E0 vous, + +Kind regards, + + +<bold>Yves 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- Mobile: +32 (478) 80 82 91 + +Kempische Steenweg 206 - 3500 Hasselt - Tel-Fax: +32 (11) 43 55 76 + +Web: http://www.implements.be + +First they ignore you. Then they laugh at you. Then they fight you. +Then you win. +Mahatma Ghandi. + +--Apple-Mail-3--228161319 +Content-Transfer-Encoding: 7bit +Content-Type: text/enriched; + charset=US-ASCII + +<smaller> + + +Mail: yves.vindevogel@implements.be - Mobile: +32 (478) 80 82 91 + + +Kempische Steenweg 206 - 3500 Hasselt - Tel-Fax: +32 (11) 43 55 76 + + +Web: http://www.implements.be + +<italic><x-tad-smaller> + +First they ignore you. Then they laugh at you. Then they fight you. +Then you win. + +Mahatma Ghandi.</x-tad-smaller></italic></smaller> + + +--Apple-Mail-3--228161319-- + +--Apple-Mail-1--228161321-- + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 18:52:21 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 49F34DBE02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 18:52:20 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 06924-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 22:52:21 +0000 (GMT) +X-Greylist: delayed 00:32:06.985064 by SQLgrey- +Received: from adicia.telenet-ops.be (adicia.telenet-ops.be [195.130.132.56]) + by svr1.postgresql.org (Postfix) with ESMTP id 49326DBDCD + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 18:52:16 -0400 (AST) +Received: from [10.0.1.2] (d5152B3BA.access.telenet.be [81.82.179.186]) + by adicia.telenet-ops.be (Postfix) with ESMTP id A363A380D9 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 23:20:10 +0100 (CET) +Mime-Version: 1.0 (Apple Message framework v623) +In-Reply-To: <20051122185941.GA18102@winnie.fuhr.org> +References: <e28aace15975ef9972fdd65ceb6e0ce8@implements.be> + <20051122185941.GA18102@winnie.fuhr.org> +Content-Type: multipart/mixed; boundary=Apple-Mail-4--228012768 +Message-Id: <06612338d301f531643d479a819e4632@implements.be> +From: Yves Vindevogel <yves.vindevogel@implements.be> +Subject: Re: Stored Procedure +Date: Tue, 22 Nov 2005 23:20:09 +0100 +To: pgsql-performance@postgresql.org +X-Mailer: Apple Mail (2.623) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.823 required=5 tests=[RCVD_IN_SORBS_SOCKS=1.823] +X-Spam-Score: 1.823 +X-Spam-Level: * +X-Archive-Number: 200511/459 +X-Sequence-Number: 15716 + + +--Apple-Mail-4--228012768 +Content-Type: multipart/alternative; + boundary=Apple-Mail-5--228012768 + + +--Apple-Mail-5--228012768 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/plain; + charset=ISO-8859-1; + format=flowed + +8.1, hmm, that's brand new. +But, still, it's quite some coding for a complete recordset, not ? + +On 22 Nov 2005, at 19:59, Michael Fuhr wrote: + +> On Tue, Nov 22, 2005 at 07:29:37PM +0100, Yves Vindevogel wrote: +>> Is there another way in PG to return a recordset from a function than +>> to declare a type first ? +> +> In 8.1 some languages support OUT and INOUT parameters. +> +> CREATE FUNCTION foo(IN x integer, INOUT y integer, OUT z integer) AS = +$$ +> BEGIN +> y :=3D y * 10; +> z :=3D x * 10; +> END; +> $$ LANGUAGE plpgsql IMMUTABLE STRICT; +> +> SELECT * FROM foo(1, 2); +> y | z +> ----+---- +> 20 | 10 +> (1 row) +> +> CREATE FUNCTION fooset(IN x integer, INOUT y integer, OUT z integer) +> RETURNS SETOF record AS $$ +> BEGIN +> y :=3D y * 10; +> z :=3D x * 10; +> RETURN NEXT; +> y :=3D y + 1; +> z :=3D z + 1; +> RETURN NEXT; +> END; +> $$ LANGUAGE plpgsql IMMUTABLE STRICT; +> +> SELECT * FROM fooset(1, 2); +> y | z +> ----+---- +> 20 | 10 +> 21 | 11 +> (2 rows) +> +> --=20 +> Michael Fuhr +> +> ---------------------------(end of=20 +> broadcast)--------------------------- +> TIP 4: Have you searched our list archives? +> +> http://archives.postgresql.org +> +> +Met vriendelijke groeten, +Bien =E0 vous, +Kind regards, + +Yves Vindevogel +Implements + + +--Apple-Mail-5--228012768 +Content-Transfer-Encoding: quoted-printable +Content-Type: text/enriched; + charset=ISO-8859-1 + +8.1, hmm, that's brand new. =20 + +But, still, it's quite some coding for a complete recordset, not ? + + +On 22 Nov 2005, at 19:59, Michael Fuhr wrote: + + +<excerpt>On Tue, Nov 22, 2005 at 07:29:37PM +0100, Yves Vindevogel +wrote: + +<excerpt>Is there another way in PG to return a recordset from a +function than=20 + +to declare a type first ?=20 + +</excerpt> + +In 8.1 some languages support OUT and INOUT parameters. + + +CREATE FUNCTION foo(IN x integer, INOUT y integer, OUT z integer) AS $$ + +BEGIN + + y :=3D y * 10; + + z :=3D x * 10; + +END; + +$$ LANGUAGE plpgsql IMMUTABLE STRICT; + + +SELECT * FROM foo(1, 2); + + y | z =20 + +----+---- + + 20 | 10 + +(1 row) + + +CREATE FUNCTION fooset(IN x integer, INOUT y integer, OUT z integer)=20 + +RETURNS SETOF record AS $$ + +BEGIN + + y :=3D y * 10; + + z :=3D x * 10; + + RETURN NEXT; + + y :=3D y + 1; + + z :=3D z + 1; + + RETURN NEXT; + +END; + +$$ LANGUAGE plpgsql IMMUTABLE STRICT; + + +SELECT * FROM fooset(1, 2); + + y | z =20 + +----+---- + + 20 | 10 + + 21 | 11 + +(2 rows) + + +--=20 + +Michael Fuhr + + +---------------------------(end of +broadcast)--------------------------- + +TIP 4: Have you searched our list archives? + + + http://archives.postgresql.org + + + +</excerpt>Met vriendelijke groeten, + +Bien =E0 vous, + +Kind regards, + + +<bold>Yves Vindevogel</bold> + +<bold>Implements</bold> + +<smaller> + +</smaller>= + +--Apple-Mail-5--228012768-- + +--Apple-Mail-4--228012768 +Content-Transfer-Encoding: base64 +Content-Type: image/tiff; + x-unix-mode=0666; + name="Pasted Graphic 2.tiff" +Content-Disposition: inline; + filename="Pasted Graphic 2.tiff" + +TU0AKgAAFciAP6BP5/wWDQeEQmFQuGQ2HQ+FP5+v9rOh5P9IMBuP8zK9tP8fJNlP8QoNjP8FndhP +8MnyVjJHSMrqFnv9BL1vP9ett2v98PuJxChUOiUWGQOCUalUujOV4PZ/qBluR/mdVtJ/jVHst/ho +9MF/g08WABHJfv8AWa0WoAHFfWuzgg6sB/hY9ysUohjv8qqVqv9LMZxv9ouV40zEYmHUjFY2HPx+ +RNtOl4Rhftt/phiRs6LC/iA5LewnJeWg46W22+02cAHOwa26bC0HPY7TZ7G2G9dv8EHFdP8Om9YP +8rKJov9UtFzv9Dzh/sRvu5/vZ9PzHdeF4zsUqgQRlOR5v9DMBwv8uqe/jZIVwNHu6B0/WAKHvWGr +RAA1ra0G1c/vfgANrdraXrTQIAA6JW2TUrQNz/ja0oAjO4YAjSWS0DOWawjys4RkIk4Lj2sAWEUZ +B/ieUJqH+PZdnAf5aG06R5nsfLtqW7UaoWZJwukwLyi4VRsn+F5HGYf8QJWBQ7JWAI5tYti2Dm1T +bQHAq0De1Q2FwtA1Fof4AjVDIBDQV0vDQWK0DY/oADYWsrNQN81NOuDZtYOM6ycs4Cjq+Q9JWE5D 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- Mobile: +32 (478) 80 82 91 + +Kempische Steenweg 206 - 3500 Hasselt - Tel-Fax: +32 (11) 43 55 76 + +Web: http://www.implements.be + +First they ignore you. Then they laugh at you. Then they fight you. +Then you win. +Mahatma Ghandi. + +--Apple-Mail-6--228012766 +Content-Transfer-Encoding: 7bit +Content-Type: text/enriched; + charset=US-ASCII + +<smaller> + + +Mail: yves.vindevogel@implements.be - Mobile: +32 (478) 80 82 91 + + +Kempische Steenweg 206 - 3500 Hasselt - Tel-Fax: +32 (11) 43 55 76 + + +Web: http://www.implements.be + +<italic><x-tad-smaller> + +First they ignore you. Then they laugh at you. Then they fight you. +Then you win. + +Mahatma Ghandi.</x-tad-smaller></italic></smaller> + + +--Apple-Mail-6--228012766-- + +--Apple-Mail-4--228012768-- + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 19:17:38 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 60D09DBE6E + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 19:17:37 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 12387-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 23:17:39 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from vt-pe2550-001.VANTAGE.vantage.com (unknown [64.80.203.244]) + by svr1.postgresql.org (Postfix) with ESMTP id 62D53DBE65 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 19:17:31 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.0.6249.0 +content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: High context switches occurring +Date: Tue, 22 Nov 2005 18:17:27 -0500 +Message-ID: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098E78@vt-pe2550-001.vantage.vantage.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] High context switches occurring +Thread-Index: AcXvpJzxdiGehd5LROOUKlr06FlV9AAEfAsA +From: "Anjan Dave" <adave@vantage.com> +To: "Scott Marlowe" <smarlowe@g2switchworks.com> +Cc: "Tom Lane" <tgl@sss.pgh.pa.us>, "Vivek Khera" <vivek@khera.org>, + "Postgresql Performance" <pgsql-performance@postgresql.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.359 required=5 tests=[AWL=-0.120, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.359 +X-Spam-Level: +X-Archive-Number: 200511/460 +X-Sequence-Number: 15717 + +Yes, it's turned on, unfortunately it got overlooked during the setup, +and until now...! + +It's mostly a 'read' application, I increased the vm.max-readahead to +2048 from the default 256, after which I've not seen the CS storm, +though it could be incidental. + +Thanks, +Anjan + +-----Original Message----- +From: Scott Marlowe [mailto:smarlowe@g2switchworks.com]=20 +Sent: Tuesday, November 22, 2005 3:38 PM +To: Anjan Dave +Cc: Tom Lane; Vivek Khera; Postgresql Performance +Subject: Re: [PERFORM] High context switches occurring + +On Tue, 2005-11-22 at 14:33, Anjan Dave wrote: +> Is there any way to get a temporary relief from this Context Switching +> storm? Does restarting postmaster help? +>=20 +> It seems that I can recreate the heavy CS with just one SELECT +> statement...and then when multiple such SELECT queries are coming in, +> things just get hosed up until we cancel a bunch of queries... + +Is your machine a hyperthreaded one? Some folks have found that turning +off hyper threading helps. I knew it made my servers better behaved in +the past. + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 20:13:38 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B9492DBF54 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 20:13:36 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 17556-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 00:13:37 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from candle.pha.pa.us (candle.pha.pa.us [64.139.89.126]) + by svr1.postgresql.org (Postfix) with ESMTP id 63745DBF44 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 20:13:31 -0400 (AST) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.11.6) id jAN0DKV10698; + Tue, 22 Nov 2005 19:13:20 -0500 (EST) +From: Bruce Momjian <pgman@candle.pha.pa.us> +Message-Id: <200511230013.jAN0DKV10698@candle.pha.pa.us> +Subject: Re: Hardware/OS recommendations for large databases ( +In-Reply-To: <87ek59omex.fsf@stark.xeocode.com> +To: Greg Stark <gsstark@mit.edu> +Date: Tue, 22 Nov 2005 19:13:20 -0500 (EST) +CC: stange@rentec.com, Luke Lonergan <llonergan@greenplum.com>, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +X-Mailer: ELM [version 2.4ME+ PL121 (25)] +MIME-Version: 1.0 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.028 required=5 tests=[AWL=0.028] +X-Spam-Score: 0.028 +X-Spam-Level: +X-Archive-Number: 200511/461 +X-Sequence-Number: 15718 + +Greg Stark wrote: +> +> Alan Stange <stange@rentec.com> writes: +> +> > The point your making doesn't match my experience with *any* storage or program +> > I've ever used, including postgresql. Your point suggests that the storage +> > system is idle and that postgresql is broken because it isn't able to use the +> > resources available...even when the cpu is very idle. How can that make sense? +> +> Well I think what he's saying is that Postgres is issuing a read, then waiting +> for the data to return. Then it does some processing, and goes back to issue +> another read. The CPU is idle half the time because Postgres isn't capable of +> doing any work while waiting for i/o, and the i/o system is idle half the time +> while the CPU intensive part happens. +> +> (Consider as a pathological example a program that reads 8k then sleeps for +> 10ms, and loops doing that 1,000 times. Now consider the same program +> optimized to read 8M asynchronously and sleep for 10s. By the time it's +> finished sleeping it has probably read in all 8M. Whereas the program that +> read 8k in little chunks interleaved with small sleeps would probably take +> twice as long and appear to be entirely i/o-bound with 50% iowait and 50% +> idle.) +> +> It's a reasonable theory and it's not inconsistent with the results you sent. +> But it's not exactly proven either. Nor is it clear how to improve matters. +> Adding additional threads to handle the i/o adds an enormous amount of +> complexity and creates lots of opportunity for other contention that could +> easily eat all of the gains. + +Perfect summary. We have a background writer now. Ideally we would +have a background reader, that reads-ahead blocks into the buffer cache. +The problem is that while there is a relatively long time between a +buffer being dirtied and the time it must be on disk (checkpoint time), +the read-ahead time is much shorter, requiring some kind of quick +"create a thread" approach that could easily bog us down as outlined +above. + +Right now the file system will do read-ahead for a heap scan (but not an +index scan), but even then, there is time required to get that kernel +block into the PostgreSQL shared buffers, backing up Luke's observation +of heavy memcpy() usage. + +So what are our options? mmap()? I have no idea. Seems larger page +size does help. + +-- + Bruce Momjian | http://candle.pha.pa.us + pgman@candle.pha.pa.us | (610) 359-1001 + + If your life is a hard drive, | 13 Roberts Road + + Christ can be your backup. | Newtown Square, Pennsylvania 19073 + +From pgsql-performance-owner@postgresql.org Tue Nov 22 23:39:07 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id EBFA2DBF66 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 23:39:04 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 58043-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 03:39:06 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from nz.telogis.com (unknown [203.98.10.169]) + by svr1.postgresql.org (Postfix) with ESMTP id 99B69DB8A5 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 23:39:00 -0400 (AST) +Received: from [192.168.3.1] ([192.168.3.1]) + by nz.telogis.com with esmtp; Wed, 23 Nov 2005 16:39:04 +1300 + id 007327AB.4383E458.000017DD +Message-ID: <4383E459.2070906@telogis.com> +Date: Wed, 23 Nov 2005 16:39:05 +1300 +From: Ralph Mason <ralph.mason@telogis.com> +User-Agent: Thunderbird 1.4 (Windows/20050908) +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Binary Refcursor possible? +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/462 +X-Sequence-Number: 15719 + +Hi, + +I am trying to get better performance reading data from postgres, so I +would like to return the data as binary rather than text as parsing it +is taking a considerable amount of processor. + +However I can't figure out how to do that! I have functions like. + +function my_func(ret refcursor) returns refcursor AS + +$$ + +BEGIN +OPEN $1 for select * from table; +return $1 +END; + +$$ language 'plpgsql' + +There are queried using + +SELECT my_func( 'ret'::refcursor); FETCH ALL FROM ret; + +Is there any way I can say make ret a binary cursor? + +Thanks +Ralph + + + +From pgsql-performance-owner@postgresql.org Tue Nov 22 23:58:59 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 110F5DAF8D + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 22 Nov 2005 23:58:58 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 61083-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 03:59:01 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id 06D68D9585 + for <pgsql-performance@postgresql.org>; + Tue, 22 Nov 2005 23:58:54 -0400 (AST) +Received: from wren.rentec.com (wren.rentec.com [192.5.35.106]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jAN3wKLm004749 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Tue, 22 Nov 2005 22:58:22 -0500 (EST) +X-Source: non-mednet +Received: from [172.16.160.106] (stangesun.rentec.com [172.16.160.106]) + by wren.rentec.com (8.13.1/8.12.1) with ESMTP id jAN3wNY5007526; + Tue, 22 Nov 2005 22:58:23 -0500 (EST) +Message-ID: <4383E89C.8040200@rentec.com> +Date: Tue, 22 Nov 2005 22:57:16 -0500 +From: Alan Stange <stange@rentec.com> +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Bruce Momjian <pgman@candle.pha.pa.us> +CC: Greg Stark <gsstark@mit.edu>, Luke Lonergan <llonergan@greenplum.com>, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <200511230013.jAN0DKV10698@candle.pha.pa.us> +In-Reply-To: <200511230013.jAN0DKV10698@candle.pha.pa.us> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jAN3wKLm004749 at Tue Nov 22 + 22:58:22 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.007 required=5 tests=[AWL=0.007] +X-Spam-Score: 0.007 +X-Spam-Level: +X-Archive-Number: 200511/463 +X-Sequence-Number: 15720 + +Bruce Momjian wrote: +> Greg Stark wrote: +> +>> Alan Stange <stange@rentec.com> writes: +>> +>> +>>> The point your making doesn't match my experience with *any* storage or program +>>> I've ever used, including postgresql. Your point suggests that the storage +>>> system is idle and that postgresql is broken because it isn't able to use the +>>> resources available...even when the cpu is very idle. How can that make sense? +>>> +>> Well I think what he's saying is that Postgres is issuing a read, then waiting +>> for the data to return. Then it does some processing, and goes back to issue +>> another read. The CPU is idle half the time because Postgres isn't capable of +>> doing any work while waiting for i/o, and the i/o system is idle half the time +>> while the CPU intensive part happens. +>> +>> (Consider as a pathological example a program that reads 8k then sleeps for +>> 10ms, and loops doing that 1,000 times. Now consider the same program +>> optimized to read 8M asynchronously and sleep for 10s. By the time it's +>> finished sleeping it has probably read in all 8M. Whereas the program that +>> read 8k in little chunks interleaved with small sleeps would probably take +>> twice as long and appear to be entirely i/o-bound with 50% iowait and 50% +>> idle.) +>> +>> It's a reasonable theory and it's not inconsistent with the results you sent. +>> But it's not exactly proven either. Nor is it clear how to improve matters. +>> Adding additional threads to handle the i/o adds an enormous amount of +>> complexity and creates lots of opportunity for other contention that could +>> easily eat all of the gains. +>> +> +> Perfect summary. We have a background writer now. Ideally we would +> have a background reader, that reads-ahead blocks into the buffer cache. +> The problem is that while there is a relatively long time between a +> buffer being dirtied and the time it must be on disk (checkpoint time), +> the read-ahead time is much shorter, requiring some kind of quick +> "create a thread" approach that could easily bog us down as outlined +> above. +> +> Right now the file system will do read-ahead for a heap scan (but not an +> index scan), but even then, there is time required to get that kernel +> block into the PostgreSQL shared buffers, backing up Luke's observation +> of heavy memcpy() usage. +> +> So what are our options? mmap()? I have no idea. Seems larger page +> size does help. +For sequential scans, you do have a background reader. It's the +kernel. As long as you don't issue a seek() between read() calls, the +kernel will get the hint about sequential IO and begin to perform a read +ahead for you. This is where the above analysis isn't quite right: +while postgresql is processing the returned data from the read() call, +the kernel has also issued reads as part of the read ahead, keeping the +device busy while the cpu is busy. (I'm assuming these details for +Linux; Solaris/UFS does work this way). Issue one seek on the file and +the read ahead algorithm will back off for a while. This was my point +about some descriptions of how the system works not being sensible. + +If your goal is sequential IO, then one must use larger block sizes. +No one would use 8KB IO for achieving high sequential IO rates. Simply +put, read() is about the slowest way to get 8KB of data. Switching +to 32KB blocks reduces all the system call overhead by a large margin. +Larger blocks would be better still, up to the stripe size of your +mirror. (Of course, you're using a mirror and not raid5 if you care +about performance.) + +I don't think the memcpy of data from the kernel to userspace is that +big of an issue right now. dd and all the high end network interfaces +manage OK doing it, so I'd expect postgresql to do all right with it now +yet too. Direct IO will avoid that memcpy, but then you also don't get +any caching of the files in memory. I'd be more concerned about any +memcpy calls or general data management within postgresql. Does +postgresql use the platform specific memcpy() in libc? Some care might +be needed to ensure that the memory blocks within postgresql are all +properly aligned to make sure that one isn't ping-ponging cache lines +around (usually done by padding the buffer sizes by an extra 32 bytes or +L1 line size). Whatever you do, all the usual high performance +computing tricks should be used prior to considering any rewriting of +major code sections. + +Personally, I'd like to see some detailed profiling being done using +hardware counters for cpu cycles and cache misses, etc. Given the poor +quality of work that has been discussed here in this thread, I don't +have much confidence in any other additional results at this time. +None of the analysis would be acceptable in any environment in which +I've worked. Be sure to take a look at Sun's free Workshop tools as +they are excellent for this sort of profiling and one doesn't need to +recompile to use them. If I get a little time in the next week or two +I might take a crack at this. + +Cheers, + +-- Alan + + +From pgsql-performance-owner@postgresql.org Wed Nov 23 00:07:30 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 37F90DAF8D + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 00:07:29 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 61176-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 04:07:27 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 8348AD9585 + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 00:07:26 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAN47PGj010136; + Tue, 22 Nov 2005 23:07:25 -0500 (EST) +To: Ralph Mason <ralph.mason@telogis.com> +cc: pgsql-performance@postgresql.org +Subject: Re: Binary Refcursor possible? +In-reply-to: <4383E459.2070906@telogis.com> +References: <4383E459.2070906@telogis.com> +Comments: In-reply-to Ralph Mason <ralph.mason@telogis.com> + message dated "Wed, 23 Nov 2005 16:39:05 +1300" +Date: Tue, 22 Nov 2005 23:07:25 -0500 +Message-ID: <10135.1132718845@sss.pgh.pa.us> +From: Tom Lane <tgl@sss.pgh.pa.us> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.004 required=5 tests=[AWL=0.004] +X-Spam-Score: 0.004 +X-Spam-Level: +X-Archive-Number: 200511/464 +X-Sequence-Number: 15721 + +Ralph Mason <ralph.mason@telogis.com> writes: +> Is there any way I can say make ret a binary cursor? + +It's possible to determine that at the protocol level, if you're using +V3 protocol; but whether this is exposed to an application depends on +what client-side software you are using. Which you didn't say. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Wed Nov 23 00:14:42 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 7A50DDC04F + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 00:14:41 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 61652-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 04:14:39 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from nz.telogis.com (unknown [203.98.10.169]) + by svr1.postgresql.org (Postfix) with ESMTP id D7FCDDC52E + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 00:14:38 -0400 (AST) +Received: from [192.168.3.1] ([192.168.3.1]) + by nz.telogis.com with esmtp; Wed, 23 Nov 2005 17:14:37 +1300 + id 007321A5.4383ECAD.00001865 +Message-ID: <4383ECAE.8050109@telogis.com> +Date: Wed, 23 Nov 2005 17:14:38 +1300 +From: Ralph Mason <ralph.mason@telogis.com> +User-Agent: Thunderbird 1.4 (Windows/20050908) +MIME-Version: 1.0 +To: Tom Lane <tgl@sss.pgh.pa.us> +CC: pgsql-performance@postgresql.org +Subject: Re: Binary Refcursor possible? +References: <4383E459.2070906@telogis.com> <10135.1132718845@sss.pgh.pa.us> +In-Reply-To: <10135.1132718845@sss.pgh.pa.us> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/465 +X-Sequence-Number: 15722 + +Tom Lane wrote: +> Ralph Mason <ralph.mason@telogis.com> writes: +> +>> Is there any way I can say make ret a binary cursor? +>> +> +> It's possible to determine that at the protocol level, if you're using +> V3 protocol; but whether this is exposed to an application depends on +> what client-side software you are using. Which you didn't say. +> +> regards, tom lane +> +This is probably in the documentation but I couldn't find it. + +All I could see is that if you open a cursor for binary it would return +with a type of binary rather than text in the row data messages. The +RowDescription format code is always text, and the cursor thing is the +only way I could see to change that. + +Is there some setting I can set that will make it return all data as +binary? The dream would also be that I could ask the server it's native +byte order and have it send me binary data in it's native byte order. +Nice and fast. :-0 + +Ralph + + + + + +From pgsql-performance-owner@postgresql.org Wed Nov 23 00:21:50 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id C97B4DB1EE + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 00:21:49 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 65817-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 04:21:47 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from stark.xeocode.com (stark.xeocode.com [216.58.44.227]) + by svr1.postgresql.org (Postfix) with ESMTP id 8E0C4DB1C7 + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 00:21:46 -0400 (AST) +Received: from localhost ([127.0.0.1] helo=stark.xeocode.com) + by stark.xeocode.com with smtp (Exim 3.36 #1 (Debian)) + id 1Eem8X-0003Yu-00; Tue, 22 Nov 2005 23:21:37 -0500 +To: Alan Stange <stange@rentec.com> +Cc: Bruce Momjian <pgman@candle.pha.pa.us>, Greg Stark <gsstark@mit.edu>, + Luke Lonergan <llonergan@greenplum.com>, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <200511230013.jAN0DKV10698@candle.pha.pa.us> + <4383E89C.8040200@rentec.com> +In-Reply-To: <4383E89C.8040200@rentec.com> +From: Greg Stark <gsstark@mit.edu> +Organization: The Emacs Conspiracy; member since 1992 +Date: 22 Nov 2005 23:21:36 -0500 +Message-ID: <87d5ksm1tb.fsf@stark.xeocode.com> +Lines: 54 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/466 +X-Sequence-Number: 15723 + + +Alan Stange <stange@rentec.com> writes: + +> For sequential scans, you do have a background reader. It's the kernel. As +> long as you don't issue a seek() between read() calls, the kernel will get the +> hint about sequential IO and begin to perform a read ahead for you. This is +> where the above analysis isn't quite right: while postgresql is processing the +> returned data from the read() call, the kernel has also issued reads as part of +> the read ahead, keeping the device busy while the cpu is busy. (I'm assuming +> these details for Linux; Solaris/UFS does work this way). Issue one seek on +> the file and the read ahead algorithm will back off for a while. This was my +> point about some descriptions of how the system works not being sensible. + +Well that's certainly the hope. But we don't know that this is actually as +effective as you assume it is. It's awfully hard in the kernel to make much +more than a vague educated guess about what kind of readahead would actually +help. + +This is especially true when a file isn't really being accessed in a +sequential fashion as Postgres may well do if, for example, multiple backends +are reading the same file. And as you pointed out it doesn't help at all for +random access index scans. + +> If your goal is sequential IO, then one must use larger block sizes. No one +> would use 8KB IO for achieving high sequential IO rates. Simply put, read() +> is about the slowest way to get 8KB of data. Switching to 32KB blocks +> reduces all the system call overhead by a large margin. Larger blocks would be +> better still, up to the stripe size of your mirror. (Of course, you're using +> a mirror and not raid5 if you care about performance.) + +Switching to 32kB blocks throughout Postgres has pros but also major cons, not +the least is *extra* i/o for random access read patterns. One of the possible +advantages of the suggestions that were made, the ones you're shouting down, +would actually be the ability to use 32kB scatter/gather reads without +necessarily switching block sizes. + +(Incidentally, your parenthetical comment is a bit confused. By "mirror" I +imagine you're referring to raid1+0 since mirrors alone, aka raid1, aren't a +popular way to improve performance. But raid5 actually performs better than +raid1+0 for sequential reads.) + +> Does postgresql use the platform specific memcpy() in libc? Some care might +> be needed to ensure that the memory blocks within postgresql are all +> properly aligned to make sure that one isn't ping-ponging cache lines around +> (usually done by padding the buffer sizes by an extra 32 bytes or L1 line +> size). Whatever you do, all the usual high performance computing tricks +> should be used prior to considering any rewriting of major code sections. + +So your philosophy is to worry about microoptimizations before worrying about +architectural issues? + + +-- +greg + + +From pgsql-performance-owner@postgresql.org Wed Nov 23 00:53:40 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id DAF4ADA135 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 00:53:39 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 67139-09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 04:53:38 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from candle.pha.pa.us (candle.pha.pa.us [64.139.89.126]) + by svr1.postgresql.org (Postfix) with ESMTP id CB893D9585 + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 00:53:36 -0400 (AST) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.11.6) id jAN4rGs24421; + Tue, 22 Nov 2005 23:53:16 -0500 (EST) +From: Bruce Momjian <pgman@candle.pha.pa.us> +Message-Id: <200511230453.jAN4rGs24421@candle.pha.pa.us> +Subject: Re: Hardware/OS recommendations for large databases ( +In-Reply-To: <4383E89C.8040200@rentec.com> +To: Alan Stange <stange@rentec.com> +Date: Tue, 22 Nov 2005 23:53:16 -0500 (EST) +CC: Greg Stark <gsstark@mit.edu>, Luke Lonergan <llonergan@greenplum.com>, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +X-Mailer: ELM [version 2.4ME+ PL121 (25)] +MIME-Version: 1.0 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.026 required=5 tests=[AWL=0.026] +X-Spam-Score: 0.026 +X-Spam-Level: +X-Archive-Number: 200511/467 +X-Sequence-Number: 15724 + +Alan Stange wrote: +> Bruce Momjian wrote: +> > Right now the file system will do read-ahead for a heap scan (but not an +> > index scan), but even then, there is time required to get that kernel +> > block into the PostgreSQL shared buffers, backing up Luke's observation +> > of heavy memcpy() usage. +> > +> > So what are our options? mmap()? I have no idea. Seems larger page +> > size does help. + +> For sequential scans, you do have a background reader. It's the +> kernel. As long as you don't issue a seek() between read() calls, the + +I guess you missed my text of "Right now the file system will do +read-ahead", meaning the kernel. + +> I don't think the memcpy of data from the kernel to userspace is that +> big of an issue right now. dd and all the high end network interfaces +> manage OK doing it, so I'd expect postgresql to do all right with it now +> yet too. Direct IO will avoid that memcpy, but then you also don't get +> any caching of the files in memory. I'd be more concerned about any +> memcpy calls or general data management within postgresql. Does +> postgresql use the platform specific memcpy() in libc? Some care might +> be needed to ensure that the memory blocks within postgresql are all +> properly aligned to make sure that one isn't ping-ponging cache lines +> around (usually done by padding the buffer sizes by an extra 32 bytes or +> L1 line size). Whatever you do, all the usual high performance +> computing tricks should be used prior to considering any rewriting of +> major code sections. + +We have dealt with alignment and MemCpy is what we used for small-sized +copies to reduce function call overhead. If you want to improve it, +feel free to take a look. + +-- + Bruce Momjian | http://candle.pha.pa.us + pgman@candle.pha.pa.us | (610) 359-1001 + + If your life is a hard drive, | 13 Roberts Road + + Christ can be your backup. | Newtown Square, Pennsylvania 19073 + +From pgsql-performance-owner@postgresql.org Wed Nov 23 01:05:29 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 80B84D8292 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 01:05:28 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 75266-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 05:05:27 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from tigger.fuhr.org (tigger.fuhr.org [63.214.45.158]) + by svr1.postgresql.org (Postfix) with ESMTP id D12E2D80BC + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 01:05:25 -0400 (AST) +Received: from winnie.fuhr.org (winnie.fuhr.org [10.1.0.1]) + by tigger.fuhr.org (8.13.3/8.13.3) with ESMTP id jAN55I0r057016 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); + Tue, 22 Nov 2005 22:05:21 -0700 (MST) + (envelope-from mfuhr@winnie.fuhr.org) +Received: from winnie.fuhr.org (localhost [127.0.0.1]) + by winnie.fuhr.org (8.13.4/8.13.4) with ESMTP id jAN55Idq049141; + Tue, 22 Nov 2005 22:05:18 -0700 (MST) + (envelope-from mfuhr@winnie.fuhr.org) +Received: (from mfuhr@localhost) + by winnie.fuhr.org (8.13.4/8.13.4/Submit) id jAN55Hrj049140; + Tue, 22 Nov 2005 22:05:17 -0700 (MST) (envelope-from mfuhr) +Date: Tue, 22 Nov 2005 22:05:17 -0700 +From: Michael Fuhr <mike@fuhr.org> +To: Yves Vindevogel <yves.vindevogel@implements.be> +Cc: pgsql-performance@postgresql.org +Subject: Re: Stored Procedure +Message-ID: <20051123050517.GA49008@winnie.fuhr.org> +References: <e28aace15975ef9972fdd65ceb6e0ce8@implements.be> + <20051122184119.M48526@contactbda.com> + <33f74d2a046b89d119c349e82b7398de@implements.be> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <33f74d2a046b89d119c349e82b7398de@implements.be> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/468 +X-Sequence-Number: 15725 + +On Tue, Nov 22, 2005 at 11:17:41PM +0100, Yves Vindevogel wrote: +> But this does not work without the second line, right ? + +What second line? Instead of returning a specific composite type +a function can return RECORD or SETOF RECORD; in these cases the +query must provide a column definition list. + +> BTW, the thing returned is not a record. It's a bunch of fields, not a +> complete record or fields of multiple records. + +What distinction are you making between a record and a bunch of +fields? What exactly would you like the function to return? + +> I'm not so sure it works. + +Did you try it? If you did and it didn't work then please post +exactly what you tried and explain what happened and how that +differed from what you'd like. + +-- +Michael Fuhr + +From pgsql-performance-owner@postgresql.org Wed Nov 23 01:13:22 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5500AD6D07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 01:13:22 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 81019-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 05:13:20 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from tigger.fuhr.org (tigger.fuhr.org [63.214.45.158]) + by svr1.postgresql.org (Postfix) with ESMTP id 95940D7E05 + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 01:13:19 -0400 (AST) +Received: from winnie.fuhr.org (winnie.fuhr.org [10.1.0.1]) + by tigger.fuhr.org (8.13.3/8.13.3) with ESMTP id jAN5DEpb057022 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); + Tue, 22 Nov 2005 22:13:16 -0700 (MST) + (envelope-from mfuhr@winnie.fuhr.org) +Received: from winnie.fuhr.org (localhost [127.0.0.1]) + by winnie.fuhr.org (8.13.4/8.13.4) with ESMTP id jAN5DEXd049202; + Tue, 22 Nov 2005 22:13:14 -0700 (MST) + (envelope-from mfuhr@winnie.fuhr.org) +Received: (from mfuhr@localhost) + by winnie.fuhr.org (8.13.4/8.13.4/Submit) id jAN5DE0t049201; + Tue, 22 Nov 2005 22:13:14 -0700 (MST) (envelope-from mfuhr) +Date: Tue, 22 Nov 2005 22:13:14 -0700 +From: Michael Fuhr <mike@fuhr.org> +To: Yves Vindevogel <yves.vindevogel@implements.be> +Cc: pgsql-performance@postgresql.org +Subject: Re: Stored Procedure +Message-ID: <20051123051314.GB49008@winnie.fuhr.org> +References: <e28aace15975ef9972fdd65ceb6e0ce8@implements.be> + <20051122185941.GA18102@winnie.fuhr.org> + <06612338d301f531643d479a819e4632@implements.be> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <06612338d301f531643d479a819e4632@implements.be> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/469 +X-Sequence-Number: 15726 + +On Tue, Nov 22, 2005 at 11:20:09PM +0100, Yves Vindevogel wrote: +> 8.1, hmm, that's brand new. + +Yes, but give it a try, at least in a test environment. The more +people use it, the more we'll find out if it has any problems. + +> But, still, it's quite some coding for a complete recordset, not ? + +How so? The examples I posted are almost identical to how you'd +return a composite type created with CREATE TYPE or SETOF that type, +except that you declare the return columns as INOUT or OUT parameters +and you no longer have to create a separate type. If you're referring +to how I wrote two sets of assignments and RETURN NEXT statements, +you don't have to do it that way: you can use a loop, just as you +would with any other set-returning function. + +-- +Michael Fuhr + +From pgsql-performance-owner@postgresql.org Wed Nov 23 13:51:45 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 44449DBA49 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 13:51:44 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 49347-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 17:51:42 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw03.mi8.com [63.240.6.42]) + by svr1.postgresql.org (Postfix) with ESMTP id 330A6DBA1E + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 13:51:40 -0400 (AST) +Received: from 172.16.1.110 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D3)); Wed, 23 Nov 2005 12:51:32 -0500 +X-Server-Uuid: E847189C-FC88-4913-9CD4-DE66914F83C0 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Wed, 23 Nov + 2005 12:51:08 -0500 +Received: from 208.54.15.129 ([208.54.15.129]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.106]) with Microsoft Exchange Server HTTP-DAV ; Wed, 23 Nov + 2005 12:51:08 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Wed, 23 Nov 2005 09:51:06 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Bruce Momjian" <pgman@candle.pha.pa.us>, + "Greg Stark" <gsstark@mit.edu> +cc: stange@rentec.com, "Dave Cramer" <pg@fastcrypt.com>, + "Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-ID: <BFA9EC0A.14580%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXvwsL8LhmQH2wmSB604BAv4GFvlwAk7dXr +In-Reply-To: <200511230013.jAN0DKV10698@candle.pha.pa.us> +MIME-Version: 1.0 +X-OriginalArrivalTime: 23 Nov 2005 17:51:08.0974 (UTC) + FILETIME=[7C182CE0:01C5F056] +X-WSS-ID: 6F9A73A819O1733739-18-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=2.386 required=5 tests=[AWL=-0.103, + RCVD_IN_SORBS_WEB=1.236, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 2.386 +X-Spam-Level: ** +X-Archive-Number: 200511/470 +X-Sequence-Number: 15727 + +Bruce, + +On 11/22/05 4:13 PM, "Bruce Momjian" <pgman@candle.pha.pa.us> wrote: + +> Perfect summary. We have a background writer now. Ideally we would +> have a background reader, that reads-ahead blocks into the buffer cache. +> The problem is that while there is a relatively long time between a +> buffer being dirtied and the time it must be on disk (checkpoint time), +> the read-ahead time is much shorter, requiring some kind of quick +> "create a thread" approach that could easily bog us down as outlined +> above. + +Yes, the question is "how much read-ahead buffer is needed to equate to the +38% of I/O wait time in the current executor profile?" + +The idea of asynchronous buffering would seem appropriate if the executor +would use the 38% of time as useful work. + +A background reader is an interesting approach - it would require admin +management of buffers where AIO would leave that in the kernel. The +advantage over AIO would be more universal platform support I suppose? + +> Right now the file system will do read-ahead for a heap scan (but not an +> index scan), but even then, there is time required to get that kernel +> block into the PostgreSQL shared buffers, backing up Luke's observation +> of heavy memcpy() usage. + +As evidenced by the 16MB readahead setting still resulting in only 36% IO +wait. + +> So what are our options? mmap()? I have no idea. Seems larger page +> size does help. + +Not sure about that, we used to run with 32KB page size and I didn't see a +benefit on seq scan at all. I haven't seen tests in this thread that +compare 8K to 32K. + +- Luke + + + +From pgsql-performance-owner@postgresql.org Wed Nov 23 13:54:03 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 27C3ED7AD7 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 13:54:03 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 49888-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 17:54:01 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw03.mi8.com [63.240.6.42]) + by svr1.postgresql.org (Postfix) with ESMTP id 162E3DBA50 + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 13:53:59 -0400 (AST) +Received: from 172.16.1.112 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D3)); Wed, 23 Nov 2005 12:53:52 -0500 +X-Server-Uuid: E847189C-FC88-4913-9CD4-DE66914F83C0 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Wed, 23 Nov + 2005 12:53:09 -0500 +Received: from 208.54.15.129 ([208.54.15.129]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.106]) with Microsoft Exchange Server HTTP-DAV ; Wed, 23 Nov + 2005 12:53:08 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Wed, 23 Nov 2005 09:53:04 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Alan Stange" <stange@rentec.com>, + "Postgresql Performance" <pgsql-performance@postgresql.org> +Message-ID: <BFA9EC80.14581%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXv4jqsmv9TrNIXTUGC/P0cEau11wAdIX6t +In-Reply-To: <4383E89C.8040200@rentec.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 23 Nov 2005 17:53:09.0510 (UTC) + FILETIME=[C3F08260:01C5F056] +X-WSS-ID: 6F9A732719O1735241-30-01 +Content-Type: multipart/alternative; + boundary=B_3215584385_16349364 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=2.401 required=5 tests=[AWL=-0.089, + HTML_MESSAGE=0.001, RCVD_IN_SORBS_WEB=1.236, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 2.401 +X-Spam-Level: ** +X-Archive-Number: 200511/471 +X-Sequence-Number: 15728 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3215584385_16349364 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit + +Alan, + +Why not contribute something - put up proof of your stated 8KB versus 32KB +page size improvement. + +- Luke + +--B_3215584385_16349364 +Content-Type: text/html; + charset=us-ascii +Content-Transfer-Encoding: quoted-printable + +<HTML> +<HEAD> +<TITLE>Re: [PERFORM] Hardware/OS recommendations for large databases (</TIT= +LE> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Alan,= +<BR> +<BR> +Why not contribute something - put up proof of your stated 8KB versus 32KB = +page size improvement.<BR> +<BR> +- Luke</SPAN></FONT> +</BODY> +</HTML> + + +--B_3215584385_16349364-- + + +From pgsql-performance-owner@postgresql.org Wed Nov 23 14:15:06 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0B145DBA7B + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 14:15:05 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 50188-07-2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 18:15:00 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtp.nildram.co.uk (smtp.nildram.co.uk [195.112.4.54]) + by svr1.postgresql.org (Postfix) with ESMTP id 1F8E6DBA81 + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 14:14:56 -0400 (AST) +Received: from [192.168.0.4] (unknown [84.12.200.148]) + by smtp.nildram.co.uk (Postfix) with ESMTP + id 8E25825E762; Wed, 23 Nov 2005 18:14:50 +0000 (GMT) +Subject: Re: High context switches occurring +From: Simon Riggs <simon@2ndquadrant.com> +To: Anjan Dave <adave@vantage.com> +Cc: Scott Marlowe <smarlowe@g2switchworks.com>, + Tom Lane <tgl@sss.pgh.pa.us>, Vivek Khera <vivek@khera.org>, + Postgresql Performance <pgsql-performance@postgresql.org> +In-Reply-To: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098E78@vt-pe2550-001.vantage.vantage.com> +References: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098E78@vt-pe2550-001.vantage.vantage.com> +Content-Type: text/plain +Date: Wed, 23 Nov 2005 18:13:58 +0000 +Message-Id: <1132769638.4347.7.camel@localhost.localdomain> +Mime-Version: 1.0 +X-Mailer: Evolution 2.2.2 (2.2.2-5) +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/472 +X-Sequence-Number: 15729 + +On Tue, 2005-11-22 at 18:17 -0500, Anjan Dave wrote: + +> It's mostly a 'read' application, I increased the vm.max-readahead to +> 2048 from the default 256, after which I've not seen the CS storm, +> though it could be incidental. + +Can you verify this, please? + +Turn it back down again, try the test, then reset and try the test. + +If that is a repeatable way of recreating one manifestation of the +problem then we will be further ahead than we are now. + +Thanks, + +Best Regards, Simon Riggs + + +From pgsql-performance-owner@postgresql.org Wed Nov 23 14:33:18 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 86D4AD8A19 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 14:33:17 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 53119-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 18:33:16 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from vt-pe2550-001.VANTAGE.vantage.com (unknown [64.80.203.244]) + by svr1.postgresql.org (Postfix) with ESMTP id 52DB9D7AD7 + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 14:33:13 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.0.6249.0 +content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: High context switches occurring +Date: Wed, 23 Nov 2005 13:33:09 -0500 +Message-ID: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098E7B@vt-pe2550-001.vantage.vantage.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] High context switches occurring +Thread-Index: AcXwWdTR75D6bDAeR6S1VGqN2qlaJAAABtFg +From: "Anjan Dave" <adave@vantage.com> +To: "Simon Riggs" <simon@2ndquadrant.com> +Cc: "Scott Marlowe" <smarlowe@g2switchworks.com>, + "Tom Lane" <tgl@sss.pgh.pa.us>, "Vivek Khera" <vivek@khera.org>, + "Postgresql Performance" <pgsql-performance@postgresql.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.359 required=5 tests=[AWL=-0.120, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.359 +X-Spam-Level: +X-Archive-Number: 200511/473 +X-Sequence-Number: 15730 + +The offending SELECT query that invoked the CS storm was optimized by +folks here last night, so it's hard to say if the VM setting made a +difference. I'll give it a try anyway. + +Thanks, +Anjan + +-----Original Message----- +From: Simon Riggs [mailto:simon@2ndquadrant.com]=20 +Sent: Wednesday, November 23, 2005 1:14 PM +To: Anjan Dave +Cc: Scott Marlowe; Tom Lane; Vivek Khera; Postgresql Performance +Subject: Re: [PERFORM] High context switches occurring + +On Tue, 2005-11-22 at 18:17 -0500, Anjan Dave wrote: + +> It's mostly a 'read' application, I increased the vm.max-readahead to +> 2048 from the default 256, after which I've not seen the CS storm, +> though it could be incidental. + +Can you verify this, please? + +Turn it back down again, try the test, then reset and try the test. + +If that is a repeatable way of recreating one manifestation of the +problem then we will be further ahead than we are now. + +Thanks, + +Best Regards, Simon Riggs + + + +From pgsql-performance-owner@postgresql.org Wed Nov 23 17:33:31 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A38FADBA31 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 17:33:30 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 49953-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 21:33:31 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from vt-pe2550-001.VANTAGE.vantage.com (unknown [64.80.203.244]) + by svr1.postgresql.org (Postfix) with ESMTP id 96990DAF10 + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 17:33:26 -0400 (AST) +X-MimeOLE: Produced By Microsoft Exchange V6.0.6249.0 +content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: High context switches occurring +Date: Wed, 23 Nov 2005 16:33:24 -0500 +Message-ID: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785027001E7@vt-pe2550-001.vantage.vantage.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] High context switches occurring +Thread-Index: AcXwWdTR75D6bDAeR6S1VGqN2qlaJAAABtFgAAbJl0A= +From: "Anjan Dave" <adave@vantage.com> +To: "Anjan Dave" <adave@vantage.com>, + "Simon Riggs" <simon@2ndquadrant.com> +Cc: "Scott Marlowe" <smarlowe@g2switchworks.com>, + "Tom Lane" <tgl@sss.pgh.pa.us>, "Vivek Khera" <vivek@khera.org>, + "Postgresql Performance" <pgsql-performance@postgresql.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.359 required=5 tests=[AWL=-0.120, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.359 +X-Spam-Level: +X-Archive-Number: 200511/474 +X-Sequence-Number: 15731 + +Simon, + +I tested it by running two of those simultaneous queries (the +'unoptimized' one), and it doesn't make any difference whether +vm.max-readahead is 256 or 2048...the modified query runs in a snap. + +Thanks, +Anjan + +-----Original Message----- +From: Anjan Dave=20 +Sent: Wednesday, November 23, 2005 1:33 PM +To: Simon Riggs +Cc: Scott Marlowe; Tom Lane; Vivek Khera; Postgresql Performance +Subject: Re: [PERFORM] High context switches occurring + +The offending SELECT query that invoked the CS storm was optimized by +folks here last night, so it's hard to say if the VM setting made a +difference. I'll give it a try anyway. + +Thanks, +Anjan + +-----Original Message----- +From: Simon Riggs [mailto:simon@2ndquadrant.com]=20 +Sent: Wednesday, November 23, 2005 1:14 PM +To: Anjan Dave +Cc: Scott Marlowe; Tom Lane; Vivek Khera; Postgresql Performance +Subject: Re: [PERFORM] High context switches occurring + +On Tue, 2005-11-22 at 18:17 -0500, Anjan Dave wrote: + +> It's mostly a 'read' application, I increased the vm.max-readahead to +> 2048 from the default 256, after which I've not seen the CS storm, +> though it could be incidental. + +Can you verify this, please? + +Turn it back down again, try the test, then reset and try the test. + +If that is a repeatable way of recreating one manifestation of the +problem then we will be further ahead than we are now. + +Thanks, + +Best Regards, Simon Riggs + + + +---------------------------(end of broadcast)--------------------------- +TIP 6: explain analyze is your friend + + +From pgsql-performance-owner@postgresql.org Wed Nov 23 18:00:43 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D26D7DBA92 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 18:00:42 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 80479-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 22:00:44 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from unicorn.rentec.com (unicorn.rentec.com [216.223.240.9]) + by svr1.postgresql.org (Postfix) with ESMTP id 268D9DBA4E + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 18:00:39 -0400 (AST) +Received: from wren.rentec.com (wren.rentec.com [192.5.35.106]) + by unicorn.rentec.com (8.13.1/8.12.1) with ESMTP id jANM0T2v021183 + (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); + Wed, 23 Nov 2005 17:00:30 -0500 (EST) +X-Source: non-mednet +Received: from [172.26.132.145] (hoopoe.rentec.com [172.26.132.145]) + by wren.rentec.com (8.13.1/8.12.1) with ESMTP id jANM0ZvF014858; + Wed, 23 Nov 2005 17:00:35 -0500 (EST) +Message-ID: <4384E685.4060108@rentec.com> +Date: Wed, 23 Nov 2005 17:00:37 -0500 +From: Alan Stange <stange@rentec.com> +Reply-To: stange@rentec.com +Organization: Renaissance Technologies Corp. +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Luke Lonergan <llonergan@greenplum.com> +CC: Postgresql Performance <pgsql-performance@postgresql.org> +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFA9EC80.14581%llonergan@greenplum.com> +In-Reply-To: <BFA9EC80.14581%llonergan@greenplum.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Logged: Logged by unicorn.rentec.com as jANM0T2v021183 at Wed Nov 23 + 17:00:30 2005 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.007 required=5 tests=[AWL=0.007] +X-Spam-Score: 0.007 +X-Spam-Level: +X-Archive-Number: 200511/475 +X-Sequence-Number: 15732 + +Luke Lonergan wrote: +> Why not contribute something - put up proof of your stated 8KB versus +> 32KB page size improvement. + +I did observe that 32KB block sizes were a significant win "for our +usage patterns". It might be a win for any of the following reasons: + +0) The preliminaries: ~300GB database with about ~50GB daily +turnover. Our data is fairly reasonably grouped. If we're getting one +item on a page we're usually looking at the other items as well. + +1) we can live with a smaller FSM size. We were often leaking pages +with a 10M page FSM setting. With 32K pages, a 10M FSM size is +sufficient. Yes, the solution to this is "run vacuum more often", but +when the vacuum was taking 10 hours at a time, that was hard to do. + +2) The typical datum size in our largest table is about 2.8KB, which is +more than 1/4 page size thus resulting in the use of a toast table. +Switching to 32KB pages allows us to get a decent storage of this data +into the main tables, thus avoiding another table and associated large +index. Not having the extra index in memory for a table with 90M rows +is probably beneficial. + +3) vacuum time has been substantially reduced. Vacuum analyze now run +in the 2 to 3 hour range depending on load. + +4) less cpu time spent in the kernel. We're basically doing 1/4 as many +system calls. + +Overall the system has now been working well. We used to see the +database being a bottleneck at times, but now it's keeping up nicely. + +Hope this helps. + +Happy Thanksgiving! + +-- Alan + +From pgsql-performance-owner@postgresql.org Wed Nov 23 21:23:56 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 395B3DBAF8 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 21:23:54 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14770-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 01:23:56 +0000 (GMT) +X-Greylist: delayed 03:08:37.873948 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 1E678DBAC1 + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 21:23:50 -0400 (AST) +Received: from mail.rilk.com (mail.rilk.com [193.19.217.130]) + by svr2.postgresql.org (Postfix) with ESMTP id 70A87F0B82 + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 22:15:14 +0000 (GMT) +Received: from [192.168.0.1] (cev75-1-81-57-249-136.fbx.proxad.net + [81.57.249.136]) (authenticated bits=0) + by mail.rilk.com (8.13.0/8.13.0) with ESMTP id jANMEmM6016783 + (version=TLSv1/SSLv3 cipher=EDH-DSS-DES-CBC3-SHA bits=168 verify=NO) + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 23:15:02 +0100 (CET) +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Transfer-Encoding: quoted-printable +Message-Id: <334D9941-B5B3-4D18-8312-F85D0FB054ED@rilk.com> +Content-Type: text/plain; charset=ISO-8859-1; delsp=yes; format=flowed +To: pgsql-performance@postgresql.org +From: Pailloncy Jean-Gerard <jg@rilk.com> +Subject: 8.1 count(*) distinct: IndexScan/SeqScan +Date: Wed, 23 Nov 2005 23:14:47 +0100 +X-Mailer: Apple Mail (2.746.2) +X-DCC-dmv.com-Metrics: mail.rilk.com 1181; Body=1 Fuz1=1 Fuz2=1 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/476 +X-Sequence-Number: 15733 + +Hi, + +PostgreSQL 8.1 fresh install on a freshly installed OpenBSD 3.8 box. + +postgres=3D# CREATE DATABASE test; +CREATE DATABASE +postgres=3D# create table test (id serial, val integer); +NOTICE: CREATE TABLE will create implicit sequence "test_id_seq" for =20= + +serial column "test.id" +CREATE TABLE +postgres=3D# create unique index testid on test (id); +CREATE INDEX +postgres=3D# create index testval on test (val); +CREATE INDEX +postgres=3D# insert into test (val) values (round(random()=20 +*1024*1024*1024)); +INSERT 0 1 + +[...] insert many random values + +postgres=3D# vaccum full verbose analyze; +postgres=3D# select count(1) from test; + count +--------- +2097152 +(1 row) + +postgres=3D# explain select count(*) from (select distinct on (val) * =20= + +from test) as foo; + QUERY PLAN +------------------------------------------------------------------------=20= + +------------------ +Aggregate (cost=3D66328.72..66328.73 rows=3D1 width=3D0) + -> Unique (cost=3D0.00..40114.32 rows=3D2097152 width=3D8) + -> Index Scan using testval on test (cost=3D0.00..34871.44 =20= + +rows=3D2097152 width=3D8) +(3 rows) + +postgres=3D# set enable_indexscan=3Doff; +postgres=3D# explain analyze select count(*) from (select distinct on =20= + +(val) * from test) as foo; + QUERY PLAN +------------------------------------------------------------------------=20= + +------------------------------------------------------------ +Aggregate (cost=3D280438.64..280438.65 rows=3D1 width=3D0) (actual =20 +time=3D39604.107..39604.108 rows=3D1 loops=3D1) + -> Unique (cost=3D243738.48..254224.24 rows=3D2097152 width=3D8) =20= + +(actual time=3D30281.004..37746.488 rows=3D2095104 loops=3D1) + -> Sort (cost=3D243738.48..248981.36 rows=3D2097152 width=3D8)= + =20 +(actual time=3D30280.999..33744.197 rows=3D2097152 loops=3D1) + Sort Key: test.val + -> Seq Scan on test (cost=3D0.00..23537.52 =20 +rows=3D2097152 width=3D8) (actual time=3D11.550..3262.433 rows=3D2097152 = +=20 +loops=3D1) +Total runtime: 39624.094 ms +(6 rows) + +postgres=3D# set enable_indexscan=3Don; +postgres=3D# explain analyze select count(*) from (select distinct on =20= + +(val) * from test where val<10000000) as foo; + =20 +QUERY PLAN +------------------------------------------------------------------------=20= + +----------------------------------------------------------------------- +Aggregate (cost=3D4739.58..4739.59 rows=3D1 width=3D0) (actual =20 +time=3D4686.472..4686.473 rows=3D1 loops=3D1) + -> Unique (cost=3D4380.56..4483.14 rows=3D20515 width=3D8) (actual = +=20 +time=3D4609.046..4669.289 rows=3D19237 loops=3D1) + -> Sort (cost=3D4380.56..4431.85 rows=3D20515 width=3D8) =20 +(actual time=3D4609.041..4627.976 rows=3D19255 loops=3D1) + Sort Key: test.val + -> Bitmap Heap Scan on test (cost=3D88.80..2911.24 =20 +rows=3D20515 width=3D8) (actual time=3D130.954..4559.244 rows=3D19255 = +loops=3D1) + Recheck Cond: (val < 10000000) + -> Bitmap Index Scan on testval =20 +(cost=3D0.00..88.80 rows=3D20515 width=3D0) (actual = +time=3D120.041..120.041 =20 +rows=3D19255 loops=3D1) + Index Cond: (val < 10000000) +Total runtime: 4690.513 ms +(9 rows) + +postgres=3D# explain select count(*) from (select distinct on (val) * =20= + +from test where val<100000000) as foo; + QUERY PLAN +------------------------------------------------------------------------=20= + +----------------- +Aggregate (cost=3D16350.20..16350.21 rows=3D1 width=3D0) + -> Unique (cost=3D0.00..13748.23 rows=3D208158 width=3D8) + -> Index Scan using testval on test (cost=3D0.00..13227.83 =20= + +rows=3D208158 width=3D8) + Index Cond: (val < 100000000) +(4 rows) + +postgres=3D# set enable_indexscan=3Doff; +postgres=3D# explain analyze select count(*) from (select distinct on =20= + +(val) * from test where val<100000000) as foo; + =20= + +QUERY PLAN +------------------------------------------------------------------------=20= + +------------------------------------------------------------------------=20= + +---- +Aggregate (cost=3D28081.27..28081.28 rows=3D1 width=3D0) (actual =20 +time=3D6444.650..6444.651 rows=3D1 loops=3D1) + -> Unique (cost=3D24438.50..25479.29 rows=3D208158 width=3D8) = +(actual =20 +time=3D5669.118..6277.206 rows=3D194142 loops=3D1) + -> Sort (cost=3D24438.50..24958.89 rows=3D208158 width=3D8) =20= + +(actual time=3D5669.112..5852.351 rows=3D194342 loops=3D1) + Sort Key: test.val + -> Bitmap Heap Scan on test (cost=3D882.55..6050.53 =20= + +rows=3D208158 width=3D8) (actual time=3D1341.114..4989.840 rows=3D194342 = +=20 +loops=3D1) + Recheck Cond: (val < 100000000) + -> Bitmap Index Scan on testval =20 +(cost=3D0.00..882.55 rows=3D208158 width=3D0) (actual =20 +time=3D1339.707..1339.707 rows=3D194342 loops=3D1) + Index Cond: (val < 100000000) +Total runtime: 6487.114 ms +(9 rows) + +postgres=3D# explain analyze select count(*) from (select distinct on =20= + +(val) * from test where val<750000000) as foo; + Q=20= + +UERY PLAN +------------------------------------------------------------------------=20= + +------------------------------------------------------------------------=20= + +------- +Aggregate (cost=3D204576.53..204576.54 rows=3D1 width=3D0) (actual =20 +time=3D35718.935..35718.936 rows=3D1 loops=3D1) + -> Unique (cost=3D178717.28..186105.64 rows=3D1477671 width=3D8) =20= + +(actual time=3D29465.856..34459.640 rows=3D1462348 loops=3D1) + -> Sort (cost=3D178717.28..182411.46 rows=3D1477671 width=3D8)= + =20 +(actual time=3D29465.853..31658.056 rows=3D1463793 loops=3D1) + Sort Key: test.val + -> Bitmap Heap Scan on test (cost=3D6256.85..27293.73 =20= + +rows=3D1477671 width=3D8) (actual time=3D8316.676..11561.018 = +rows=3D1463793 =20 +loops=3D1) + Recheck Cond: (val < 750000000) + -> Bitmap Index Scan on testval =20 +(cost=3D0.00..6256.85 rows=3D1477671 width=3D0) (actual =20 +time=3D8305.963..8305.963 rows=3D1463793 loops=3D1) + Index Cond: (val < 750000000) +Total runtime: 35736.167 ms +(9 rows) + +postgres=3D# explain analyze select count(*) from (select distinct on =20= + +(val) * from test where val<800000000) as foo; + QUERY PLAN +------------------------------------------------------------------------=20= + +------------------------------------------------------------ +Aggregate (cost=3D217582.20..217582.21 rows=3D1 width=3D0) (actual =20 +time=3D28718.331..28718.332 rows=3D1 loops=3D1) + -> Unique (cost=3D190140.72..197981.14 rows=3D1568084 width=3D8) =20= + +(actual time=3D22175.170..27380.343 rows=3D1559648 loops=3D1) + -> Sort (cost=3D190140.72..194060.93 rows=3D1568084 width=3D8)= + =20 +(actual time=3D22175.165..24451.892 rows=3D1561181 loops=3D1) + Sort Key: test.val + -> Seq Scan on test (cost=3D0.00..28780.40 =20 +rows=3D1568084 width=3D8) (actual time=3D13.130..3358.923 rows=3D1561181 = +=20 +loops=3D1) + Filter: (val < 800000000) +Total runtime: 28735.264 ms +(7 rows) + +I did not post any result for the indexscan plan, because it takes to =20= + +much time. +Why the stupid indexscan plan on the whole table ? + +Cordialement, +Jean-G=E9rard Pailloncy + + +From pgsql-performance-owner@postgresql.org Wed Nov 23 21:51:58 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 02612DAE89 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; 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Wed, 23 Nov + 2005 20:50:59 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Wed, 23 Nov 2005 17:50:57 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: stange@rentec.com +cc: "Postgresql Performance" <pgsql-performance@postgresql.org> +Message-ID: <BFAA5C81.145DB%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXweV01iY4lbERPReOGq+8vxhxRgAAICXgV +In-Reply-To: <4384E685.4060108@rentec.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 24 Nov 2005 01:50:59.0537 (UTC) + FILETIME=[849B7410:01C5F099] +X-WSS-ID: 6F9BC32419O2005981-11-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.794 required=5 tests=[AWL=0.541, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.794 +X-Spam-Level: * +X-Archive-Number: 200511/477 +X-Sequence-Number: 15734 + +Alan, + +On 11/23/05 2:00 PM, "Alan Stange" <stange@rentec.com> wrote: + +> Luke Lonergan wrote: +>> Why not contribute something - put up proof of your stated 8KB versus +>> 32KB page size improvement. +> +> I did observe that 32KB block sizes were a significant win "for our +> usage patterns". It might be a win for any of the following reasons: +> (* big snip *) + +Though all of what you relate is interesting, it seems irrelevant to your +earlier statement here: + +>> Alan Stange <stange@rentec.com> writes: +>> If your goal is sequential IO, then one must use larger block sizes. +>> No one would use 8KB IO for achieving high sequential IO rates. Simply +>> put, read() is about the slowest way to get 8KB of data. Switching +>> to 32KB blocks reduces all the system call overhead by a large margin. +>> Larger blocks would be better still, up to the stripe size of your +>> mirror. (Of course, you're using a mirror and not raid5 if you care +>> about performance.) + +And I am interested in seeing if your statement is correct. Do you have any +proof of this to share? + +- Luke + + + +From pgsql-performance-owner@postgresql.org Wed Nov 23 22:29:58 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 350F7DAE89 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 22:29:56 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 19797-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 02:29:59 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id 48D7DDA86D + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 22:29:52 -0400 (AST) +Received: from 172.16.1.112 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Wed, 23 Nov 2005 21:29:51 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Wed, 23 Nov + 2005 21:29:50 -0500 +Received: from 208.54.15.129 ([208.54.15.129]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.106]) with Microsoft Exchange Server HTTP-DAV ; Wed, 23 Nov + 2005 21:29:50 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Wed, 23 Nov 2005 18:29:49 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Mark Kirkwood" <markir@paradise.net.nz> +cc: pgsql-performance@postgresql.org, + "eng@intranet.greenplum.com" <eng@intranet.greenplum.com> +Message-ID: <BFAA659D.145E5%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXvIxdwfLDwWrP8Q669kHxJ85F1twBe9mid +In-Reply-To: <4382A840.3030401@paradise.net.nz> +MIME-Version: 1.0 +X-OriginalArrivalTime: 24 Nov 2005 02:29:50.0935 (UTC) + FILETIME=[F23A8E70:01C5F09E] +X-WSS-ID: 6F9BFA152UO2837356-01-01 +Content-Type: multipart/alternative; + boundary=B_3215615389_18058204 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=2.387 required=5 tests=[AWL=-0.103, + HTML_MESSAGE=0.001, RCVD_IN_SORBS_WEB=1.236, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 2.387 +X-Spam-Level: ** +X-Archive-Number: 200511/478 +X-Sequence-Number: 15735 + +> This message is in MIME format. Since your mail reader does not understand +this format, some or all of this message may not be legible. + +--B_3215615389_18058204 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +Mark, + +This is an excellent idea =AD unfortunately I=B9m in Maui right now (Mahalo!) +and I=B9m not getting to testing with this. My first try was with 8.0.3 and +it=B9s an 8.1 function I presume. + +Not to be lazy =AD but any hint as to how to do the same thing for 8.0? + +- Luke + + +On 11/21/05 9:10 PM, "Mark Kirkwood" <markir@paradise.net.nz> wrote: + +> Luke Lonergan wrote: +>=20 +>> > So that leaves the question - why not more than 64% of the I/O scan ra= +te? +>> > And why is it a flat 64% as the I/O subsystem increases in speed from +>> > 333-400MB/s? +>> > +>=20 +> It might be interesting to see what effect reducing the cpu consumption +> entailed by the count aggregation has - by (say) writing a little bit +> of code to heap scan the desired relation (sample attached). +>=20 +> Cheers +>=20 +> Mark +>=20 +>=20 +>=20 +>=20 +>=20 +>=20 +> /* +> * fastcount.c +> * +> * Do a count that uses considerably less CPU time than an aggregate. +> */ +>=20 +> #include "postgres.h" +>=20 +> #include "funcapi.h" +> #include "access/heapam.h" +> #include "catalog/namespace.h" +> #include "utils/builtins.h" +>=20 +>=20 +> extern Datum fastcount(PG_FUNCTION_ARGS); +>=20 +>=20 +> PG_FUNCTION_INFO_V1(fastcount); +> Datum +> fastcount(PG_FUNCTION_ARGS) +> { +> text *relname =3D PG_GETARG_TEXT_P(0); +> RangeVar *relrv; +> Relation rel; +> HeapScanDesc scan; +> HeapTuple tuple; +> int64 result =3D 0; +>=20 +> /* Use the name to get a suitable range variable and open the relation. = +*/ +> relrv =3D makeRangeVarFromNameList(textToQualifiedNameList(relname)); +> rel =3D heap_openrv(relrv, AccessShareLock); +>=20 +> /* Start a heap scan on the relation. */ +> scan =3D heap_beginscan(rel, SnapshotNow, 0, NULL); +> while ((tuple =3D heap_getnext(scan, ForwardScanDirection)) !=3D NULL) +> { +> result++; +> } +>=20 +> /* End the scan and close up the relation. */ +> heap_endscan(scan); +> heap_close(rel, AccessShareLock); +>=20 +>=20 +> PG_RETURN_INT64(result); +> } + + + +--B_3215615389_18058204 +Content-Type: text/html; + charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable + +<HTML> +<HEAD> +<TITLE>Re: [PERFORM] Hardware/OS recommendations for large databases (</TIT= +LE> +</HEAD> +<BODY> +<FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Mark,= +<BR> +<BR> +This is an excellent idea – unfortunately I’m in Maui right now= + (Mahalo!) and I’m not getting to testing with this.  My first tr= +y was with 8.0.3 and it’s an 8.1 function I presume.<BR> +<BR> +Not to be lazy – but any hint as to how to do the same thing for 8.0?= +<BR> +<BR> +- Luke<BR> +<BR> +<BR> +On 11/21/05 9:10 PM, "Mark Kirkwood" <markir@paradise.net.nz&g= +t; wrote:<BR> +<BR> +</SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= +E=3D'font-size:14.0px'>Luke Lonergan wrote:<BR> +<BR> +> So that leaves the question - why not more than 64% of the I/O scan ra= +te?<BR> +> And why is it a flat 64% as the I/O subsystem increases in speed from<= +BR> +> 333-400MB/s?<BR> +><BR> +<BR> +It might be interesting to see what effect reducing the cpu consumption<BR> +  entailed by the count aggregation has - by (say) writing a litt= +le bit<BR> +of code to heap scan the desired relation (sample attached).<BR> +<BR> +Cheers<BR> +<BR> +Mark<BR> +<BR> +<BR> +<BR> +<BR> +<BR> +<HR ALIGN=3DCENTER SIZE=3D"3" WIDTH=3D"95%"></SPAN></FONT><FONT SIZE=3D"2"><FONT FA= +CE=3D"Monaco, Courier New"><SPAN STYLE=3D'font-size:12.0px'>/*<BR> + * fastcount.c<BR> + *<BR> + * Do a count that uses considerably less CPU time than an aggregate.<= +BR> + */<BR> +<BR> +#include "postgres.h"<BR> +<BR> +#include "funcapi.h"<BR> +#include "access/heapam.h"<BR> +#include "catalog/namespace.h"<BR> +#include "utils/builtins.h"<BR> +<BR> +<BR> +extern Datum fastcount(PG_FUNCTION_ARGS);<BR> +<BR> +<BR> +PG_FUNCTION_INFO_V1(fastcount);<BR> +Datum<BR> +fastcount(PG_FUNCTION_ARGS)<BR> +{<BR> + text    *relname =3D PG_GETARG_TEXT_P(0);<BR> + RangeVar   *relrv;<BR> + Relation rel;<BR> + HeapScanDesc scan;<BR> + HeapTuple tuple;<BR> + int64  result =3D 0;<BR> +<BR> + /* Use the name to get a suitable range variable and open the relatio= +n. */<BR> + relrv =3D makeRangeVarFromNameList(textToQualifiedNameList(relname));<B= +R> + rel =3D heap_openrv(relrv, AccessShareLock);<BR> +<BR> + /* Start a heap scan on the relation. */<BR> + scan =3D heap_beginscan(rel, SnapshotNow, 0, NULL);<BR> + while ((tuple =3D heap_getnext(scan, ForwardScanDirection)) !=3D NULL)<BR= +> + {<BR> +  result++;<BR> + }<BR> +<BR> + /* End the scan and close up the relation. */<BR> + heap_endscan(scan);<BR> + heap_close(rel, AccessShareLock);<BR> +<BR> +<BR> + PG_RETURN_INT64(result);<BR> +}<BR> +</SPAN></FONT></FONT></BLOCKQUOTE><FONT SIZE=3D"2"><FONT FACE=3D"Monaco, Courie= +r New"><SPAN STYLE=3D'font-size:12.0px'><BR> +</SPAN></FONT></FONT> +</BODY> +</HTML> + + +--B_3215615389_18058204-- + + +From pgsql-performance-owner@postgresql.org Wed Nov 23 23:14:55 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 86D6ADBB09 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 23 Nov 2005 23:14:54 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 31649-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 03:14:57 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id AD883DBA4E + for <pgsql-performance@postgresql.org>; + Wed, 23 Nov 2005 23:14:51 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAO3EuwT007007; + Wed, 23 Nov 2005 22:14:56 -0500 (EST) +To: Pailloncy Jean-Gerard <jg@rilk.com> +cc: pgsql-performance@postgresql.org +Subject: Re: 8.1 count(*) distinct: IndexScan/SeqScan +In-reply-to: <334D9941-B5B3-4D18-8312-F85D0FB054ED@rilk.com> +References: <334D9941-B5B3-4D18-8312-F85D0FB054ED@rilk.com> +Comments: In-reply-to Pailloncy Jean-Gerard <jg@rilk.com> + message dated "Wed, 23 Nov 2005 23:14:47 +0100" +Date: Wed, 23 Nov 2005 22:14:56 -0500 +Message-ID: <7006.1132802096@sss.pgh.pa.us> +From: Tom Lane <tgl@sss.pgh.pa.us> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.005 required=5 tests=[AWL=0.005] +X-Spam-Score: 0.005 +X-Spam-Level: +X-Archive-Number: 200511/479 +X-Sequence-Number: 15736 + +Pailloncy Jean-Gerard <jg@rilk.com> writes: +> Why the stupid indexscan plan on the whole table ? + +Pray tell, what are you using for the planner cost parameters? +The only way I can come close to duplicating your numbers is +by setting random_page_cost to somewhere around 0.01 ... + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Thu Nov 24 02:22:00 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D4D84DB723 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 02:21:59 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 56524-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 06:21:58 +0000 (GMT) +X-Greylist: delayed 01:01:31.924714 by SQLgrey- +Received: from pillette.com (adsl-67-119-5-202.dsl.snfc21.pacbell.net + [67.119.5.202]) + by svr1.postgresql.org (Postfix) with ESMTP id 9374DDBC0C + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 02:21:56 -0400 (AST) +Received: (from andrew@localhost) + by pillette.com (8.11.6/8.11.6) id jAO5KJx03991; + Wed, 23 Nov 2005 21:20:19 -0800 +Date: Wed, 23 Nov 2005 21:20:19 -0800 +From: andrew@pillette.com +Message-Id: <200511240520.jAO5KJx03991@pillette.com> +Subject: Re: 8.1 count(*) distinct: IndexScan/SeqScan +To: Pailloncy Jean-Gerard <jg@rilk.com> +Cc: pgsql-performance@postgresql.org +X-Originating-IP: 70.137.147.241 +X-Mailer: Webmin 0.940 +MIME-Version: 1.0 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.55 required=5 tests=[NO_REAL_NAME=0.55] +X-Spam-Score: 0.55 +X-Spam-Level: +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +X-Archive-Number: 200511/481 +X-Sequence-Number: 15738 + +Pailloncy Jean-Gerard <jg@rilk.com> wrote .. +[snip] + +THIS MAY SEEM SILLY but vacuum is mispelled below and presumably there was never any ANALYZE done. + +> +> postgres=# vaccum full verbose analyze; + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 01:34:15 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 5A05BD7282 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 01:34:13 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 51167-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 05:34:12 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from linda-1.paradise.net.nz (bm-1a.paradise.net.nz + [203.96.152.180]) + by svr1.postgresql.org (Postfix) with ESMTP id 5F547D704F + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 01:34:06 -0400 (AST) +Received: from smtp-1.paradise.net.nz (tclsnelbe2-src-nat-1 [203.96.152.177]) + by linda-1.paradise.net.nz (Paradise.net.nz) + with ESMTP id <0IQG006IL24TZH@linda-1.paradise.net.nz> for + pgsql-performance@postgresql.org; Thu, 24 Nov 2005 18:34:05 +1300 (NZDT) +Received: from [192.168.1.11] (218-101-28-4.dsl.clear.net.nz [218.101.28.4]) + by smtp-1.paradise.net.nz (Postfix) with ESMTP id BEB2011536AB; Thu, + 24 Nov 2005 18:34:04 +1300 (NZDT) +Date: Thu, 24 Nov 2005 18:34:03 +1300 +From: Mark Kirkwood <markir@paradise.net.nz> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <BFAA659D.145E5%llonergan@greenplum.com> +To: Luke Lonergan <llonergan@greenplum.com> +Cc: pgsql-performance@postgresql.org, + "eng@intranet.greenplum.com" <eng@intranet.greenplum.com> +Message-id: <438550CB.5020506@paradise.net.nz> +MIME-version: 1.0 +Content-type: multipart/mixed; boundary="Boundary_(ID_QaxGn75YzNMJHffeg0xdpg)" +X-Accept-Language: en-us, en +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20051106) +References: <BFAA659D.145E5%llonergan@greenplum.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.261 required=5 tests=[AWL=0.261] +X-Spam-Score: 0.261 +X-Spam-Level: +X-Archive-Number: 200511/480 +X-Sequence-Number: 15737 + +This is a multi-part message in MIME format. + +--Boundary_(ID_QaxGn75YzNMJHffeg0xdpg) +Content-type: text/plain; charset=windows-1252; format=flowed +Content-transfer-encoding: 8BIT + +Luke Lonergan wrote: +> Mark, +> +> This is an excellent idea � unfortunately I�m in Maui right now +> (Mahalo!) and I�m not getting to testing with this. My first try was +> with 8.0.3 and it�s an 8.1 function I presume. +> +> Not to be lazy � but any hint as to how to do the same thing for 8.0? +> + +Yeah, it's 8.1 - I didn't think to check against 8.0. The attached +variant works with 8.0.4 (textToQualifiedNameList needs 2 args) + +cheers + +Mark + +P.s. Maui eh, sounds real nice. + +--Boundary_(ID_QaxGn75YzNMJHffeg0xdpg) +Content-type: text/plain; name=fastcount-8.0.c +Content-transfer-encoding: 7BIT +Content-disposition: inline; filename=fastcount-8.0.c + +/* + * fastcount.c + * + * Do a count that uses considerably less CPU time than an aggregate. + * + * (Variant for 8.0.x - textToQualifiedNameList needs 2 args) + */ + +#include "postgres.h" + +#include "funcapi.h" +#include "access/heapam.h" +#include "catalog/namespace.h" +#include "utils/builtins.h" + + +extern Datum fastcount(PG_FUNCTION_ARGS); + + +PG_FUNCTION_INFO_V1(fastcount); +Datum +fastcount(PG_FUNCTION_ARGS) +{ + text *relname = PG_GETARG_TEXT_P(0); + RangeVar *relrv; + Relation rel; + HeapScanDesc scan; + HeapTuple tuple; + int64 result = 0; + + /* Use the name to get a suitable range variable and open the relation. */ + relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname, "")); + rel = heap_openrv(relrv, AccessShareLock); + + /* Start a heap scan on the relation. */ + scan = heap_beginscan(rel, SnapshotNow, 0, NULL); + while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL) + { + result++; + } + + /* End the scan and close up the relation. */ + heap_endscan(scan); + heap_close(rel, AccessShareLock); + + + PG_RETURN_INT64(result); +} + +--Boundary_(ID_QaxGn75YzNMJHffeg0xdpg)-- + +From pgsql-performance-owner@postgresql.org Thu Nov 24 04:18:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 786B2D6EBC + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 04:18:48 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 73364-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 08:18:47 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id 2E5E3DAD64 + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 04:18:43 -0400 (AST) +Received: from 172.16.1.112 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Thu, 24 Nov 2005 03:18:38 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Thu, 24 Nov + 2005 03:17:08 -0500 +Received: from 208.54.15.129 ([208.54.15.129]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.106]) with Microsoft Exchange Server HTTP-DAV ; Thu, 24 Nov + 2005 03:17:07 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Thu, 24 Nov 2005 00:17:06 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Mark Kirkwood" <markir@paradise.net.nz> +cc: stange@rentec.com, "Greg Stark" <gsstark@mit.edu>, + "Dave Cramer" <pg@fastcrypt.com>, "Joshua Marsh" <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Message-ID: <BFAAB702.1460D%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXvIxdwfLDwWrP8Q669kHxJ85F1twBrF12i +In-Reply-To: <4382A840.3030401@paradise.net.nz> +MIME-Version: 1.0 +X-OriginalArrivalTime: 24 Nov 2005 08:17:08.0129 (UTC) + FILETIME=[762A0910:01C5F0CF] +X-WSS-ID: 6F9BA8D72UO3042572-06-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=2.396 required=5 tests=[AWL=-0.093, + RCVD_IN_SORBS_WEB=1.236, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 2.396 +X-Spam-Level: ** +X-Archive-Number: 200511/482 +X-Sequence-Number: 15739 + +Mark, + +See the results below and analysis - the pure HeapScan gets 94.1% of the max +available read bandwidth (cool!). Nothing wrong with heapscan in the +presence of large readahead, which is good news. + +That says it's something else in the path. As you probably know there is a +page lock taken, a copy of the tuple from the page, lock removed, count +incremented for every iteration of the agg node on a count(*). Is the same +true of a count(1)? + +I recall that the profile is full of memcpy and memory context calls. + +It would be nice to put some tracers into the executor and see where the +time is going. I'm also curious about the impact of the new 8.1 virtual +tuples in reducing the executor overhead. In this case my bet's on the agg +node itself, what do you think? + +- Luke + +On 11/21/05 9:10 PM, "Mark Kirkwood" <markir@paradise.net.nz> wrote: + +> Luke Lonergan wrote: +> +>> So that leaves the question - why not more than 64% of the I/O scan rate? +>> And why is it a flat 64% as the I/O subsystem increases in speed from +>> 333-400MB/s? +>> +> +> It might be interesting to see what effect reducing the cpu consumption +> entailed by the count aggregation has - by (say) writing a little bit +> of code to heap scan the desired relation (sample attached). + +OK - here are results for a slightly smaller (still bigger than RAM) +lineitem on the same machine, using the same xfs filesystem that achieved +407MB/s: + +============================================================================ +12.9GB of DBT-3 data from the lineitem table +============================================================================ +llonergan=# select relpages from pg_class where relname='lineitem'; + relpages +---------- + 1579270 +(1 row) + +1579270*8192/1000000 +12937 Million Bytes or 12.9GB + +llonergan=# \timing +Timing is on. +llonergan=# select count(1) from lineitem; + count +---------- + 59986052 +(1 row) + +Time: 197870.105 ms +llonergan=# select count(1) from lineitem; + count +---------- + 59986052 +(1 row) + +Time: 49912.164 ms +llonergan=# select count(1) from lineitem; + count +---------- + 59986052 +(1 row) + +Time: 49218.739 ms + +llonergan=# select fastcount('lineitem'); + fastcount +----------- + 59986052 +(1 row) + +Time: 33752.778 ms +llonergan=# select fastcount('lineitem'); + fastcount +----------- + 59986052 +(1 row) + +Time: 34543.646 ms +llonergan=# select fastcount('lineitem'); + fastcount +----------- + 59986052 +(1 row) + +Time: 34528.053 ms + +============================================================================ +Analysis: +============================================================================ + Bandwidth Percent of max +dd Read 407MB/s 100% +Count(1) 263MB/s 64.6% +HeapScan 383MB/s 94.1% + +Wow - looks like the HeapScan gets almost all of the available bandwidth! + +- Luke + + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 04:53:20 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CFDB9D7E05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 04:53:19 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 77617-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 08:53:20 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from linda-1.paradise.net.nz (bm-1a.paradise.net.nz + [203.96.152.180]) + by svr1.postgresql.org (Postfix) with ESMTP id 1FB9DD6EBC + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 04:53:17 -0400 (AST) +Received: from smtp-3.paradise.net.nz (tclsnelbe2-src-nat-1 [203.96.152.177]) + by linda-1.paradise.net.nz (Paradise.net.nz) + with ESMTP id <0IQG00D0SBCUTY@linda-1.paradise.net.nz> for + pgsql-performance@postgresql.org; Thu, 24 Nov 2005 21:53:18 +1300 (NZDT) +Received: from [192.168.1.11] (218-101-28-4.dsl.clear.net.nz [218.101.28.4]) + by smtp-3.paradise.net.nz (Postfix) with ESMTP id E8612F24F3F; Thu, + 24 Nov 2005 21:53:17 +1300 (NZDT) +Date: Thu, 24 Nov 2005 21:53:16 +1300 +From: Mark Kirkwood <markir@paradise.net.nz> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <BFAAB702.1460D%llonergan@greenplum.com> +To: Luke Lonergan <llonergan@greenplum.com> +Cc: stange@rentec.com, Greg Stark <gsstark@mit.edu>, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Message-id: <43857F7C.6060305@paradise.net.nz> +MIME-version: 1.0 +Content-type: text/plain; format=flowed; charset=ISO-8859-1 +Content-transfer-encoding: 7bit +X-Accept-Language: en-us, en +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20051106) +References: <BFAAB702.1460D%llonergan@greenplum.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.24 required=5 tests=[AWL=0.240] +X-Spam-Score: 0.24 +X-Spam-Level: +X-Archive-Number: 200511/483 +X-Sequence-Number: 15740 + +Luke Lonergan wrote: + +> ============================================================================ +> 12.9GB of DBT-3 data from the lineitem table +> ============================================================================ +> llonergan=# select relpages from pg_class where relname='lineitem'; +> relpages +> ---------- +> 1579270 +> (1 row) +> +> 1579270*8192/1000000 +> 12937 Million Bytes or 12.9GB +> +> llonergan=# \timing +> Timing is on. +> llonergan=# select count(1) from lineitem; +> count +> ---------- +> 59986052 +> (1 row) +> +> Time: 197870.105 ms + +So 198 seconds is the uncached read time with count (Just for clarity, +did you clear the Pg and filesystem caches or unmount / remount the +filesystem?) + +> llonergan=# select count(1) from lineitem; +> count +> ---------- +> 59986052 +> (1 row) +> +> Time: 49912.164 ms +> llonergan=# select count(1) from lineitem; +> count +> ---------- +> 59986052 +> (1 row) +> +> Time: 49218.739 ms +> + +and ~50 seconds is the (partially) cached read time with count + +> llonergan=# select fastcount('lineitem'); +> fastcount +> ----------- +> 59986052 +> (1 row) +> +> Time: 33752.778 ms +> llonergan=# select fastcount('lineitem'); +> fastcount +> ----------- +> 59986052 +> (1 row) +> +> Time: 34543.646 ms +> llonergan=# select fastcount('lineitem'); +> fastcount +> ----------- +> 59986052 +> (1 row) +> +> Time: 34528.053 ms +> + +so ~34 seconds is the (partially) cached read time for fastcount - +I calculate this to give ~362Mb/s effective IO rate (I'm doing / by +1024*1024 not 1000*1000) FWIW. + +While this is interesting, you probably want to stop Pg, unmount the +filesystem, and restart Pg to get the uncached time for fastcount too +(and how does this compare to uncached read with dd using the same block +size?). + +But at this stage it certainly looks the the heapscan code is pretty +efficient - great! + +Oh - and do you want to try out 32K block size, I'm interested to see +what level of improvement you get (as my system is hopelessly cpu bound...)! + +> ============================================================================ +> Analysis: +> ============================================================================ +> Bandwidth Percent of max +> dd Read 407MB/s 100% +> Count(1) 263MB/s 64.6% +> HeapScan 383MB/s 94.1% + + +Cheers + +Mark + +From pgsql-performance-owner@postgresql.org Thu Nov 24 05:11:42 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 447DDDAF8D + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 05:11:41 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 79720-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 09:11:42 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from linda-1.paradise.net.nz (bm-1a.paradise.net.nz + [203.96.152.180]) + by svr1.postgresql.org (Postfix) with ESMTP id C419ED6EBC + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 05:11:38 -0400 (AST) +Received: from smtp-2.paradise.net.nz (tclsnelbe2-src-nat-1 [203.96.152.177]) + by linda-1.paradise.net.nz (Paradise.net.nz) + with ESMTP id <0IQG00E8WC7GS3@linda-1.paradise.net.nz> for + pgsql-performance@postgresql.org; Thu, 24 Nov 2005 22:11:40 +1300 (NZDT) +Received: from [192.168.1.11] (218-101-28-4.dsl.clear.net.nz [218.101.28.4]) + by smtp-2.paradise.net.nz (Postfix) with ESMTP id 83A9D9AE7B0; Thu, + 24 Nov 2005 22:11:38 +1300 (NZDT) +Date: Thu, 24 Nov 2005 22:11:36 +1300 +From: Mark Kirkwood <markir@paradise.net.nz> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <BFAAB702.1460D%llonergan@greenplum.com> +To: Luke Lonergan <llonergan@greenplum.com> +Cc: stange@rentec.com, Greg Stark <gsstark@mit.edu>, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Message-id: <438583C8.4050809@paradise.net.nz> +MIME-version: 1.0 +Content-type: text/plain; format=flowed; charset=ISO-8859-1 +Content-transfer-encoding: 7bit +X-Accept-Language: en-us, en +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20051106) +References: <BFAAB702.1460D%llonergan@greenplum.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.222 required=5 tests=[AWL=0.222] +X-Spam-Score: 0.222 +X-Spam-Level: +X-Archive-Number: 200511/484 +X-Sequence-Number: 15741 + +Luke Lonergan wrote: +> Mark, +> +> +> It would be nice to put some tracers into the executor and see where the +> time is going. I'm also curious about the impact of the new 8.1 virtual +> tuples in reducing the executor overhead. In this case my bet's on the agg +> node itself, what do you think? +> + +Yeah - it's pretty clear that the count aggregate is fairly expensive +wrt cpu - However, I am not sure if all agg nodes suffer this way (guess +we could try a trivial aggregate that does nothing for all tuples bar +the last and just reports the final value it sees). + +Cheers + +Mark + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 05:23:05 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id C4527DBA6C + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 05:23:04 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 80935-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 09:23:05 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw01.mi8.com [63.240.6.47]) + by svr1.postgresql.org (Postfix) with ESMTP id BC261DBA04 + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 05:23:01 -0400 (AST) +Received: from 172.16.1.112 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D1)); Thu, 24 Nov 2005 04:22:52 -0500 +X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Thu, 24 Nov + 2005 04:22:04 -0500 +Received: from 208.54.15.129 ([208.54.15.129]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.106]) with Microsoft Exchange Server HTTP-DAV ; Thu, 24 Nov + 2005 04:22:03 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Thu, 24 Nov 2005 01:22:03 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Mark Kirkwood" <markir@paradise.net.nz> +cc: stange@rentec.com, "Greg Stark" <gsstark@mit.edu>, + "Dave Cramer" <pg@fastcrypt.com>, "Joshua Marsh" <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Message-ID: <BFAAC63B.14618%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXw1IoT6owKGP/7ThSbYUo+hMe9tAAA/2fi +In-Reply-To: <43857F7C.6060305@paradise.net.nz> +MIME-Version: 1.0 +X-OriginalArrivalTime: 24 Nov 2005 09:22:04.0773 (UTC) + FILETIME=[88BEB950:01C5F0D8] +X-WSS-ID: 6F9B59ED3282408891-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.787 required=5 tests=[AWL=0.534, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.787 +X-Spam-Level: * +X-Archive-Number: 200511/485 +X-Sequence-Number: 15742 + +Mark, + +>> Time: 197870.105 ms +> +> So 198 seconds is the uncached read time with count (Just for clarity, +> did you clear the Pg and filesystem caches or unmount / remount the +> filesystem?) + +Nope - the longer time is due to the "second write" known issue with +Postgres - it writes the data to the table, but all of the pages are marked +dirty? So, always on the first scan after loading they are written again. +This is clear as you watch vmstat - the pattern on the first seq scan is +half read / half write. + +>> Time: 49218.739 ms +>> +> +> and ~50 seconds is the (partially) cached read time with count + +Again - the pattern here is pure read and completely non-cached. You see a +very nearly constant I/O rate when watching vmstat for the entire scan. + +>> Time: 34528.053 ms + +> so ~34 seconds is the (partially) cached read time for fastcount - +> I calculate this to give ~362Mb/s effective IO rate (I'm doing / by +> 1024*1024 not 1000*1000) FWIW. + +The dd number uses 1000*1000, so I maintained it for the percentage of max. + +> While this is interesting, you probably want to stop Pg, unmount the +> filesystem, and restart Pg to get the uncached time for fastcount too +> (and how does this compare to uncached read with dd using the same block +> size?). + +I'll do it again sometime, but I've already deleted the file. I've done the +following in the past to validate this though: + +- Reboot machine +- Rerun scan + +And we get identical results. + +> But at this stage it certainly looks the the heapscan code is pretty +> efficient - great! + +Yep. + +> Oh - and do you want to try out 32K block size, I'm interested to see +> what level of improvement you get (as my system is hopelessly cpu bound...)! + +Yah - done so in the past and not seen any - was waiting for Alan to post +his results. + +>> ============================================================================ +>> Analysis: +>> ============================================================================ +>> Bandwidth Percent of max +>> dd Read 407MB/s 100% +>> Count(1) 263MB/s 64.6% +>> HeapScan 383MB/s 94.1% + +Note these are all in consistent 1000x1000 units. + +Thanks for the test - neat trick! We'll use it to do some more profiling +some time soon... + +- Luke + + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 05:24:39 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 76A77DAD64 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 05:24:38 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 80244-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 09:24:39 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from linda-1.paradise.net.nz (bm-1a.paradise.net.nz + [203.96.152.180]) + by svr1.postgresql.org (Postfix) with ESMTP id DBB74D6EBC + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 05:24:35 -0400 (AST) +Received: from smtp-3.paradise.net.nz (tclsnelbe2-src-nat-1 [203.96.152.177]) + by linda-1.paradise.net.nz (Paradise.net.nz) + with ESMTP id <0IQG00FYKCT1WO@linda-1.paradise.net.nz> for + pgsql-performance@postgresql.org; Thu, 24 Nov 2005 22:24:37 +1300 (NZDT) +Received: from [192.168.1.11] (218-101-28-4.dsl.clear.net.nz [218.101.28.4]) + by smtp-3.paradise.net.nz (Postfix) with ESMTP id 2B27E139AD8A; Thu, + 24 Nov 2005 22:24:37 +1300 (NZDT) +Date: Thu, 24 Nov 2005 22:24:35 +1300 +From: Mark Kirkwood <markir@paradise.net.nz> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <BFAAB702.1460D%llonergan@greenplum.com> +To: Luke Lonergan <llonergan@greenplum.com> +Cc: stange@rentec.com, Greg Stark <gsstark@mit.edu>, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Message-id: <438586D3.9010701@paradise.net.nz> +MIME-version: 1.0 +Content-type: text/plain; format=flowed; charset=ISO-8859-1 +Content-transfer-encoding: 7bit +X-Accept-Language: en-us, en +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20051106) +References: <BFAAB702.1460D%llonergan@greenplum.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.207 required=5 tests=[AWL=0.207] +X-Spam-Score: 0.207 +X-Spam-Level: +X-Archive-Number: 200511/486 +X-Sequence-Number: 15743 + +Luke Lonergan wrote: + +> That says it's something else in the path. As you probably know there is a +> page lock taken, a copy of the tuple from the page, lock removed, count +> incremented for every iteration of the agg node on a count(*). Is the same +> true of a count(1)? +> + +Sorry Luke - message 3 - I seem to be suffering from a very small +working memory buffer myself right now, I think it's after a day of +working with DB2 ... :-) + +Anyway, as I read src/backend/parser/gram.y:6542 - count(*) is +transformed into count(1), so these two are identical. + +Cheers (last time tonight, promise!) + +Mark + +From pgsql-performance-owner@postgresql.org Thu Nov 24 05:26:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 616F5DBA6C + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 05:26:48 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 81013-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 09:26:49 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from linda-1.paradise.net.nz (bm-1a.paradise.net.nz + [203.96.152.180]) + by svr1.postgresql.org (Postfix) with ESMTP id BEBBDDBA04 + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 05:26:45 -0400 (AST) +Received: from smtp-1.paradise.net.nz (tclsnelbe2-src-nat-1 [203.96.152.177]) + by linda-1.paradise.net.nz (Paradise.net.nz) + with ESMTP id <0IQG00FLYCWNWO@linda-1.paradise.net.nz> for + pgsql-performance@postgresql.org; Thu, 24 Nov 2005 22:26:47 +1300 (NZDT) +Received: from [192.168.1.11] (218-101-28-4.dsl.clear.net.nz [218.101.28.4]) + by smtp-1.paradise.net.nz (Postfix) with ESMTP id B7661BB9147; Thu, + 24 Nov 2005 22:26:46 +1300 (NZDT) +Date: Thu, 24 Nov 2005 22:26:44 +1300 +From: Mark Kirkwood <markir@paradise.net.nz> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <BFAAC63B.14618%llonergan@greenplum.com> +To: Luke Lonergan <llonergan@greenplum.com> +Cc: stange@rentec.com, Greg Stark <gsstark@mit.edu>, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Message-id: <43858754.4020300@paradise.net.nz> +MIME-version: 1.0 +Content-type: text/plain; format=flowed; charset=ISO-8859-1 +Content-transfer-encoding: 7bit +X-Accept-Language: en-us, en +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20051106) +References: <BFAAC63B.14618%llonergan@greenplum.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.193 required=5 tests=[AWL=0.193] +X-Spam-Score: 0.193 +X-Spam-Level: +X-Archive-Number: 200511/487 +X-Sequence-Number: 15744 + +Luke Lonergan wrote: +> Mark, +> +> +>>>Time: 197870.105 ms +>> +>>So 198 seconds is the uncached read time with count (Just for clarity, +>>did you clear the Pg and filesystem caches or unmount / remount the +>>filesystem?) +> +> +> Nope - the longer time is due to the "second write" known issue with +> Postgres - it writes the data to the table, but all of the pages are marked +> dirty? So, always on the first scan after loading they are written again. +> This is clear as you watch vmstat - the pattern on the first seq scan is +> half read / half write. +> + +Ah - indeed - first access after a COPY no? I should have thought of +that, sorry! + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 09:53:55 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 2E211D721E + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 09:53:54 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 16626-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 13:53:56 +0000 (GMT) +X-Greylist: delayed 03:14:54.681692 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 0E567DBBD6 + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 09:53:50 -0400 (AST) +Received: from mail.aeccom.com (port-83-236-156-26.static.qsc.de + [83.236.156.26]) + by svr2.postgresql.org (Postfix) with ESMTP id 58A51F0B10 + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 10:38:56 +0000 (GMT) +Received: from localhost (localhost.localdomain [127.0.0.1]) + by mail.aeccom.com (Postfix) with ESMTP id 66A481CB48; + Thu, 24 Nov 2005 11:38:48 +0100 (CET) +Received: from mail.aeccom.com ([127.0.0.1]) + by localhost (gate6.aeccom.com [127.0.0.1]) (amavisd-new, port 10024) + with LMTP id 25878-01-22; Thu, 24 Nov 2005 11:38:47 +0100 (CET) +Received: from [192.168.2.14] (andes.core.aeccom.com [192.168.2.14]) + by mail.aeccom.com (Postfix) with ESMTP id 3D71C1CB53; + Thu, 24 Nov 2005 11:38:47 +0100 (CET) +Message-ID: <43859837.8040101@aeccom.com> +Date: Thu, 24 Nov 2005 11:38:47 +0100 +From: Sven Geisler <sgeisler@aeccom.com> +Organization: AEC/communications GmbH +User-Agent: Mozilla Thunderbird 1.0.6 (Windows/20050716) +X-Accept-Language: de-DE, de, en-us, en +MIME-Version: 1.0 +To: Anjan Dave <adave@vantage.com> +Cc: Scott Marlowe <smarlowe@g2switchworks.com>, + Tom Lane <tgl@sss.pgh.pa.us>, Vivek Khera <vivek@khera.org>, + Postgresql Performance <pgsql-performance@postgresql.org> +Subject: Re: High context switches occurring +References: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098E78@vt-pe2550-001.vantage.vantage.com> +In-Reply-To: + <4BAFBB6B9CC46F41B2AD7D9F4BBAF785098E78@vt-pe2550-001.vantage.vantage.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: amavisd-new at aeccom.com +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/493 +X-Sequence-Number: 15750 + +Hi Anjan, + +I can support Scott. You should turn on HT if you see high values for CS. + +I do have a few customers running a web-based 3-tier application with +PostgreSQL. We had to turn off HT to have better overall performance. +The issue is the behavior under high load. I notice that HT on does +collapse faster. + +Just a question. Which version of XEON do you have? What is does the +server have as memory architecture. + +I think, Dual-Core XEON's are no issue. One of our customers does use a +4-way Dual-Core Opteron 875 since a few months. We have Pg 8.0.3 and it +runs perfect. I have to say that we use a special patch from Tom which +fix an issue with the looking of shared buffers and the Opteron. +I notice that this patch is also useful for XEON's with EMT64. + +Best regards +Sven. + +Anjan Dave schrieb: +> Yes, it's turned on, unfortunately it got overlooked during the setup, +> and until now...! +> +> It's mostly a 'read' application, I increased the vm.max-readahead to +> 2048 from the default 256, after which I've not seen the CS storm, +> though it could be incidental. +> +> Thanks, +> Anjan +> +> -----Original Message----- +> From: Scott Marlowe [mailto:smarlowe@g2switchworks.com] +> Sent: Tuesday, November 22, 2005 3:38 PM +> To: Anjan Dave +> Cc: Tom Lane; Vivek Khera; Postgresql Performance +> Subject: Re: [PERFORM] High context switches occurring +> +> On Tue, 2005-11-22 at 14:33, Anjan Dave wrote: +> +>>Is there any way to get a temporary relief from this Context Switching +>>storm? Does restarting postmaster help? +>> +>>It seems that I can recreate the heavy CS with just one SELECT +>>statement...and then when multiple such SELECT queries are coming in, +>>things just get hosed up until we cancel a bunch of queries... +> +> +> Is your machine a hyperthreaded one? Some folks have found that turning +> off hyper threading helps. I knew it made my servers better behaved in +> the past. +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 2: Don't 'kill -9' the postmaster + +-- +/This email and any files transmitted with it are confidential and +intended solely for the use of the individual or entity to whom they +are addressed. If you are not the intended recipient, you should not +copy it, re-transmit it, use it or disclose its contents, but should +return it to the sender immediately and delete your copy from your +system. Thank you for your cooperation./ + +Sven Geisler <sgeisler@aeccom.com> Tel +49.30.5362.1627 Fax .1638 +Senior Developer, AEC/communications GmbH Berlin, Germany + +From pgsql-performance-owner@postgresql.org Thu Nov 24 07:54:37 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 9AC56DBBA1 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 07:54:36 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 00387-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 11:54:38 +0000 (GMT) +X-Greylist: delayed 13:39:23.443934 by SQLgrey- +Received: from mail.rilk.com (mail.rilk.com [193.19.217.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 6C049DBB98 + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 07:54:32 -0400 (AST) +Received: from [192.168.0.1] (cev75-1-81-57-249-136.fbx.proxad.net + [81.57.249.136]) (authenticated bits=0) + by mail.rilk.com (8.13.0/8.13.0) with ESMTP id jAOBsQgS008207 + (version=TLSv1/SSLv3 cipher=EDH-DSS-DES-CBC3-SHA bits=168 verify=NO); + Thu, 24 Nov 2005 12:54:32 +0100 (CET) +In-Reply-To: <200511240520.jAO5KJx03991@pillette.com> +References: <200511240520.jAO5KJx03991@pillette.com> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: text/plain; charset=ISO-8859-1; delsp=yes; format=flowed +Message-Id: <D629E6A4-81A4-42F0-9702-68883971F05E@rilk.com> +Cc: andrew@pillette.com +Content-Transfer-Encoding: quoted-printable +From: Pailloncy Jean-Gerard <jg@rilk.com> +Subject: Re: 8.1 count(*) distinct: IndexScan/SeqScan +Date: Thu, 24 Nov 2005 12:54:25 +0100 +To: pgsql-performance@postgresql.org +X-Mailer: Apple Mail (2.746.2) +X-DCC-CTc-dcc2-Metrics: mail.rilk.com 1031; Body=3 Fuz1=3 Fuz2=3 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/488 +X-Sequence-Number: 15745 + +> THIS MAY SEEM SILLY but vacuum is mispelled below and presumably =20 +> there was never any ANALYZE done. +> +>> +>> postgres=3D# vaccum full verbose analyze; +I do have done the "vacUUm full verbose analyze;". +But I copy/paste the wrong line. + +Cordialement, +Jean-G=E9rard Pailloncy + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 07:54:53 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id DF914DBAB1 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 07:54:51 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 01575-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 11:54:53 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.rilk.com (mail.rilk.com [193.19.217.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 88EF3DB939 + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 07:54:48 -0400 (AST) +Received: from [192.168.0.1] (cev75-1-81-57-249-136.fbx.proxad.net + [81.57.249.136]) (authenticated bits=0) + by mail.rilk.com (8.13.0/8.13.0) with ESMTP id jAOBsQgT008207 + (version=TLSv1/SSLv3 cipher=EDH-DSS-DES-CBC3-SHA bits=168 verify=NO); + Thu, 24 Nov 2005 12:54:51 +0100 (CET) +In-Reply-To: <7006.1132802096@sss.pgh.pa.us> +References: <334D9941-B5B3-4D18-8312-F85D0FB054ED@rilk.com> + <7006.1132802096@sss.pgh.pa.us> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: text/plain; charset=ISO-8859-1; delsp=yes; format=flowed +Message-Id: <7F8AA93A-431E-44E9-9339-F4BDA5FD7760@rilk.com> +Cc: Tom Lane <tgl@sss.pgh.pa.us> +Content-Transfer-Encoding: quoted-printable +From: Pailloncy Jean-Gerard <jg@rilk.com> +Subject: Re: 8.1 count(*) distinct: IndexScan/SeqScan +Date: Thu, 24 Nov 2005 12:54:50 +0100 +To: pgsql-performance@postgresql.org +X-Mailer: Apple Mail (2.746.2) +X-DCC-CTc-dcc2-Metrics: mail.rilk.com 1031; Body=2 Fuz1=2 Fuz2=2 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/489 +X-Sequence-Number: 15746 + +> Pailloncy Jean-Gerard <jg@rilk.com> writes: +>> Why the stupid indexscan plan on the whole table ? +> +> Pray tell, what are you using for the planner cost parameters? +> The only way I can come close to duplicating your numbers is +> by setting random_page_cost to somewhere around 0.01 ... +> + +I did not change the costs. + + > grep cost postgresql.conf +# note: increasing max_connections costs ~400 bytes of shared memory per +# note: increasing max_prepared_transactions costs ~600 bytes of =20 +shared memory +#vacuum_cost_delay =3D 0 # 0-1000 milliseconds +#vacuum_cost_page_hit =3D 1 # 0-10000 credits +#vacuum_cost_page_miss =3D 10 # 0-10000 credits +#vacuum_cost_page_dirty =3D 20 # 0-10000 credits +#vacuum_cost_limit =3D 200 # 0-10000 credits +#random_page_cost =3D 4 # units are one sequential =20 +page fetch + # cost +#cpu_tuple_cost =3D 0.01 # (same) +#cpu_index_tuple_cost =3D 0.001 # (same) +#cpu_operator_cost =3D 0.0025 # (same) +#autovacuum_vacuum_cost_delay =3D -1 # default vacuum cost delay = +for + # vacuum_cost_delay +#autovacuum_vacuum_cost_limit =3D -1 # default vacuum cost limit = +for + # vacuum_cost_limit + + +Cordialement, +Jean-G=E9rard Pailloncy + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 08:41:25 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 478F7D8323 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 08:41:24 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 05111-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 12:41:26 +0000 (GMT) +X-Greylist: delayed 00:15:07.660252 by SQLgrey- +Received: from travis.trilogy.com (unknown [149.75.65.93]) + by svr1.postgresql.org (Postfix) with ESMTP id A3C63D721E + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 08:41:21 -0400 (AST) +To: pgsql-performance@postgresql.org +Subject: xlog flush request error +MIME-Version: 1.0 +X-Mailer: Lotus Notes Release 5.0.9 November 16, 2001 +Message-ID: <OF52A26328.BA64DC8C-ON862570C3.00440956@trilogy.com> +From: Vipul.Gupta@trilogy.com +Date: Thu, 24 Nov 2005 06:24:32 -0600 +X-MIMETrack: Serialize by Router on Travis/Trilogy(Release 5.0.12 |February + 13, + 2003) at 11/24/2005 06:39:44 AM, + Serialize complete at 11/24/2005 06:39:44 AM +Content-Type: multipart/alternative; + boundary="=_alternative 00443E43652570C3_=" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.551 required=5 tests=[HTML_MESSAGE=0.001, + NO_REAL_NAME=0.55] +X-Spam-Score: 0.551 +X-Spam-Level: +X-Archive-Number: 200511/490 +X-Sequence-Number: 15747 + +This is a multipart message in MIME format. +--=_alternative 00443E43652570C3_= +Content-Type: text/plain; charset="us-ascii" + +Hi , + +i get the following error on doing anything with the database after +starting it. +Can anyone suggest how do i fix this + + xlog flush request 7/7D02338C is not satisfied --- flushed only to +3/2471E324 + +Vipul Gupta + +--=_alternative 00443E43652570C3_= +Content-Type: text/html; charset="us-ascii" + + +<br><font size=2 face="sans-serif">Hi ,</font> +<br> +<br><font size=2 face="sans-serif">i get the following error on doing anything with the database after starting it.</font> +<br><font size=2 face="sans-serif">Can anyone suggest how do i fix this</font> +<br> +<br><font size=2 face="sans-serif"> xlog flush request 7/7D02338C is not satisfied --- flushed only to 3/2471E324</font> +<br> +<br><font size=2 face="sans-serif">Vipul Gupta<br> +</font> +--=_alternative 00443E43652570C3_=-- + +From pgsql-performance-owner@postgresql.org Thu Nov 24 09:06:57 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 83DE9DB9C0 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; 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+ Thu, 24 Nov 2005 13:06:48 GMT +X-Originating-IP: [84.210.10.106] +X-Originating-Email: [bealach_na_bo@hotmail.com] +X-Sender: bealach_na_bo@hotmail.com +From: "Bealach-na Bo" <bealach_na_bo@hotmail.com> +To: pgsql-performance@postgresql.org +Subject: Very slow queries - please help. +Date: Thu, 24 Nov 2005 13:06:48 +0000 +Mime-Version: 1.0 +Content-Type: text/plain; format=flowed +X-OriginalArrivalTime: 24 Nov 2005 13:06:49.0106 (UTC) + FILETIME=[EE08A720:01C5F0F7] +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.919 required=5 tests=[DNS_FROM_RFC_ABUSE=0.479, + DNS_FROM_RFC_POST=1.44, MSGID_FROM_MTA_HEADER=0] +X-Spam-Score: 1.919 +X-Spam-Level: * +X-Archive-Number: 200511/491 +X-Sequence-Number: 15748 + +Hi Folks, + +I'm new to Postgresql. + +I'm having great difficulties getting the performance I had hoped for +from Postgresql 8.0. The typical query below takes ~20 minutes !! + +I hope an expert out there will tell me what I'm doing wrong - I hope +*I* am doing something wrong. + +Hardware +-------- +Single processor, Intel Xeon 3.06 GHz machine running Red Hat +Ent. 4. with 1.5 GB of RAM. + +The machine is dedicated to running Postgresql 8.0 and Apache/mod_perl +etc. The database is being accessed for report generation via a web +form. The web server talks to Pg over TCP/IP (I know, that I don't +need to do this if they are all on the same machine, but I have good +reasons for this and don't suspect that this is where my problems are +- I have the same poor performance when running from psql on the +server.) + +Database +-------- +Very simple, not fully normalized set of two tables. The first table, +very small (2000 lines of 4 cols with very few chars and integers in +in col). The other quite a bit larger (500000 lines with 15 +cols. with the largest fields ~ 256 chars) + +Typical query +------------ + +SELECT n.name +FROM node n +WHERE n.name +LIKE '56x%' +AND n.type='H' +AND n.usage='TEST' +AND n.node_id +NOT IN +(select n.node_id +FROM job_log j +INNER JOIN node n +ON j.node_id = n.node_id +WHERE n.name +LIKE '56x%' +AND n.type='H' +AND n.usage='TEST' +AND j.job_name = 'COPY FILES' +AND j.job_start >= '2005-11-14 00:00:00' +AND (j.job_stop <= '2005-11-22 09:31:10' OR j.job_stop IS NULL)) +ORDER BY n.name + + +The node table is the small table and the job_log table is the large +table. + + +I've tried all the basic things that I found in the documentation like +VACUUM ANALYZE, EXPLAIN etc., but I suspect there is something +terribly wrong with what I'm doing and these measures will not shave +off 19 min and 50 seconds off the query time. + +Any help and comments would be very much appreciated. + + +Bealach + + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 09:23:39 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6CD36DBCA8 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 09:23:38 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 12793-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 13:23:40 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.205]) + by svr1.postgresql.org (Postfix) with ESMTP id F1BA3DBC88 + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 09:23:34 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id 69so1668232wri + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 05:23:38 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=VlN3lxkmGQjDnrTMGsperlYDrYQPTErg/6ISfyRhV8AFz0kTL04MWbk5son4gqbw8F/NrrN7Q3VdSzjH+q7UL0kEScgxMeUaWKYANgWvkCwqM01IP5wNn5pUHzEQipo7JOQq03Em9Xpk9JfVNTlPthgzV85Ux6ObmvsubYnzMMU= +Received: by 10.65.234.16 with SMTP id l16mr7140663qbr; + Thu, 24 Nov 2005 05:23:38 -0800 (PST) +Received: by 10.65.192.16 with HTTP; Thu, 24 Nov 2005 05:23:38 -0800 (PST) +Message-ID: <b41c75520511240523t3372661fw@mail.gmail.com> +Date: Thu, 24 Nov 2005 14:23:38 +0100 +From: Claus Guttesen <kometen@gmail.com> +To: Bealach-na Bo <bealach_na_bo@hotmail.com> +Subject: Re: Very slow queries - please help. +Cc: pgsql-performance@postgresql.org +In-Reply-To: <BAY101-F89F00F81CBAF5B66A6EE0AD540@phx.gbl> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <BAY101-F89F00F81CBAF5B66A6EE0AD540@phx.gbl> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[UPPERCASE_25_50=0] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/492 +X-Sequence-Number: 15749 + +> Typical query +> ------------ +> +> SELECT n.name +> FROM node n +> WHERE n.name +> LIKE '56x%' +> AND n.type=3D'H' +> AND n.usage=3D'TEST' +> AND n.node_id +> NOT IN +> (select n.node_id +> FROM job_log j +> INNER JOIN node n +> ON j.node_id =3D n.node_id +> WHERE n.name +> LIKE '56x%' +> AND n.type=3D'H' +> AND n.usage=3D'TEST' +> AND j.job_name =3D 'COPY FILES' +> AND j.job_start >=3D '2005-11-14 00:00:00' +> AND (j.job_stop <=3D '2005-11-22 09:31:10' OR j.job_stop IS NULL)) +> ORDER BY n.name + +Do you have any indexes? + +regards +Claus + +From pgsql-performance-owner@postgresql.org Thu Nov 24 10:36:08 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id CA957DBC0C + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 10:36:06 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 45293-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 14:36:09 +0000 (GMT) +X-Greylist: delayed 01:29:13.338951 by SQLgrey- +Received: from hotmail.com (bay101-f39.bay101.hotmail.com [64.4.56.49]) + by svr1.postgresql.org (Postfix) with ESMTP id A520BDBC7A + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 10:36:02 -0400 (AST) +Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; + Thu, 24 Nov 2005 06:36:06 -0800 +Message-ID: <BAY101-F398BCDC77A2C41D225B978AD540@phx.gbl> +Received: from 64.4.56.200 by by101fd.bay101.hotmail.msn.com with HTTP; + Thu, 24 Nov 2005 14:36:06 GMT +X-Originating-IP: [84.210.10.106] +X-Originating-Email: [bealach_na_bo@hotmail.com] +X-Sender: bealach_na_bo@hotmail.com +In-Reply-To: <b41c75520511240523t3372661fw@mail.gmail.com> +From: "Bealach-na Bo" <bealach_na_bo@hotmail.com> +To: kometen@gmail.com +Cc: pgsql-performance@postgresql.org +Subject: Re: Very slow queries - please help. +Date: Thu, 24 Nov 2005 14:36:06 +0000 +Mime-Version: 1.0 +Content-Type: text/plain; format=flowed +X-OriginalArrivalTime: 24 Nov 2005 14:36:06.0791 (UTC) + FILETIME=[67768170:01C5F104] +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.439 required=5 tests=[AWL=-0.480, + DNS_FROM_RFC_ABUSE=0.479, DNS_FROM_RFC_POST=1.44, + MSGID_FROM_MTA_HEADER=0] +X-Spam-Score: 1.439 +X-Spam-Level: * +X-Archive-Number: 200511/494 +X-Sequence-Number: 15751 + + +Hi, + +Thanks for your comments. I've explicitly made any indexes, but the +default ones are: + + + +user@10.0.0.2.dbdev=> \di + List of relations +Schema | Name | Type | Owner | Table +---------+-----------------+-------+---------+--------- +user | job_log_id_pkey | index | user | job_log +user | node_id_pkey | index | user | node +user | node_name_key | index | user | node +(3 rows) + + + +I'm also sending the EXPLAIN outputs. + + + + + + explain SELECT n.name,n.type, + n.usage, j.status, + j.job_start,j.job_stop, + j.nfiles_in_job,j.job_name + FROM job_log j + INNER JOIN node n + ON j.node_id = n.node_id + WHERE n.name + LIKE '56x%' + AND n.type = 'K' + AND n.usage = 'LIVE' + AND j.job_name = 'COPY FILES' + AND j.job_start >= '2005-11-14 00:00:00' + AND (j.job_stop <= '2005-11-14 05:00:00' OR j.job_stop IS NULL) + ORDER BY n.name; + + + + QUERY PLAN +-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- +Nested Loop (cost=0.00..75753.31 rows=1 width=461) + Join Filter: ("inner".node_id = "outer".node_id) + -> Index Scan using node_name_key on node n (cost=0.00..307.75 rows=1 +width=181) + Filter: ((name ~~ '56x%'::text) AND ("type" = 'K'::bpchar) AND +("usage" = 'LIVE'::bpchar)) + -> Seq Scan on job_log j (cost=0.00..75445.54 rows=1 width=288) + Filter: ((job_name = 'COPY FILES'::bpchar) AND (job_start >= +'2005-11-14 00:00:00'::timestamp without time zone) AND ((job_stop <= +'2005-11-14 05:00:00'::timestamp without time zone) OR (job_stop IS NULL))) +(6 rows) + + + explain SELECT n.name, n.type, n.usage + FROM node n + WHERE n.name + LIKE '56x%' + AND n.type = 'K' + AND n.usage = 'LIVE' + AND n.node_id + NOT IN + (SELECT n.node_id + FROM job_log j + INNER JOIN node n + ON j.node_id = n.node_id + WHERE n.name + LIKE '56x%' + AND n.type = 'K' + AND n.usage = 'LIVE' + AND j.job_name = 'COPY FILES' + AND j.job_start >= '2005-11-14 00:00:00' + AND (j.job_stop <= '2005-11-14 05:00:00' OR j.job_stop IS NULL)) + ORDER BY n.name; + + + + + + + + QUERY PLAN +---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- +Index Scan using node_name_key on node n (cost=75451.55..75764.94 rows=1 +width=177) + Filter: ((name ~~ '56x%'::text) AND ("type" = 'K'::bpchar) AND ("usage" = +'LIVE'::bpchar) AND (NOT (hashed subplan))) + SubPlan + -> Nested Loop (cost=0.00..75451.54 rows=1 width=4) + -> Seq Scan on job_log j (cost=0.00..75445.54 rows=1 width=4) + Filter: ((job_name = 'COPY FILES'::bpchar) AND (job_start + >= '2005-11-14 00:00:00'::timestamp without time zone) AND ((job_stop <= +'2005-11-14 05:00:00'::timestamp without time zone) OR (job_stop IS NULL))) + -> Index Scan using node_id_pkey on node n (cost=0.00..5.99 +rows=1 width=4) + Index Cond: ("outer".node_id = n.node_id) + Filter: ((name ~~ '56x%'::text) AND ("type" = 'K'::bpchar) +AND ("usage" = 'LIVE'::bpchar)) + + +Yours, + +Bealach + + +>From: Claus Guttesen <kometen@gmail.com> +>To: Bealach-na Bo <bealach_na_bo@hotmail.com> +>CC: pgsql-performance@postgresql.org +>Subject: Re: [PERFORM] Very slow queries - please help. +>Date: Thu, 24 Nov 2005 14:23:38 +0100 +> +> > Typical query +> > ------------ +> > +> > SELECT n.name +> > FROM node n +> > WHERE n.name +> > LIKE '56x%' +> > AND n.type='H' +> > AND n.usage='TEST' +> > AND n.node_id +> > NOT IN +> > (select n.node_id +> > FROM job_log j +> > INNER JOIN node n +> > ON j.node_id = n.node_id +> > WHERE n.name +> > LIKE '56x%' +> > AND n.type='H' +> > AND n.usage='TEST' +> > AND j.job_name = 'COPY FILES' +> > AND j.job_start >= '2005-11-14 00:00:00' +> > AND (j.job_stop <= '2005-11-22 09:31:10' OR j.job_stop IS NULL)) +> > ORDER BY n.name +> +>Do you have any indexes? +> +>regards +>Claus + + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 11:03:50 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id ECA32D7282 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 11:03:47 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 50669-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 15:03:51 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from soufre.accelance.net (soufre.accelance.net [213.162.48.15]) + by svr1.postgresql.org (Postfix) with ESMTP id 40D82DBCA5 + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 11:03:44 -0400 (AST) +Received: from [213.162.49.207] (gs.team.openwide.fr [213.162.49.207]) + (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) + (No client certificate requested) + by soufre.accelance.net (Postfix) with ESMTP id 4EB4B5CF6; + Thu, 24 Nov 2005 16:03:48 +0100 (CET) +Message-ID: <4385D653.7020804@openwide.fr> +Date: Thu, 24 Nov 2005 16:03:47 +0100 +From: Guillaume Smet <guillaume.smet@openwide.fr> +User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc3 (X11/20050929) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Bealach-na Bo <bealach_na_bo@hotmail.com> +CC: pgsql-performance@postgresql.org +Subject: Re: Very slow queries - please help. +References: <BAY101-F398BCDC77A2C41D225B978AD540@phx.gbl> +In-Reply-To: <BAY101-F398BCDC77A2C41D225B978AD540@phx.gbl> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/495 +X-Sequence-Number: 15752 + +Hi, + +> I'm also sending the EXPLAIN outputs. + +Please provide EXPLAIN ANALYZE outputs instead of EXPLAIN. You will have +more information. + +Indexes on your tables are obviously missing. You should try to add: + +CREATE INDEX idx_node_filter ON node(name, type, usage); +CREATE INDEX idx_job_log_filter ON job_log(job_name, job_start, job_stop); + +I'm not so sure it's a good idea to add job_stop in this index as you +have an IS NULL in your query so I'm not sure it can be used. You should +try it anyway and remove it if not needed. + +I added all your search fields in the indexes but it depends a lot on +the selectivity of your conditions. I don't know your data but I think +you understand the idea. + +HTH + +-- +Guillaume + +From pgsql-performance-owner@postgresql.org Thu Nov 24 11:15:38 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 6D425D7282 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 11:15:37 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 49929-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 15:15:40 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 841E3DBC1D + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 11:15:34 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAOFFZYR013627; + Thu, 24 Nov 2005 10:15:35 -0500 (EST) +To: "Bealach-na Bo" <bealach_na_bo@hotmail.com> +cc: pgsql-performance@postgresql.org +Subject: Re: Very slow queries - please help. +In-reply-to: <BAY101-F89F00F81CBAF5B66A6EE0AD540@phx.gbl> +References: <BAY101-F89F00F81CBAF5B66A6EE0AD540@phx.gbl> +Comments: In-reply-to "Bealach-na Bo" <bealach_na_bo@hotmail.com> + message dated "Thu, 24 Nov 2005 13:06:48 +0000" +Date: Thu, 24 Nov 2005 10:15:35 -0500 +Message-ID: <13626.1132845335@sss.pgh.pa.us> +From: Tom Lane <tgl@sss.pgh.pa.us> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.005 required=5 tests=[AWL=0.005] +X-Spam-Score: 0.005 +X-Spam-Level: +X-Archive-Number: 200511/496 +X-Sequence-Number: 15753 + +"Bealach-na Bo" <bealach_na_bo@hotmail.com> writes: +> I'm having great difficulties getting the performance I had hoped for +> from Postgresql 8.0. The typical query below takes ~20 minutes !! + +You need to show us the table definition (including indexes) and the +EXPLAIN ANALYZE results for the query. + +It seems likely that the NOT IN is the source of your problems, +but it's hard to be sure without EXPLAIN results. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Thu Nov 24 11:37:20 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 63B3EDBBF3 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 11:37:19 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 56923-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 15:37:23 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 9400CDBB89 + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 11:37:16 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAOFbLhL013838; + Thu, 24 Nov 2005 10:37:21 -0500 (EST) +To: Vipul.Gupta@trilogy.com +cc: pgsql-performance@postgresql.org +Subject: Re: xlog flush request error +In-reply-to: <OF52A26328.BA64DC8C-ON862570C3.00440956@trilogy.com> +References: <OF52A26328.BA64DC8C-ON862570C3.00440956@trilogy.com> +Comments: In-reply-to Vipul.Gupta@trilogy.com + message dated "Thu, 24 Nov 2005 06:24:32 -0600" +Date: Thu, 24 Nov 2005 10:37:21 -0500 +Message-ID: <13837.1132846641@sss.pgh.pa.us> +From: Tom Lane <tgl@sss.pgh.pa.us> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.005 required=5 tests=[AWL=0.005] +X-Spam-Score: 0.005 +X-Spam-Level: +X-Archive-Number: 200511/497 +X-Sequence-Number: 15754 + +Vipul.Gupta@trilogy.com writes: +> Can anyone suggest how do i fix this + +> xlog flush request 7/7D02338C is not satisfied --- flushed only to +> 3/2471E324 + +This looks like corrupt data to me --- specifically, garbage in the LSN +field of a page header. Is that all you get? PG 7.4 and up should tell +you the problem page number in a CONTEXT: line. + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Thu Nov 24 12:00:48 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 2D3F2DBCB3 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 12:00:47 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 58710-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 16:00:45 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from stark.xeocode.com (stark.xeocode.com [216.58.44.227]) + by svr1.postgresql.org (Postfix) with ESMTP id 6BCB0DBCC9 + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 12:00:44 -0400 (AST) +Received: from localhost ([127.0.0.1] helo=stark.xeocode.com) + by stark.xeocode.com with smtp (Exim 3.36 #1 (Debian)) + id 1EfJWM-000338-00; Thu, 24 Nov 2005 11:00:26 -0500 +To: Mark Kirkwood <markir@paradise.net.nz> +Cc: Luke Lonergan <llonergan@greenplum.com>, stange@rentec.com, + Greg Stark <gsstark@mit.edu>, Dave Cramer <pg@fastcrypt.com>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFAAB702.1460D%llonergan@greenplum.com> + <438583C8.4050809@paradise.net.nz> +In-Reply-To: <438583C8.4050809@paradise.net.nz> +From: Greg Stark <gsstark@mit.edu> +Organization: The Emacs Conspiracy; member since 1992 +Date: 24 Nov 2005 11:00:25 -0500 +Message-ID: <87d5kqkpd2.fsf@stark.xeocode.com> +Lines: 24 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/498 +X-Sequence-Number: 15755 + +Mark Kirkwood <markir@paradise.net.nz> writes: + +> Yeah - it's pretty clear that the count aggregate is fairly expensive wrt cpu - +> However, I am not sure if all agg nodes suffer this way (guess we could try a +> trivial aggregate that does nothing for all tuples bar the last and just +> reports the final value it sees). + +As you mention count(*) and count(1) are the same thing. + +Last I heard the reason count(*) was so expensive was because its state +variable was a bigint. That means it doesn't fit in a Datum and has to be +alloced and stored as a pointer. And because of the Aggregate API that means +it has to be allocated and freed for every tuple processed. + +There was some talk of having a special case API for count(*) and maybe +sum(...) to avoid having to do this. + +There was also some talk of making Datum 8 bytes wide on platforms where that +was natural (I guess AMD64, Sparc64, Alpha, Itanic). + +Afaik none of these items have happened but I don't know for sure. + +-- +greg + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 12:25:50 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id DB93CDBC1D + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 12:25:49 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 63202-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 16:25:47 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id A76AFDBC0C + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 12:25:46 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAOGPSnR014287; + Thu, 24 Nov 2005 11:25:29 -0500 (EST) +To: Greg Stark <gsstark@mit.edu> +cc: Mark Kirkwood <markir@paradise.net.nz>, + Luke Lonergan <llonergan@greenplum.com>, stange@rentec.com, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <87d5kqkpd2.fsf@stark.xeocode.com> +References: <BFAAB702.1460D%llonergan@greenplum.com> + <438583C8.4050809@paradise.net.nz> + <87d5kqkpd2.fsf@stark.xeocode.com> +Comments: In-reply-to Greg Stark <gsstark@mit.edu> + message dated "24 Nov 2005 11:00:25 -0500" +Date: Thu, 24 Nov 2005 11:25:28 -0500 +Message-ID: <14286.1132849528@sss.pgh.pa.us> +From: Tom Lane <tgl@sss.pgh.pa.us> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.004 required=5 tests=[AWL=0.004] +X-Spam-Score: 0.004 +X-Spam-Level: +X-Archive-Number: 200511/499 +X-Sequence-Number: 15756 + +Greg Stark <gsstark@mit.edu> writes: +> Last I heard the reason count(*) was so expensive was because its state +> variable was a bigint. That means it doesn't fit in a Datum and has to be +> alloced and stored as a pointer. And because of the Aggregate API that means +> it has to be allocated and freed for every tuple processed. + +There's a hack in 8.1 to avoid the palloc overhead (courtesy of Neil +Conway IIRC). + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Thu Nov 24 12:40:29 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 88B15DBA4C + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 12:40:28 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 64887-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 16:40:26 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from stark.xeocode.com (stark.xeocode.com [216.58.44.227]) + by svr1.postgresql.org (Postfix) with ESMTP id E59F2DBA3F + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 12:40:25 -0400 (AST) +Received: from localhost ([127.0.0.1] helo=stark.xeocode.com) + by stark.xeocode.com with smtp (Exim 3.36 #1 (Debian)) + id 1EfK8z-0003u4-00; Thu, 24 Nov 2005 11:40:21 -0500 +To: Tom Lane <tgl@sss.pgh.pa.us> +Cc: Greg Stark <gsstark@mit.edu>, Mark Kirkwood <markir@paradise.net.nz>, + Luke Lonergan <llonergan@greenplum.com>, stange@rentec.com, + Dave Cramer <pg@fastcrypt.com>, Joshua Marsh <icub3d@gmail.com>, + pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFAAB702.1460D%llonergan@greenplum.com> + <438583C8.4050809@paradise.net.nz> <87d5kqkpd2.fsf@stark.xeocode.com> + <14286.1132849528@sss.pgh.pa.us> +In-Reply-To: <14286.1132849528@sss.pgh.pa.us> +From: Greg Stark <gsstark@mit.edu> +Organization: The Emacs Conspiracy; member since 1992 +Date: 24 Nov 2005 11:40:21 -0500 +Message-ID: <877jayknii.fsf@stark.xeocode.com> +Lines: 15 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/500 +X-Sequence-Number: 15757 + +Tom Lane <tgl@sss.pgh.pa.us> writes: + +> Greg Stark <gsstark@mit.edu> writes: +> > Last I heard the reason count(*) was so expensive was because its state +> > variable was a bigint. That means it doesn't fit in a Datum and has to be +> > alloced and stored as a pointer. And because of the Aggregate API that means +> > it has to be allocated and freed for every tuple processed. +> +> There's a hack in 8.1 to avoid the palloc overhead (courtesy of Neil +> Conway IIRC). + +ah, cool, missed that. + +-- +greg + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 13:08:00 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8558CDBC26 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 13:07:59 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 69156-03-2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 17:07:57 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw01.mi8.com [63.240.6.47]) + by svr1.postgresql.org (Postfix) with ESMTP id 91589DBBB8 + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 13:07:56 -0400 (AST) +Received: from 172.16.1.112 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D1)); Thu, 24 Nov 2005 12:07:42 -0500 +X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Thu, 24 Nov + 2005 12:07:42 -0500 +Received: from 208.54.15.129 ([208.54.15.129]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.106]) with Microsoft Exchange Server HTTP-DAV ; Thu, 24 Nov + 2005 12:07:42 -0500 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Thu, 24 Nov 2005 09:07:40 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Luke Lonergan" <llonergan@greenplum.com> +cc: pgsql-performance@postgresql.org +Message-ID: <BFAB335C.14684%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXvIxdwfLDwWrP8Q669kHxJ85F1twBrF12iABKHo1c= +In-Reply-To: <BFAAB702.1460D%llonergan@greenplum.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 24 Nov 2005 17:07:42.0594 (UTC) + FILETIME=[94FBE620:01C5F119] +X-WSS-ID: 6F9B2CD43282685473-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=2.386 required=5 tests=[AWL=-0.103, + RCVD_IN_SORBS_WEB=1.236, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 2.386 +X-Spam-Level: ** +X-Archive-Number: 200511/501 +X-Sequence-Number: 15758 + +The same 12.9GB distributed across 4 machines using Bizgres MPP fits into +I/O cache. The interesting result is that the query "select count(1)" is +limited in speed to 280 MB/s per CPU when run on the lineitem table. So +when I run it spread over 4 machines, one CPU per machine I get this: + +====================================================== +Bizgres MPP, 4 data segments, 1 per 2 CPUs +====================================================== +llonergan=# explain select count(1) from lineitem; + QUERY PLAN +---------------------------------------------------------------------------- +---------- + Aggregate (cost=582452.00..582452.00 rows=1 width=0) + -> Gather Motion (cost=582452.00..582452.00 rows=1 width=0) + -> Aggregate (cost=582452.00..582452.00 rows=1 width=0) + -> Seq Scan on lineitem (cost=0.00..544945.00 rows=15002800 +width=0) +(4 rows) + +llonergan=# \timing +Timing is on. +llonergan=# select count(1) from lineitem; + count +---------- + 59986052 +(1 row) + +Time: 12191.435 ms +llonergan=# select count(1) from lineitem; + count +---------- + 59986052 +(1 row) + +Time: 11986.109 ms +llonergan=# select count(1) from lineitem; + count +---------- + 59986052 +(1 row) + +Time: 11448.941 ms +====================================================== + +That's 12,937 MB in 11.45 seconds, or 1,130 MB/s. When you divide out the +number of Postgres instances (4), that's 283MB/s per Postgres instance. + +To verify that this has nothing to do with MPP, I ran it in a special +internal mode on one instance and got the same result. + +So - we should be able to double this rate by running one segment per CPU, +or two per host: + +====================================================== +Bizgres MPP, 8 data segments, 1 per CPU +====================================================== +llonergan=# select count(1) from lineitem; + count +---------- + 59986052 +(1 row) + +Time: 6484.594 ms +llonergan=# select count(1) from lineitem; + count +---------- + 59986052 +(1 row) + +Time: 6156.729 ms +llonergan=# select count(1) from lineitem; + count +---------- + 59986052 +(1 row) + +Time: 6063.416 ms +====================================================== +That's 12,937 MB in 11.45 seconds, or 2,134 MB/s. When you divide out the +number of Postgres instances (8), that's 267MB/s per Postgres instance. + +So, if you want to "select count(1)", using more CPUs is a good idea! For +most complex queries, having lots of CPUs + MPP is a good combo. + +Here is an example of a sorting plan - this should probably be done with a +hash aggregation, but using 8 CPUs makes it go 8x faster: + + +- Luke + + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 14:14:57 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 46F38DBC44 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 14:14:56 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 76107-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 18:14:54 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from hotmail.com (bay101-f35.bay101.hotmail.com [64.4.56.45]) + by svr1.postgresql.org (Postfix) with ESMTP id 1ABCCDBC0C + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 14:14:52 -0400 (AST) +Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; + Thu, 24 Nov 2005 10:14:53 -0800 +Message-ID: <BAY101-F35C5475BF7CCEE56EAB208AD540@phx.gbl> +Received: from 64.4.56.200 by by101fd.bay101.hotmail.msn.com with HTTP; + Thu, 24 Nov 2005 18:14:53 GMT +X-Originating-IP: [84.210.10.106] +X-Originating-Email: [bealach_na_bo@hotmail.com] +X-Sender: bealach_na_bo@hotmail.com +From: "Bealach-na Bo" <bealach_na_bo@hotmail.com> +To: kometen@gmail.com, tgl@sss.pgh.pa.us, noerder-tuitje@technology.de, + pgsql-performance@postgresql.org, guillaume.smet@openwide.fr +Subject: Re: Very slow queries - please help +Date: Thu, 24 Nov 2005 18:14:53 +0000 +Mime-Version: 1.0 +Content-Type: text/plain; format=flowed +X-OriginalArrivalTime: 24 Nov 2005 18:14:53.0308 (UTC) + FILETIME=[F77A0BC0:01C5F122] +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.439 required=5 tests=[AWL=-0.480, + DNS_FROM_RFC_ABUSE=0.479, DNS_FROM_RFC_POST=1.44, + MSGID_FROM_MTA_HEADER=0] +X-Spam-Score: 1.439 +X-Spam-Level: * +X-Archive-Number: 200511/502 +X-Sequence-Number: 15759 + +OK. + +The consensus seems to be that I need more indexes and I also need to +look into the NOT IN statement as a possible bottleneck. I've +introduced the indexes which has led to a DRAMATIC change in response +time. Now I have to experiment with INNER JOIN -> OUTER JOIN +variations, SET ENABLE_SEQSCAN=OFF. + +Forgive me for not mentioning each person individually and by name. +You have all contributed to confirming what I had suspected (and +hoped): that *I* have a lot to learn! + +I'm attaching table descriptions, the first few lines of top output +while the queries were running, index lists, sample queries and +EXPLAIN ANALYSE output BEFORE and AFTER the introduction of the +indexes. As I said, DRAMATIC :) I notice that the CPU usage does not +vary very much, it's nearly 100% anyway, but the memory usage drops +markedly, which is another very nice result of the index introduction. + +Any more comments and tips would be very welcome. + +Thank you all for your input. + +Bealach. + + + + +blouser@10.0.0.2.dbdev=> \d job_log + Table "blouser.job_log" + Column | Type | Modifiers +----------------+-----------------------------+-------------------------------------------------- +job_log_id | integer | not null default +nextval('job_log_id_seq'::text) +first_registry | timestamp without time zone | +blogger_name | character(50) | +node_id | integer | +job_type | character(50) | +job_name | character(256) | +job_start | timestamp without time zone | +job_timeout | interval | +job_stop | timestamp without time zone | +nfiles_in_job | integer | +status | integer | +error_code | smallint | +Indexes: + "job_log_id_pkey" PRIMARY KEY, btree (job_log_id) +Check constraints: + "job_log_status_check" CHECK (status = 0 OR status = 1 OR status = 8 OR +status = 9) +Foreign-key constraints: + "legal_node" FOREIGN KEY (node_id) REFERENCES node(node_id) + + + + + +blouser@10.0.0.2.dbdev=> \d node + Table "blouser.node" +Column | Type | Modifiers +---------+---------------+----------------------------------------------- +node_id | integer | not null default nextval('node_id_seq'::text) +name | character(50) | +type | character(1) | +usage | character(4) | +Indexes: + "node_id_pkey" PRIMARY KEY, btree (node_id) + "node_name_key" UNIQUE, btree (name) +Check constraints: + "node_type_check" CHECK ("type" = 'B'::bpchar OR "type" = 'K'::bpchar OR +"type" = 'C'::bpchar OR "type" = 'T'::bpchar OR "type" = 'R'::bpchar) + "node_usage_check" CHECK ("usage" = 'TEST'::bpchar OR "usage" = +'LIVE'::bpchar) + + +#========================before new indexes were created + + +Tasks: 114 total, 2 running, 112 sleeping, 0 stopped, 0 zombie +Cpu(s): 25.7% us, 24.5% sy, 0.0% ni, 49.4% id, 0.3% wa, 0.0% hi, 0.0% si +Mem: 1554788k total, 1513576k used, 41212k free, 31968k buffers +Swap: 1020024k total, 27916k used, 992108k free, 708728k cached + + PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND +25883 postgres 25 0 20528 12m 11m R 99.7 0.8 4:54.91 postmaster + + + + + +blouser@10.0.0.2.dbdev=> \di + List of relations +Schema | Name | Type | Owner | Table +---------+-----------------+-------+---------+--------- +blouser | job_log_id_pkey | index | blouser | job_log +blouser | node_id_pkey | index | blouser | node +blouser | node_name_key | index | blouser | node +(3 rows) + + + EXPLAIN ANALYSE SELECT n.name,n.type, + n.usage, j.status, + j.job_start,j.job_stop, + j.nfiles_in_job,j.job_name + FROM job_log j + INNER JOIN node n + ON j.node_id = n.node_id + WHERE n.name + LIKE '711%' + AND n.type = 'K' + AND n.usage = 'LIVE' + AND j.job_name = 'COPY FILES' + AND j.job_start >= '2005-11-14 00:00:00' + AND (j.job_stop <= '2005-11-14 05:00:00' OR j.job_stop IS NULL) + ORDER BY n.name; + + + QUERY PLAN +----------------------------------------------------------------------------------------------------------------------------------- +Nested Loop (cost=0.00..75753.31 rows=1 width=461) (actual +time=270486.692..291662.350 rows=3 loops=1) + Join Filter: ("inner".node_id = "outer".node_id) + -> Index Scan using node_name_key on node n (cost=0.00..307.75 rows=1 +width=181) (actual time=0.135..11.034 rows=208 loops=1) + Filter: ((name ~~ '711%'::text) AND ("type" = 'K'::bpchar) AND +("usage" = 'LIVE'::bpchar)) + -> Seq Scan on job_log j (cost=0.00..75445.54 rows=1 width=288) (actual +time=273.374..1402.089 rows=22 loops=208) + Filter: ((job_name = 'COPY FILES'::bpchar) AND (job_start >= +'2005-11-14 00:00:00'::timestamp without time zone) AND ((job_stop <= +'2005-11-14 05:00:00'::timestamp without time zone) OR (job_stop IS NULL))) +Total runtime: 291662.482 ms +(7 rows) + + + EXPLAIN ANALYSE SELECT n.name, n.type, n.usage + FROM node n + WHERE n.name + LIKE '56x%' + AND n.type = 'K' + AND n.usage = 'LIVE' + AND n.node_id NOT IN + (SELECT n.node_id + FROM job_log j + INNER JOIN node n + ON j.node_id = n.node_id + WHERE n.name + LIKE '711%' + AND n.type = 'K' + AND n.usage = 'LIVE' + AND j.job_name = 'COPY FILES' + AND j.job_start >= '2005-11-14 00:00:00' + AND (j.job_stop <= '2005-11-14 05:00:00' OR j.job_stop IS NULL)) + ORDER BY n.name; + + + + QUERY PLAN +------------------------------------------------------------------------------------------------------------------------------------ +Index Scan using node_name_key on node n (cost=75451.55..75764.94 rows=1 +width=177) (actual time=1394.617..1398.609 rows=205 loops=1) + Filter: ((name ~~ '56x%'::text) AND ("type" = 'K'::bpchar) AND ("usage" = +'LIVE'::bpchar) AND (NOT (hashed subplan))) + SubPlan + -> Nested Loop (cost=0.00..75451.54 rows=1 width=4) (actual +time=1206.622..1394.462 rows=3 loops=1) + -> Seq Scan on job_log j (cost=0.00..75445.54 rows=1 width=4) +(actual time=271.361..1393.363 rows=22 loops=1) + Filter: ((job_name = 'COPY FILES'::bpchar) AND (job_start + >= '2005-11-14 00:00:00'::timestamp without time zone) AND ((job_stop <= +'2005-11-14 05:00:00'::timestamp without time zone) OR (job_stop IS NULL))) + -> Index Scan using node_id_pkey on node n (cost=0.00..5.99 +rows=1 width=4) (actual time=0.042..0.042 rows=0 loops=22) + Index Cond: ("outer".node_id = n.node_id) + Filter: ((name ~~ '711%'::text) AND ("type" = 'K'::bpchar) +AND ("usage" = 'LIVE'::bpchar)) +Total runtime: 1398.868 ms +(10 rows) + + + + +#===================================after the new indexes were created + +Tasks: 114 total, 2 running, 112 sleeping, 0 stopped, 0 zombie +Cpu(s): 22.9% us, 27.2% sy, 0.0% ni, 49.7% id, 0.0% wa, 0.2% hi, 0.0% si +Mem: 1554788k total, 1414632k used, 140156k free, 14784k buffers +Swap: 1020024k total, 28008k used, 992016k free, 623652k cached + + PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND +26409 postgres 25 0 21580 8684 7116 R 99.9 0.6 0:25.38 postmaster + + + +Schema | Name | Type | Owner | Table +---------+--------------------+-------+---------+--------- +blouser | idx_job_log_filter | index | blouser | job_log +blouser | idx_node_filter | index | blouser | node +blouser | job_log_id_pkey | index | blouser | job_log +blouser | node_id_pkey | index | blouser | node +blouser | node_name_key | index | blouser | node +(5 rows) + + + EXPLAIN ANALYSE SELECT n.name,n.type, + n.usage, j.status, + j.job_start,j.job_stop, + j.nfiles_in_job,j.job_name + FROM job_log j + INNER JOIN node n + ON j.node_id = n.node_id + WHERE n.name + LIKE '711%' + AND n.type = 'K' + AND n.usage = 'LIVE' + AND j.job_name = 'COPY FILES' + AND j.job_start >= '2005-11-14 00:00:00' + AND (j.job_stop <= '2005-11-14 05:00:00' OR j.job_stop IS NULL) + ORDER BY n.name; + + +---------------------------------------------------------------------------------------------------------------------------------------------------- +Sort (cost=18049.23..18049.23 rows=1 width=461) (actual +time=223.540..223.543 rows=3 loops=1) + Sort Key: n.name + -> Nested Loop (cost=0.00..18049.22 rows=1 width=461) (actual +time=201.575..223.470 rows=3 loops=1) + -> Index Scan using idx_job_log_filter on job_log j +(cost=0.00..18043.21 rows=1 width=288) (actual time=52.567..222.855 rows=22 +loops=1) + Index Cond: ((job_name = 'COPY FILES'::bpchar) AND (job_start + >= '2005-11-14 00:00:00'::timestamp without time zone)) + Filter: ((job_stop <= '2005-11-14 05:00:00'::timestamp +without time zone) OR (job_stop IS NULL)) + -> Index Scan using node_id_pkey on node n (cost=0.00..5.99 +rows=1 width=181) (actual time=0.022..0.022 rows=0 loops=22) + Index Cond: ("outer".node_id = n.node_id) + Filter: ((name ~~ '711%'::text) AND ("type" = 'K'::bpchar) +AND ("usage" = 'LIVE'::bpchar)) +Total runtime: 223.677 ms +(10 rows) + + + + EXPLAIN ANALYSE SELECT n.name, n.type, n.usage + FROM node n + WHERE n.name + LIKE '56x%' + AND n.type = 'K' + AND n.usage = 'LIVE' + AND n.node_id NOT IN + (SELECT n.node_id + FROM job_log j + INNER JOIN node n + ON j.node_id = n.node_id + WHERE n.name + LIKE '711%' + AND n.type = 'K' + AND n.usage = 'LIVE' + AND j.job_name = 'COPY FILES' + AND j.job_start >= '2005-11-14 00:00:00' + AND (j.job_stop <= '2005-11-14 05:00:00' OR j.job_stop IS NULL)) + ORDER BY n.name; + + + +QUERY PLAN +----------------------------------------------------------------------------------------------------------------------------------------------------------- +Sort (cost=18141.89..18141.89 rows=1 width=177) (actual +time=223.495..223.627 rows=205 loops=1) + Sort Key: name + -> Seq Scan on node n (cost=18049.22..18141.88 rows=1 width=177) +(actual time=220.293..222.526 rows=205 loops=1) + Filter: ((name ~~ '56x%'::text) AND ("type" = 'K'::bpchar) AND +("usage" = 'LIVE'::bpchar) AND (NOT (hashed subplan))) + SubPlan + -> Nested Loop (cost=0.00..18049.22 rows=1 width=4) (actual +time=198.343..220.195 rows=3 loops=1) + -> Index Scan using idx_job_log_filter on job_log j +(cost=0.00..18043.21 rows=1 width=4) (actual time=50.748..219.741 rows=22 +loops=1) + Index Cond: ((job_name = 'COPY FILES'::bpchar) AND +(job_start >= '2005-11-14 00:00:00'::timestamp without time zone)) + Filter: ((job_stop <= '2005-11-14 +05:00:00'::timestamp without time zone) OR (job_stop IS NULL)) + -> Index Scan using node_id_pkey on node n +(cost=0.00..5.99 rows=1 width=4) (actual time=0.015..0.016 rows=0 loops=22) + Index Cond: ("outer".node_id = n.node_id) + Filter: ((name ~~ '711%'::text) AND ("type" = +'K'::bpchar) AND ("usage" = 'LIVE'::bpchar)) +Total runtime: 223.860 ms +(13 rows) + + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 14:51:45 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D0A58D838E + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 14:51:44 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 84659-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 18:51:44 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from hotmail.com (bay101-f8.bay101.hotmail.com [64.4.56.18]) + by svr1.postgresql.org (Postfix) with ESMTP id 3F56DD7945 + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 14:51:42 -0400 (AST) +Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; + Thu, 24 Nov 2005 10:51:42 -0800 +Message-ID: <BAY101-F89370E7A3812718A5D240AD540@phx.gbl> +Received: from 64.4.56.200 by by101fd.bay101.hotmail.msn.com with HTTP; + Thu, 24 Nov 2005 18:51:42 GMT +X-Originating-IP: [84.210.10.106] +X-Originating-Email: [bealach_na_bo@hotmail.com] +X-Sender: bealach_na_bo@hotmail.com +From: "Bealach-na Bo" <bealach_na_bo@hotmail.com> +To: pgsql-performance@postgresql.org +Subject: Very slow queries - please help +Date: Thu, 24 Nov 2005 18:51:42 +0000 +Mime-Version: 1.0 +Content-Type: text/plain; format=flowed +X-OriginalArrivalTime: 24 Nov 2005 18:51:42.0967 (UTC) + FILETIME=[1C894070:01C5F128] +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.439 required=5 tests=[AWL=-0.480, + DNS_FROM_RFC_ABUSE=0.479, DNS_FROM_RFC_POST=1.44, + MSGID_FROM_MTA_HEADER=0] +X-Spam-Score: 1.439 +X-Spam-Level: * +X-Archive-Number: 200511/503 +X-Sequence-Number: 15760 + +A quick note to say that I'm very grateful for Tom Lane's input also. +Tom, I did put you on the list of recipients for my last posting to +pgsql-performance, but got: + + +--------------------cut here-------------------- +This is an automatically generated Delivery Status Notification. + +Delivery to the following recipients failed. + + tgl@sss.pgh.pa.us + + + +Many regards, + +Bealach + + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 18:08:03 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D973BDBD00 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 18:08:01 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 06557-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 22:08:03 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from linda-1.paradise.net.nz (bm-1a.paradise.net.nz + [203.96.152.180]) + by svr1.postgresql.org (Postfix) with ESMTP id 1DC67DBCCA + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 18:07:59 -0400 (AST) +Received: from smtp-1.paradise.net.nz + (tclsnelb1-src-1.paradise.net.nz [203.96.152.172]) by + linda-1.paradise.net.nz (Paradise.net.nz) with ESMTP id + <0IQH00L32C5AXK@linda-1.paradise.net.nz> for + pgsql-performance@postgresql.org; Fri, 25 Nov 2005 11:08:00 +1300 (NZDT) +Received: from [192.168.1.11] (218-101-28-43.dsl.clear.net.nz [218.101.28.43]) + by smtp-1.paradise.net.nz (Postfix) with ESMTP id 56F1EEF76AF; Fri, + 25 Nov 2005 11:07:52 +1300 (NZDT) +Date: Fri, 25 Nov 2005 11:07:50 +1300 +From: Mark Kirkwood <markir@paradise.net.nz> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <14286.1132849528@sss.pgh.pa.us> +To: Tom Lane <tgl@sss.pgh.pa.us> +Cc: Greg Stark <gsstark@mit.edu>, Luke Lonergan <llonergan@greenplum.com>, + stange@rentec.com, Dave Cramer <pg@fastcrypt.com>, + Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org +Message-id: <438639B6.5090902@paradise.net.nz> +MIME-version: 1.0 +Content-type: text/plain; format=flowed; charset=ISO-8859-1 +Content-transfer-encoding: 7bit +X-Accept-Language: en-us, en +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20051106) +References: <BFAAB702.1460D%llonergan@greenplum.com> + <438583C8.4050809@paradise.net.nz> <87d5kqkpd2.fsf@stark.xeocode.com> + <14286.1132849528@sss.pgh.pa.us> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.176 required=5 tests=[AWL=0.176] +X-Spam-Score: 0.176 +X-Spam-Level: +X-Archive-Number: 200511/504 +X-Sequence-Number: 15761 + +Tom Lane wrote: +> Greg Stark <gsstark@mit.edu> writes: +> +>>Last I heard the reason count(*) was so expensive was because its state +>>variable was a bigint. That means it doesn't fit in a Datum and has to be +>>alloced and stored as a pointer. And because of the Aggregate API that means +>>it has to be allocated and freed for every tuple processed. +> +> +> There's a hack in 8.1 to avoid the palloc overhead (courtesy of Neil +> Conway IIRC). +> + +It certainly makes quite a difference as I measure it: + +doing select(1) from a 181000 page table (completely uncached) on my PIII: + +8.0 : 32 s +8.1 : 25 s + +Note that the 'fastcount()' function takes 21 s in both cases - so all +the improvement seems to be from the count overhead reduction. + +Cheers + +Mark + + + + + + + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 20:03:10 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 16AEADBA23 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 20:03:09 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 44818-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 00:03:10 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.rilk.com (mail.rilk.com [193.19.217.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 0C23CDBD11 + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 19:34:32 -0400 (AST) +Received: from [192.168.0.1] (cev75-1-81-57-249-136.fbx.proxad.net + [81.57.249.136]) (authenticated bits=0) + by mail.rilk.com (8.13.0/8.13.0) with ESMTP id jAONYIjo028081 + (version=TLSv1/SSLv3 cipher=EDH-DSS-DES-CBC3-SHA bits=168 verify=NO) + for <pgsql-performance@postgresql.org>; + Fri, 25 Nov 2005 00:34:32 +0100 (CET) +Mime-Version: 1.0 (Apple Message framework v746.2) +In-Reply-To: <334D9941-B5B3-4D18-8312-F85D0FB054ED@rilk.com> +References: <334D9941-B5B3-4D18-8312-F85D0FB054ED@rilk.com> +Content-Type: text/plain; charset=ISO-8859-1; delsp=yes; format=flowed +Message-Id: <A6F55E12-4479-49F6-B3EE-8CFCC8541179@rilk.com> +Content-Transfer-Encoding: quoted-printable +From: Pailloncy Jean-Gerard <jg@rilk.com> +Subject: Re: 8.1 count(*) distinct: IndexScan/SeqScan +Date: Fri, 25 Nov 2005 00:34:16 +0100 +To: pgsql-performance@postgresql.org +X-Mailer: Apple Mail (2.746.2) +X-DCC-NIET-Metrics: mail.rilk.com 1080; env_From=1 Body=1 Fuz1=1 Fuz2=1 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/505 +X-Sequence-Number: 15762 + +I redo the test, with a freshly installed data directory. Same result. + +Note: This is the full log. I just suppress the mistake I do like =20 +"sl" for "ls". + +Jean-G=E9rard Pailloncy + + +Last login: Thu Nov 24 12:52:32 2005 from 192.168.0.1 +OpenBSD 3.8 (WDT) #2: Tue Nov 8 00:52:38 CET 2005 + +Welcome to OpenBSD: The proactively secure Unix-like operating system. + +Please use the sendbug(1) utility to report bugs in the system. +Before reporting a bug, please try to reproduce it with the latest +version of the code. With bug reports, please try to ensure that +enough information to reproduce the problem is enclosed, and if a +known fix for it exists, include that as well. + +Terminal type? [xterm-color] +# cd /mnt2/pg/install/bin/ +# mkdir /mnt2/pg/data +# chown -R _pgsql:_pgsql /mnt2/pg/data +# su _pgsql +$ ls +clusterdb droplang pg_config pg_resetxlog =20 +reindexdb +createdb dropuser pg_controldata pg_restore =20 +vacuumdb +createlang ecpg pg_ctl postgres +createuser initdb pg_dump postmaster +dropdb ipcclean pg_dumpall psql +$ ./initdb -D /mnt2/pg/data +The files belonging to this database system will be owned by user =20 +"_pgsql". +This user must also own the server process. + +The database cluster will be initialized with locale C. + +fixing permissions on existing directory /mnt2/pg/data ... ok +creating directory /mnt2/pg/data/global ... ok +creating directory /mnt2/pg/data/pg_xlog ... ok +creating directory /mnt2/pg/data/pg_xlog/archive_status ... ok +creating directory /mnt2/pg/data/pg_clog ... ok +creating directory /mnt2/pg/data/pg_subtrans ... ok +creating directory /mnt2/pg/data/pg_twophase ... ok +creating directory /mnt2/pg/data/pg_multixact/members ... ok +creating directory /mnt2/pg/data/pg_multixact/offsets ... ok +creating directory /mnt2/pg/data/base ... ok +creating directory /mnt2/pg/data/base/1 ... ok +creating directory /mnt2/pg/data/pg_tblspc ... ok +selecting default max_connections ... 100 +selecting default shared_buffers ... 1000 +creating configuration files ... ok +creating template1 database in /mnt2/pg/data/base/1 ... ok +initializing pg_authid ... ok +enabling unlimited row size for system tables ... ok +initializing dependencies ... ok +creating system views ... ok +loading pg_description ... ok +creating conversions ... ok +setting privileges on built-in objects ... ok +creating information schema ... ok +vacuuming database template1 ... ok +copying template1 to template0 ... ok +copying template1 to postgres ... ok + +WARNING: enabling "trust" authentication for local connections +You can change this by editing pg_hba.conf or using the -A option the +next time you run initdb. + +Success. You can now start the database server using: + + ./postmaster -D /mnt2/pg/data +or + ./pg_ctl -D /mnt2/pg/data -l logfile start + +$ ./pg_ctl -D /mnt2/pg/data -l /mnt2/pg/data/logfile start +postmaster starting +$ ./psql postgres +Welcome to psql 8.1.0, the PostgreSQL interactive terminal. + +Type: \copyright for distribution terms + \h for help with SQL commands + \? for help with psql commands + \g or terminate with semicolon to execute query + \q to quit + +postgres=3D# create table test (id serial, val integer); +NOTICE: CREATE TABLE will create implicit sequence "test_id_seq" for =20= + +serial column "test.id" +CREATE TABLE +postgres=3D# create unique index testid on test (id); +CREATE INDEX +postgres=3D# create index testval on test (val); +CREATE INDEX +postgres=3D# insert into test (val) values (round(random()=20 +*1024*1024*1024)); +INSERT 0 1 +postgres=3D# vacuum full analyze; +VACUUM +postgres=3D# select count(1) from test; +count +------- + 1 +(1 row) + +postgres=3D# explain select count(*) from (select distinct on (val) * =20= + +from test) as foo; + QUERY PLAN +---------------------------------------------------------------------- +Aggregate (cost=3D1.04..1.05 rows=3D1 width=3D0) + -> Unique (cost=3D1.02..1.03 rows=3D1 width=3D8) + -> Sort (cost=3D1.02..1.02 rows=3D1 width=3D8) + Sort Key: test.val + -> Seq Scan on test (cost=3D0.00..1.01 rows=3D1 = +width=3D8) +(5 rows) + +postgres=3D# insert into test (val) select round(random()=20 +*1024*1024*1024) from test; +INSERT 0 1 +postgres=3D# insert into test (val) select round(random()=20 +*1024*1024*1024) from test; +INSERT 0 2 +postgres=3D# insert into test (val) select round(random()=20 +*1024*1024*1024) from test; +INSERT 0 4 +postgres=3D# insert into test (val) select round(random()=20 +*1024*1024*1024) from test; +INSERT 0 8 +postgres=3D# insert into test (val) select round(random()=20 +*1024*1024*1024) from test; +INSERT 0 16 +postgres=3D# insert into test (val) select round(random()=20 +*1024*1024*1024) from test; +INSERT 0 32 +postgres=3D# vacuum full analyze; +VACUUM +postgres=3D# explain select count(*) from (select distinct on (val) * =20= + +from test) as foo; + QUERY PLAN +----------------------------------------------------------------------- +Aggregate (cost=3D4.68..4.69 rows=3D1 width=3D0) + -> Unique (cost=3D3.56..3.88 rows=3D64 width=3D8) + -> Sort (cost=3D3.56..3.72 rows=3D64 width=3D8) + Sort Key: test.val + -> Seq Scan on test (cost=3D0.00..1.64 rows=3D64 = +width=3D8) +(5 rows) + +postgres=3D# insert into test (val) select round(random()=20 +*1024*1024*1024) from test; +INSERT 0 64 +postgres=3D# insert into test (val) select round(random()=20 +*1024*1024*1024) from test; +INSERT 0 128 +postgres=3D# insert into test (val) select round(random()=20 +*1024*1024*1024) from test; +INSERT 0 256 +postgres=3D# insert into test (val) select round(random()=20 +*1024*1024*1024) from test; +INSERT 0 512 +postgres=3D# vacuum full analyze; +VACUUM +postgres=3D# explain select count(*) from (select distinct on (val) * =20= + +from test) as foo; + QUERY PLAN +------------------------------------------------------------------------=20= + +------------ +Aggregate (cost=3D55.63..55.64 rows=3D1 width=3D0) + -> Unique (cost=3D0.00..42.82 rows=3D1024 width=3D8) + -> Index Scan using testval on test (cost=3D0.00..40.26 =20 +rows=3D1024 width=3D8) +(3 rows) + +postgres=3D# select count(1) from test; +count +------- + 1024 +(1 row) + +postgres=3D# set enable_indexscan=3Doff; +SET +postgres=3D# explain select count(*) from (select distinct on (val) * =20= + +from test) as foo; + QUERY PLAN +------------------------------------------------------------------------=20= + +-- +Aggregate (cost=3D85.36..85.37 rows=3D1 width=3D0) + -> Unique (cost=3D67.44..72.56 rows=3D1024 width=3D8) + -> Sort (cost=3D67.44..70.00 rows=3D1024 width=3D8) + Sort Key: test.val + -> Seq Scan on test (cost=3D0.00..16.24 rows=3D1024 =20= + +width=3D8) +(5 rows) + +postgres=3D# set enable_indexscan=3Don; +SET +postgres=3D# insert into test (val) select round(random()=20 +*1024*1024*1024) from test; +INSERT 0 1024 +postgres=3D# vacuum full analyze; +VACUUM +postgres=3D# explain select count(*) from (select distinct on (val) * =20= + +from test) as foo; + QUERY PLAN +------------------------------------------------------------------------=20= + +------------ +Aggregate (cost=3D105.25..105.26 rows=3D1 width=3D0) + -> Unique (cost=3D0.00..79.65 rows=3D2048 width=3D8) + -> Index Scan using testval on test (cost=3D0.00..74.53 =20 +rows=3D2048 width=3D8) +(3 rows) + +postgres=3D# + + + + +From pgsql-performance-owner@postgresql.org Thu Nov 24 22:37:52 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0BC1EDBCC6 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Thu, 24 Nov 2005 22:37:52 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 79409-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 02:37:55 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 67F61DB839 + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 22:37:49 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAP2brcw017381; + Thu, 24 Nov 2005 21:37:53 -0500 (EST) +To: Pailloncy Jean-Gerard <jg@rilk.com> +cc: pgsql-performance@postgresql.org +Subject: Re: 8.1 count(*) distinct: IndexScan/SeqScan +In-reply-to: <A6F55E12-4479-49F6-B3EE-8CFCC8541179@rilk.com> +References: <334D9941-B5B3-4D18-8312-F85D0FB054ED@rilk.com> + <A6F55E12-4479-49F6-B3EE-8CFCC8541179@rilk.com> +Comments: In-reply-to Pailloncy Jean-Gerard <jg@rilk.com> + message dated "Fri, 25 Nov 2005 00:34:16 +0100" +Date: Thu, 24 Nov 2005 21:37:53 -0500 +Message-ID: <17380.1132886273@sss.pgh.pa.us> +From: Tom Lane <tgl@sss.pgh.pa.us> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.004 required=5 tests=[AWL=0.004] +X-Spam-Score: 0.004 +X-Spam-Level: +X-Archive-Number: 200511/506 +X-Sequence-Number: 15763 + +Pailloncy Jean-Gerard <jg@rilk.com> writes: +> I redo the test, with a freshly installed data directory. Same result. + +What "same result"? You only ran it up to 2K rows, not 2M. In any +case, EXPLAIN without ANALYZE is pretty poor ammunition for complaining +that the planner made the wrong choice. I ran the same test case, +and AFAICS the indexscan is the right choice at 2K rows: + +regression=# explain analyze select count(*) from (select distinct on (val) * from test) as foo; + QUERY PLAN +---------------------------------------------------------------------------------------------------------------------------------- + Aggregate (cost=105.24..105.25 rows=1 width=0) (actual time=41.561..41.565 rows=1 loops=1) + -> Unique (cost=0.00..79.63 rows=2048 width=8) (actual time=0.059..32.459 rows=2048 loops=1) + -> Index Scan using testval on test (cost=0.00..74.51 rows=2048 width=8) (actual time=0.049..13.197 rows=2048 loops=1) + Total runtime: 41.683 ms +(4 rows) + +regression=# set enable_indexscan TO 0; +SET +regression=# explain analyze select count(*) from (select distinct on (val) * from test) as foo; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------------- + Aggregate (cost=179.96..179.97 rows=1 width=0) (actual time=59.567..59.571 rows=1 loops=1) + -> Unique (cost=144.12..154.36 rows=2048 width=8) (actual time=21.438..50.434 rows=2048 loops=1) + -> Sort (cost=144.12..149.24 rows=2048 width=8) (actual time=21.425..30.589 rows=2048 loops=1) + Sort Key: test.val + -> Seq Scan on test (cost=0.00..31.48 rows=2048 width=8) (actual time=0.014..9.902 rows=2048 loops=1) + Total runtime: 60.265 ms +(6 rows) + + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 25 00:21:00 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 1F51DDBD91 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 00:20:59 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 19676-02-2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 04:20:56 +0000 (GMT) +X-Greylist: delayed 01:05:44.879458 by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by svr1.postgresql.org (Postfix) with ESMTP id 3AF93DBCA4 + for <pgsql-performance@postgresql.org>; + Fri, 25 Nov 2005 00:20:55 -0400 (AST) +Received: from pillage.dreamhost.com (pillage.dreamhost.com [66.33.213.23]) + by svr2.postgresql.org (Postfix) with ESMTP id 30752F0B00 + for <pgsql-performance@postgresql.org>; + Fri, 25 Nov 2005 03:15:17 +0000 (GMT) +Received: from [127.0.0.1] (ip-66-33-217-47.dreamhost.com [66.33.217.47]) + by pillage.dreamhost.com (Postfix) with ESMTP id B5B46BE8C + for <pgsql-performance@postgresql.org>; + Thu, 24 Nov 2005 19:15:12 -0800 (PST) +Message-ID: <438681E0.6070006@kylecordes.com> +Date: Thu, 24 Nov 2005 21:15:44 -0600 +From: Kyle Cordes <kyle@kylecordes.com> +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: 8.1 count(*) distinct: IndexScan/SeqScan +References: <334D9941-B5B3-4D18-8312-F85D0FB054ED@rilk.com> + <A6F55E12-4479-49F6-B3EE-8CFCC8541179@rilk.com> + <17380.1132886273@sss.pgh.pa.us> +In-Reply-To: <17380.1132886273@sss.pgh.pa.us> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/507 +X-Sequence-Number: 15764 + +Tom Lane wrote: + +>What "same result"? You only ran it up to 2K rows, not 2M. In any +>case, EXPLAIN without ANALYZE is pretty poor ammunition for complaining +>that the planner made the wrong choice. I ran the same +> + +Hello, sorry to jump in mid-stream, but this reminded me of something. + +I have hit cases where I have a query for which there is a somewhat +"obvious" (to a human...) query plan that should make it possible to get +a query answer pretty quickly. Yet the query "never" finishes (or +rather, after hours of waiting I finally kill it). I assume this is +because of a sub-optimal query plan. But, it appears that an EXPLAIN +ANALYZE runs the actual query, so it takes as long as the actual query. + +In such a case, how can I go about tracking down the issue, up to an +including a complaint about the query planner? :-) + +(Overall, I'm pretty pleased with the PG query planner; it often gets +better results than another, popular commercial DBMS we use here.... +that is just a general impression, not the result of setting up the same +schema in each for a comparison.) + +Kyle Cordes +www.kylecordes.com + + + +From pgsql-performance-owner@postgresql.org Fri Nov 25 00:50:07 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A797AD9582 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 00:50:06 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 29647-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 04:50:04 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from travis.trilogy.com (unknown [149.75.65.93]) + by svr1.postgresql.org (Postfix) with ESMTP id E936CD859B + for <pgsql-performance@postgresql.org>; + Fri, 25 Nov 2005 00:50:03 -0400 (AST) +To: Tom Lane <tgl@sss.pgh.pa.us> +Cc: pgsql-performance@postgresql.org +Subject: Re: xlog flush request error +MIME-Version: 1.0 +X-Mailer: Lotus Notes Release 5.0.9 November 16, 2001 +Message-ID: <OF216BE6EA.7FF65954-ON862570C4.001A3FC6@trilogy.com> +From: Vipul.Gupta@trilogy.com +Date: Thu, 24 Nov 2005 22:48:17 -0600 +X-MIMETrack: Serialize by Router on Travis/Trilogy(Release 5.0.12 |February + 13, + 2003) at 11/24/2005 10:48:22 PM, + Serialize complete at 11/24/2005 10:48:22 PM +Content-Type: multipart/alternative; + boundary="=_alternative 001A79C8652570C4_=" +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.551 required=5 tests=[HTML_MESSAGE=0.001, + NO_REAL_NAME=0.55] +X-Spam-Score: 0.551 +X-Spam-Level: +X-Archive-Number: 200511/508 +X-Sequence-Number: 15765 + +This is a multipart message in MIME format. +--=_alternative 001A79C8652570C4_= +Content-Type: text/plain; charset="us-ascii" + +Hi tom, + +basically when i run any query with database say, + +select count(*) from table1; + +It gives me the following error trace: +WARNING: could not write block 297776 of 1663/2110743/2110807 +DETAIL: Multiple failures --- write error may be permanent. +ERROR: xlog flush request 7/7D02338C is not satisfied --- flushed only to +3/2471E324 + writing block 297776 of relation 1663/2110743/2110807 +xlog flush request 7/7D02338C is not satisfied --- flushed only to +3/2471E324 +xlog flush request 7/7D02338C is not satisfied --- flushed only to +3/2471E324\q + +i tried using pg_resetxlog but till date, have not been able to solve this +problem + +Regards, +Vipul Gupta + + + + + +Tom Lane <tgl@sss.pgh.pa.us> +11/24/2005 09:07 PM + + + To: Vipul.Gupta@trilogy.com + cc: pgsql-performance@postgresql.org + Subject: Re: [PERFORM] xlog flush request error + + +Vipul.Gupta@trilogy.com writes: +> Can anyone suggest how do i fix this + +> xlog flush request 7/7D02338C is not satisfied --- flushed only to +> 3/2471E324 + +This looks like corrupt data to me --- specifically, garbage in the LSN +field of a page header. Is that all you get? PG 7.4 and up should tell +you the problem page number in a CONTEXT: line. + + regards, tom lane + + + + +--=_alternative 001A79C8652570C4_= +Content-Type: text/html; charset="us-ascii" + + +<br><font size=2 face="sans-serif">Hi tom,</font> +<br> +<br><font size=2 face="sans-serif">basically when i run any query with database say,</font> +<br> +<br><font size=2 face="sans-serif">select count(*) from table1;</font> +<br> +<br><font size=2 face="sans-serif">It gives me the following error trace: </font> +<br><font size=2 face="sans-serif">WARNING:  could not write block 297776 of 1663/2110743/2110807</font> +<br><font size=2 face="sans-serif">DETAIL:  Multiple failures --- write error may be permanent.</font> +<br><font size=2 face="sans-serif">ERROR:  xlog flush request 7/7D02338C is not satisfied --- flushed only to 3/2471E324</font> +<br><font size=2 face="sans-serif"> writing block 297776 of relation 1663/2110743/2110807</font> +<br><font size=2 face="sans-serif">xlog flush request 7/7D02338C is not satisfied --- flushed only to 3/2471E324</font> +<br><font size=2 face="sans-serif">xlog flush request 7/7D02338C is not satisfied --- flushed only to 3/2471E324\q</font> +<br> +<br><font size=2 face="sans-serif">i tried using pg_resetxlog but till date, have not been able to solve this problem </font> +<br> +<br><font size=2 face="sans-serif">Regards,</font> +<br><font size=2 face="sans-serif">Vipul Gupta<br> +</font> +<br> +<br> +<br> +<table width=100%> +<tr valign=top> +<td> +<td><font size=1 face="sans-serif"><b>Tom Lane <tgl@sss.pgh.pa.us></b></font> +<p><font size=1 face="sans-serif">11/24/2005 09:07 PM</font> +<br> +<td><font size=1 face="Arial">        </font> +<br><font size=1 face="sans-serif">        To:        Vipul.Gupta@trilogy.com</font> +<br><font size=1 face="sans-serif">        cc:        pgsql-performance@postgresql.org</font> +<br><font size=1 face="sans-serif">        Subject:        Re: [PERFORM] xlog flush request error</font></table> +<br> +<br> +<br><font size=2 face="Courier New">Vipul.Gupta@trilogy.com writes:<br> +> Can anyone suggest how do i fix this<br> +<br> +>  xlog flush request 7/7D02338C is not satisfied --- flushed only to <br> +> 3/2471E324<br> +<br> +This looks like corrupt data to me --- specifically, garbage in the LSN<br> +field of a page header.  Is that all you get?  PG 7.4 and up should tell<br> +you the problem page number in a CONTEXT: line.<br> +<br> +                                                   regards, tom lane<br> +<br> +</font> +<br> +<br> +--=_alternative 001A79C8652570C4_=-- + +From pgsql-performance-owner@postgresql.org Fri Nov 25 00:59:33 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id DF456DA206 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 00:59:31 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 28155-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 04:59:28 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by svr1.postgresql.org (Postfix) with ESMTP id 4E2ADD9C61 + for <pgsql-performance@postgresql.org>; + Fri, 25 Nov 2005 00:59:26 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAP4xQdc018822; + Thu, 24 Nov 2005 23:59:26 -0500 (EST) +To: Vipul.Gupta@trilogy.com +cc: pgsql-performance@postgresql.org +Subject: Re: xlog flush request error +In-reply-to: <OF216BE6EA.7FF65954-ON862570C4.001A3FC6@trilogy.com> +References: <OF216BE6EA.7FF65954-ON862570C4.001A3FC6@trilogy.com> +Comments: In-reply-to Vipul.Gupta@trilogy.com + message dated "Thu, 24 Nov 2005 22:48:17 -0600" +Date: Thu, 24 Nov 2005 23:59:26 -0500 +Message-ID: <18821.1132894766@sss.pgh.pa.us> +From: Tom Lane <tgl@sss.pgh.pa.us> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.004 required=5 tests=[AWL=0.004] +X-Spam-Score: 0.004 +X-Spam-Level: +X-Archive-Number: 200511/509 +X-Sequence-Number: 15766 + +Vipul.Gupta@trilogy.com writes: +> ERROR: xlog flush request 7/7D02338C is not satisfied --- flushed only to +> 3/2471E324 +> writing block 297776 of relation 1663/2110743/2110807 + +You need to fix or zero out that data block ... + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Fri Nov 25 07:40:50 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id EBFF6D6ED8 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 07:40:49 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 82999-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 11:40:51 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from cassarossa.samfundet.no (cassarossa.samfundet.no + [129.241.93.19]) + by svr1.postgresql.org (Postfix) with ESMTP id 1E872D78B6 + for <pgsql-performance@postgresql.org>; + Fri, 25 Nov 2005 07:40:45 -0400 (AST) +Received: from trofast.sesse.net ([129.241.93.32]) + by cassarossa.samfundet.no with esmtp (Exim 4.50) id 1Efbwc-0007Km-3Z + for pgsql-performance@postgresql.org; Fri, 25 Nov 2005 12:40:47 +0100 +Received: from sesse by trofast.sesse.net with local (Exim 3.36 #1 (Debian)) + id 1Efbw9-0002mz-00 + for <pgsql-performance@postgresql.org>; Fri, 25 Nov 2005 12:40:17 +0100 +Date: Fri, 25 Nov 2005 12:40:17 +0100 +From: "Steinar H. Gunderson" <sgunderson@bigfoot.com> +To: pgsql-performance@postgresql.org +Subject: Re: 8.1 count(*) distinct: IndexScan/SeqScan +Message-ID: <20051125114017.GA10575@uio.no> +Mail-Followup-To: pgsql-performance@postgresql.org +References: <334D9941-B5B3-4D18-8312-F85D0FB054ED@rilk.com> + <A6F55E12-4479-49F6-B3EE-8CFCC8541179@rilk.com> + <17380.1132886273@sss.pgh.pa.us> <438681E0.6070006@kylecordes.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=utf-8 +Content-Disposition: inline +In-Reply-To: <438681E0.6070006@kylecordes.com> +X-Operating-System: Linux 2.6.14 on a i686 +X-Message-Flag: Outlook? --> http://www.mozilla.org/products/thunderbird/ +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/510 +X-Sequence-Number: 15767 + +On Thu, Nov 24, 2005 at 09:15:44PM -0600, Kyle Cordes wrote: +> I have hit cases where I have a query for which there is a somewhat +> "obvious" (to a human...) query plan that should make it possible to get +> a query answer pretty quickly. Yet the query "never" finishes (or +> rather, after hours of waiting I finally kill it). I assume this is +> because of a sub-optimal query plan. But, it appears that an EXPLAIN +> ANALYZE runs the actual query, so it takes as long as the actual query. + +In this case, you probably can't do better than EXPLAIN. Look at the +estimates, find out if the cost is way high somewhere. If a simple query +estimates a billion disk page fetches, something is probably wrong, ie. the +planner did for some reason overlook the query plan you were thinking of. (A +common problem here used to include data type mismatches leading to less +efficient joins, lack of index scans and less efficient IN/NOT IN; most of +that is fixed, but a few cases still remain.) + +If the query is estimated at a reasonable amount of disk page fetches but +still takes forever, look at the number of estimated rows returned. Do they +make sense? If you run subsets of your query, are they about right? If not, +you probably want to fiddle with the statistics targets. + +/* Steinar */ +-- +Homepage: http://www.sesse.net/ + +From pgsql-performance-owner@postgresql.org Fri Nov 25 08:31:50 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id A1B58D7281 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 08:31:49 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 88048-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 12:31:51 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mx2.surnet.cl (mx2.surnet.cl [216.155.73.181]) + by svr1.postgresql.org (Postfix) with ESMTP id A8843D721C + for <pgsql-performance@postgresql.org>; + Fri, 25 Nov 2005 08:31:46 -0400 (AST) +Received: from unknown (HELO cluster.surnet.cl) ([216.155.73.165]) + by mx2.surnet.cl with ESMTP; 25 Nov 2005 09:32:41 -0300 +Received: from alvh.no-ip.org (200.85.218.89) by cluster.surnet.cl (7.0.043) + (authenticated as alvherre@surnet.cl) + id 43501597005A0448 for pgsql-performance@postgresql.org; + Fri, 25 Nov 2005 09:31:49 -0300 +Received: by alvh.no-ip.org (Postfix, from userid 1000) + id C5E33C30B0D; Fri, 25 Nov 2005 09:32:00 -0300 (CLST) +Date: Fri, 25 Nov 2005 09:32:00 -0300 +From: Alvaro Herrera <alvherre@commandprompt.com> +To: pgsql-performance@postgresql.org +Subject: Re: 8.1 count(*) distinct: IndexScan/SeqScan +Message-ID: <20051125123200.GD14707@surnet.cl> +Mail-Followup-To: pgsql-performance@postgresql.org +References: <334D9941-B5B3-4D18-8312-F85D0FB054ED@rilk.com> + <A6F55E12-4479-49F6-B3EE-8CFCC8541179@rilk.com> + <17380.1132886273@sss.pgh.pa.us> <438681E0.6070006@kylecordes.com> + <20051125114017.GA10575@uio.no> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <20051125114017.GA10575@uio.no> +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=3.487 required=5 tests=[AWL=-0.582, + DNS_FROM_RFC_ABUSE=0.479, DNS_FROM_RFC_POST=1.44, + RCVD_IN_NJABL_PROXY=0.327, RCVD_IN_SORBS_SOCKS=1.823] +X-Spam-Score: 3.487 +X-Spam-Level: *** +X-Archive-Number: 200511/511 +X-Sequence-Number: 15768 + +Steinar H. Gunderson wrote: +> On Thu, Nov 24, 2005 at 09:15:44PM -0600, Kyle Cordes wrote: +> > I have hit cases where I have a query for which there is a somewhat +> > "obvious" (to a human...) query plan that should make it possible to get +> > a query answer pretty quickly. Yet the query "never" finishes (or +> > rather, after hours of waiting I finally kill it). I assume this is +> > because of a sub-optimal query plan. But, it appears that an EXPLAIN +> > ANALYZE runs the actual query, so it takes as long as the actual query. +> +> In this case, you probably can't do better than EXPLAIN. Look at the +> estimates, find out if the cost is way high somewhere. + +Also you want to make absolutely sure all the involved tables have been +ANALYZEd recently. + +If you have weird cases where there is an obvious query plan and the +optimizer is not using it, by all means submit it so that developers can +take a look at how to improve the optimizer. + +-- +Alvaro Herrera http://www.CommandPrompt.com/ +The PostgreSQL Company - Command Prompt, Inc. + +From pgsql-performance-owner@postgresql.org Fri Nov 25 10:47:33 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id D8106DBD8C + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 10:47:31 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 20737-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 14:47:34 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.rilk.com (mail.rilk.com [193.19.217.130]) + by svr1.postgresql.org (Postfix) with ESMTP id A57DEDBD8B + for <pgsql-performance@postgresql.org>; + Fri, 25 Nov 2005 10:47:28 -0400 (AST) +Received: from [192.168.0.1] (cev75-1-81-57-249-136.fbx.proxad.net + [81.57.249.136]) (authenticated bits=0) + by mail.rilk.com (8.13.0/8.13.0) with ESMTP id jAPElIwn012874 + (version=TLSv1/SSLv3 cipher=EDH-DSS-DES-CBC3-SHA bits=168 verify=NO) + for <pgsql-performance@postgresql.org>; + Fri, 25 Nov 2005 15:47:32 +0100 (CET) +Mime-Version: 1.0 (Apple Message framework v746.2) +In-Reply-To: <17380.1132886273@sss.pgh.pa.us> +References: <334D9941-B5B3-4D18-8312-F85D0FB054ED@rilk.com> + <A6F55E12-4479-49F6-B3EE-8CFCC8541179@rilk.com> + <17380.1132886273@sss.pgh.pa.us> +Content-Type: text/plain; charset=ISO-8859-1; delsp=yes; format=flowed +Message-Id: <78D03263-E40B-4E49-964C-D8013225247F@rilk.com> +Content-Transfer-Encoding: quoted-printable +From: Pailloncy Jean-Gerard <jg@rilk.com> +Subject: Re: 8.1 count(*) distinct: IndexScan/SeqScan +Date: Fri, 25 Nov 2005 15:47:16 +0100 +To: pgsql-performance@postgresql.org +X-Mailer: Apple Mail (2.746.2) +X-DCC-CTc-dcc2-Metrics: mail.rilk.com 1031; Body=1 Fuz1=1 Fuz2=1 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/512 +X-Sequence-Number: 15769 + +> What "same result"? You only ran it up to 2K rows, not 2M. In any +Sorry, I do this over and over until xxx.000 rows but I do not write =20 +in the mail. + +I do it again. initdb, create table, insert, vacuum full analyze, =20 +explain analyze at each stage. +And there was no problem. + +So I make a copy of the offending data directory, and try again. And =20 +I got IndexScan only. +I will get an headheak ;-) + +Too big to be send by mail: http://rilk.com/pg81.html + +Cordialement, +Jean-G=E9rard Pailloncy + + +From pgsql-performance-owner@postgresql.org Fri Nov 25 15:36:40 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 06C01DBDF9 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 15:36:40 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 73941-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 19:36:38 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.192]) + by svr1.postgresql.org (Postfix) with ESMTP id 97137DBDF8 + for <pgsql-performance@postgresql.org>; + Fri, 25 Nov 2005 15:36:35 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id 55so714650wri + for <pgsql-performance@postgresql.org>; + Fri, 25 Nov 2005 11:36:36 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; + b=Y4ngQ8e4GRwETACod41hWBFRmXd2/Lbc6yVcPSCQYweagTH86PRjucJTu6Do68ky55uBF1n3TJ7oTw26Z3LLGop+4yurxDY+oTFza34EqZI7fY2QiYUdpJeCm1NTAz7obqE6pOP0AwzqUXvk/bt6C2sA081cNiD0nX5QkXgOGrw= +Received: by 10.65.137.14 with SMTP id p14mr8966872qbn; + Fri, 25 Nov 2005 11:36:36 -0800 (PST) +Received: by 10.65.177.1 with HTTP; Fri, 25 Nov 2005 11:36:35 -0800 (PST) +Message-ID: <3cf983d0511251136j1afa0ec4i9a3987d250befe47@mail.gmail.com> +Date: Fri, 25 Nov 2005 19:36:35 +0000 +From: Rodrigo Madera <rodrigo.madera@gmail.com> +To: pgsql-performance@postgresql.org +Subject: Newbie question: ultra fast count(*) +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/513 +X-Sequence-Number: 15770 + +I have been reading all this technical talk about costs and such that +I don't (_yet_) understand. + +Now I'm scared... what's the fastest way to do an equivalent of +count(*) on a table to know how many items it has? + +Thanks, +Rodrigo + +From pgsql-performance-owner@postgresql.org Fri Nov 25 15:40:11 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 19FB4D7F97 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 15:40:10 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 76037-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Fri, 25 Nov 2005 19:40:09 +0000 (GMT) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from xproxy.gmail.com (xproxy.gmail.com [66.249.82.202]) + by svr1.postgresql.org (Postfix) with ESMTP id 63AB5D6FE3 + for <pgsql-performance@postgresql.org>; + Fri, 25 Nov 2005 15:40:05 -0400 (AST) +Received: by xproxy.gmail.com with SMTP id s19so1565452wxc + for <pgsql-performance@postgresql.org>; + Fri, 25 Nov 2005 11:40:06 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; + b=SWqUATreWpkUqOlNonwH4bX2BtsD7rmaX6V6RW7YnYPAz3ST5YMsfFcIFRSitdJ4j71XGdpWojiku4gYk3PT8DxsYkr8O6jSQu4xyc0VXZmgomcGRGIO+FnJ11CEWLr1AfXi2yruFXKOcK66f+PadaW821tbE8Rlaa/4UpNSCjI= +Received: by 10.65.206.3 with SMTP id i3mr8690384qbq; + Fri, 25 Nov 2005 11:40:06 -0800 (PST) +Received: by 10.65.180.14 with HTTP; Fri, 25 Nov 2005 11:40:06 -0800 (PST) +Message-ID: <c2d9e70e0511251140x5f2a6c2ah6fc81d88fcfb2213@mail.gmail.com> +Date: Fri, 25 Nov 2005 14:40:06 -0500 +From: Jaime Casanova <systemguards@gmail.com> +To: Rodrigo Madera <rodrigo.madera@gmail.com> +Subject: Re: Newbie question: ultra fast count(*) +Cc: pgsql-performance@postgresql.org +In-Reply-To: <3cf983d0511251136j1afa0ec4i9a3987d250befe47@mail.gmail.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable +Content-Disposition: inline +References: <3cf983d0511251136j1afa0ec4i9a3987d250befe47@mail.gmail.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.364 required=5 tests=[AWL=0.364] +X-Spam-Score: 0.364 +X-Spam-Level: +X-Archive-Number: 200511/514 +X-Sequence-Number: 15771 + +On 11/25/05, Rodrigo Madera <rodrigo.madera@gmail.com> wrote: +> I have been reading all this technical talk about costs and such that +> I don't (_yet_) understand. +> +> Now I'm scared... what's the fastest way to do an equivalent of +> count(*) on a table to know how many items it has? +> +> Thanks, +> Rodrigo +> + +you really *need* this? + +you can do +SELECT reltuples FROM pg_class WHERE relname =3D 'your_table_name'; + +but this will give you an estimate... if you want real values you can +make a TRIGGER that maintain a counter in another table + +-- +regards, +Jaime Casanova +(DBA: DataBase Aniquilator ;) + +From pgsql-performance-owner@postgresql.org Sun Nov 27 00:40:29 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 0F265DA7E2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 00:40:29 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 72345-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 04:40:27 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.invendra.net (sbx-01.invendra.net [66.139.76.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 7056DD778E + for <pgsql-performance@postgresql.org>; + Sun, 27 Nov 2005 00:40:22 -0400 (AST) +Received: from david.lang.hm (dsl081-044-215.lax1.dsl.speakeasy.net + [64.81.44.215]) + by mail.invendra.net (Postfix) with ESMTP id 6E43A1AC3E9 + for <pgsql-performance@postgresql.org>; + Sat, 26 Nov 2005 17:36:57 -0800 (PST) +Date: Sat, 26 Nov 2005 06:28:50 -0800 (PST) +From: David Lang <dlang@invendra.net> +X-X-Sender: dlang@david.lang.hm +To: pgsql-performance@postgresql.org +Subject: Re: Open request for benchmarking input +Message-ID: <Pine.LNX.4.62.0511260608030.2790@qnivq.ynat.uz> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.746 required=5 tests=[DATE_IN_PAST_06_12=0.746] +X-Spam-Score: 0.746 +X-Spam-Level: +X-Archive-Number: 200511/520 +X-Sequence-Number: 15777 + +Ok, I've subscribed (hopefully list volume won't kill me :-) + +I'm covering several things in this message since I didn't receive the +prior messages in the thread + +first off these benchamrks are not being sponsered by my employer, they +need the machines burned in and so I'm going to use them for the tests +while burning them in. I can spend a little official time on this, +justifying it as learning the proper config/tuneing settings for our +project, but not too much. and I'm deliberatly not useing my work e-mail +and am not mentioning the company name, so please respect this and keep +the two seperate (some of you have dealt with us formally, others will +over the next few months) + +this means no remote access for people (but I am willing to run tests and +send configs around). in fact the machines will not have Internet access +for the duration of the tests. + +it also means I'm doing almost all the configuration work for this on my +own time (nights and weekends). the machines will not be moved to +production for a couple of months. this should mean that we can go back +and forth with questions and answers (albeit somewhat slowly, with me +checking in every night) while whatever tests are done happen during the +day. once we get past the system tuneing and start doing different tests +it would probably be helpful if people can send me scripts to run that I +can just let loose. + +I don't have any money to pay for benchmark suites, so if things like the +TPC benchmarks cost money to do I won't be able to do them + +to clarify the hardware + +I have 5 machines total to work with, this includes client machines to +make the queries (I may be able to get hold of 2-3 more, but they are +similar configs) + +none of these have dual-core processors on them, the CPU's are 246 or 252 +Opterons (I'll have to double check which is in which machine, I think the +large disk machine has 246's and the others 252's) + +I have access to a gig-E switch that's on a fairly idle network to use to +connect these machines + +the large-disk machine has 3ware 9500 series 8-port SATA controllers in +them with battery backup. in our official dealings with Greenplum we +attempted to do a set of benchmarks on that machine, but had horrible +timing with me being too busy when they worked with us on this and we +never did figure out the best setting to use for this machine. + +Part of the reason I posted this to /. rather then just contacting you and +MySQL folks directly is that I would like to see a reasonable set of +benchmarks agreed to and have people with different hardware then I have +run the same sets of tests. I know the tuneing will be different for +different hardware, but if we can have a bunch of people run similar tests +we should learn a lot. + +David Lang + +From pgsql-performance-owner@postgresql.org Sun Nov 27 01:47:11 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 05870D9DA2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 01:47:11 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 77422-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 05:47:09 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.invendra.net (sbx-01.invendra.net [66.139.76.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 63264D8DAF + for <pgsql-performance@postgresql.org>; + Sun, 27 Nov 2005 01:47:08 -0400 (AST) +Received: from david.lang.hm (dsl081-044-215.lax1.dsl.speakeasy.net + [64.81.44.215]) + by mail.invendra.net (Postfix) with ESMTP id DF9B11AC3EA + for <pgsql-performance@postgresql.org>; + Sat, 26 Nov 2005 19:08:39 -0800 (PST) +Date: Sat, 26 Nov 2005 08:00:33 -0800 (PST) +From: David Lang <dlang@invendra.net> +X-X-Sender: dlang@david.lang.hm +To: pgsql-performance@postgresql.org +Subject: Open request for benchmarking input +Message-ID: <Pine.LNX.4.62.0511260745370.2790@qnivq.ynat.uz> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.746 required=5 tests=[DATE_IN_PAST_06_12=0.746] +X-Spam-Score: 0.746 +X-Spam-Level: +X-Archive-Number: 200511/522 +X-Sequence-Number: 15779 + +>These boxes don't look like being designed for a DB server. The first are +>very CPU bound, and the third may be a good choice for very large amounts +>of streamed data, but not optimal for TP random access. + +I don't know what you mean when you say that the first ones are CPU bound, +they have far more CPU then they do disk I/O + +however I will agree that they were not designed to be DB servers, they +weren't. they happen to be the machines that I have available. + +they only have a pair of disks each, which would not be reasonable for +most production DB uses, and they have far more CPU then is normally +reccomended. So I'll have to run raid 0 instead of 0+1 (or not use raid) +which would be unacceptable in a production environment, but can still +give some useful info. + +the 5th box _was_ purchased to be a DB server, but one to store and +analyse large amounts of log data, so large amounts of data storage were +more important then raw DB performance (although we did max out the RAM at +16G to try and make up for it). it was a deliberate price/performance +tradeoff. this machine ran ~$20k, but a similar capacity with SCSI drives +would have been FAR more expensive (IIRC a multiple of 4x or more more +expensive). + +>Hopefully, when publicly visible benchmarks are performed, machines are +>used that comply with common engineering knowledge, ignoring those guys +>who still believe that sequential performance is the most important issue +>on disk subsystems for DBMS. + +are you saying that I shouldn't do any benchmarks becouse the machines +aren't what you would consider good enough? + +if so I disagree with you and think that benchmarks should be done on even +worse machines, but should also be done on better machines. (are you +volunteering to provide time on better machines for benchmarks?) + +not everyone will buy a lot of high-end hardware before they start useing +a database. in fact most companies will start with a database on lower end +hardware and then as their requirements grow they will move to better +hardware. I'm willing to bet that what I have available is better then the +starting point for most places. + +Postgres needs to work on the low end stuff as well as the high end stuff +or people will write their app to work with things that DO run on low end +hardware and they spend much more money then is needed to scale the +hardware up rather then re-writing their app. + +Part of the reason that I made the post on /. to start this was the hope +that a reasonable set of benchmarks could be hammered out and then more +people then just me could run them to get a wider range of results. + +David Lang + +From pgsql-performance-owner@postgresql.org Sun Nov 27 00:40:30 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8CA5BDA924 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 00:40:29 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 72048-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 04:40:27 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.invendra.net (sbx-01.invendra.net [66.139.76.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 750B5DA537 + for <pgsql-performance@postgresql.org>; + Sun, 27 Nov 2005 00:40:22 -0400 (AST) +Received: from david.lang.hm (dsl081-044-215.lax1.dsl.speakeasy.net + [64.81.44.215]) + by mail.invendra.net (Postfix) with ESMTP id 3BBE21AC3EB + for <pgsql-performance@postgresql.org>; + Sat, 26 Nov 2005 19:21:51 -0800 (PST) +Date: Sat, 26 Nov 2005 08:13:40 -0800 (PST) +From: David Lang <dlang@invendra.net> +X-X-Sender: dlang@david.lang.hm +To: pgsql-performance@postgresql.org +Subject: Re: Open request for benchmarking input +Message-ID: <Pine.LNX.4.62.0511260812460.2790@qnivq.ynat.uz> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.746 required=5 tests=[DATE_IN_PAST_06_12=0.746] +X-Spam-Score: 0.746 +X-Spam-Level: +X-Archive-Number: 200511/521 +X-Sequence-Number: 15778 + +by the way, this is the discussion that promped me to start this project +http://lwn.net/Articles/161323/ + +David Lang + +From pgsql-performance-owner@postgresql.org Sat Nov 26 14:28:55 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 7091BDBDCB + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 26 Nov 2005 14:28:54 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 74544-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 26 Nov 2005 18:28:52 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtp112.sbc.mail.mud.yahoo.com (smtp112.sbc.mail.mud.yahoo.com + [68.142.198.211]) + by svr1.postgresql.org (Postfix) with SMTP id 254C4DBDA4 + for <pgsql-performance@postgresql.org>; + Sat, 26 Nov 2005 14:28:49 -0400 (AST) +Received: (qmail 91055 invoked from network); 26 Nov 2005 18:28:46 -0000 +Received: from unknown (HELO discord.dyndns.org) + (jeffroe996@sbcglobal.net@69.227.55.89 with plain) + by smtp112.sbc.mail.mud.yahoo.com with SMTP; 26 Nov 2005 18:28:45 -0000 +Received: from localhost (localhost.localdomain [127.0.0.1]) + by discord.dyndns.org (8.13.4/8.13.4) with ESMTP id jAQISbL4006064 + for <pgsql-performance@postgresql.org>; Sat, 26 Nov 2005 10:28:39 -0800 +Date: Sat, 26 Nov 2005 10:28:36 -0800 (PST) +From: Jeff Frost <jeff@frostconsultingllc.com> +X-X-Sender: jeff@discord.dyndns.org +To: pgsql-performance@postgresql.org +Subject: Open request for benchmarking input +Message-ID: <Pine.LNX.4.64.0511261025140.16022@discord.dyndns.org> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.028 required=5 tests=[AWL=0.028] +X-Spam-Score: 0.028 +X-Spam-Level: +X-Archive-Number: 200511/515 +X-Sequence-Number: 15772 + +Did you folks see this article on Slashdot with a fellow requesting input on +what sort of benchmarks to run to get a good Postgresql vs Mysql dataset? +Perhaps this would be a good opportunity for us to get some good benchmarking +done. Here's the article link and top text: + +http://ask.slashdot.org/article.pl?sid=05/11/26/0317213 + + David Lang asks: "With the release of MySQL 5.0, PostgreSQL 8.1, and the flap +over Oracle purchasing InnoDB, the age old question of performance is coming +up again. I've got some boxes that were purchased for a data warehouse project +that isn't going to be installed for a month or two, and could probably +squeeze some time in to do some benchmarks on the machines. However, the +question is: what should be done that's reasonably fair to both MySQL and +PostgreSQL? We all know that careful selection of the benchmark can seriously +skew the results, and I want to avoid that (in fact I would consider it close +to ideal if the results came out that each database won in some tests). I +would also not like to spend time generating the benchmarks only to have the +losing side accuse me of being unfair. So, for both MySQL and PostgreSQL +advocates, what would you like to see in a series of benchmarks?" + + "The hardware I have available is as follows: + + * 2x dual Opteron 8G ram, 2x144G 15Krpm SCSI + * 2x dual Opteron 8G ram, 2x72G 15Krpm SCSI + * 1x dual Opteron 16G ram, 2x36G 15Krpm SCSI 16x400G 7200rpm SATA + +I would prefer to use Debian Sarge as the base install of the systems (with +custom built kernels), but would compile the databases from source rather then +using binary packages. + +For my own interests, I would like to at least cover the following bases: 32 +bit vs 64 bit vs 64 bit kernel + 32 bit user-space; data warehouse type tests +(data >> memory); and web prefs test (active data RAM) + +What specific benchmarks should be run, and what other things should be +tested? Where should I go for assistance on tuning each database, evaluating +the benchmark results, and re-tuning them?" + +--- +Jeff Frost, Owner +<jeff@frostconsultingllc.com> +Frost Consulting, LLC http://www.frostconsultingllc.com/ +Phone: 650-780-7908 FAX: 650-649-1954 + +From pgsql-performance-owner@postgresql.org Sun Nov 27 01:59:09 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 50736D778E + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 01:59:08 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 78305-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 05:59:07 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.invendra.net (sbx-01.invendra.net [66.139.76.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 8D34EDBE01 + for <pgsql-performance@postgresql.org>; + Sun, 27 Nov 2005 01:59:05 -0400 (AST) +Received: from david.lang.hm (dsl081-044-215.lax1.dsl.speakeasy.net + [64.81.44.215]) + by mail.invendra.net (Postfix) with ESMTP id 15F3B1AC3E9 + for <pgsql-performance@postgresql.org>; + Sat, 26 Nov 2005 21:59:25 -0800 (PST) +Date: Sat, 26 Nov 2005 10:51:18 -0800 (PST) +From: David Lang <dlang@invendra.net> +X-X-Sender: dlang@david.lang.hm +To: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +Message-ID: <Pine.LNX.4.62.0511261040500.2790@qnivq.ynat.uz> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.746 required=5 tests=[DATE_IN_PAST_06_12=0.746] +X-Spam-Score: 0.746 +X-Spam-Level: +X-Archive-Number: 200511/523 +X-Sequence-Number: 15780 + +>Another thought - I priced out a maxed out machine with 16 cores and +>128GB of RAM and 1.5TB of usable disk - $71,000. +> +>You could instead buy 8 machines that total 16 cores, 128GB RAM and 28TB +>of disk for $48,000, and it would be 16 times faster in scan rate, which +>is the most important factor for large databases. The size would be 16 +>rack units instead of 5, and you'd have to add a GigE switch for $1500. +> +>Scan rate for above SMP: 200MB/s +> +>Scan rate for above cluster: 3,200Mb/s +> +>You could even go dual core and double the memory on the cluster and +>you'd about match the price of the "god box". +> +>- Luke + +Luke, I assume you are talking about useing the Greenplum MPP for this +(otherwise I don't know how you are combining all the different systems). + +If you are, then you are overlooking one very significant factor, the cost +of the MPP software, at $10/cpu the cluster has an extra $160K in software +costs, which is double the hardware costs. + +if money is no object then go for it, but if it is then you comparison +would be (ignoring software maintinance costs) the 16 core 128G ram system +vs ~3xsmall systems totaling 6 cores and 48G ram. + +yes if scan speed is the bottleneck you still win with the small systems, +but for most other uses the large system would win easily. and in any case +it's not the open and shut case that you keep presenting it as. + +David Lang + +From pgsql-performance-owner@postgresql.org Sat Nov 26 14:57:01 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id ACC32DBDC5 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 26 Nov 2005 14:57:00 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 83125-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 26 Nov 2005 18:57:00 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by svr1.postgresql.org (Postfix) with ESMTP id A443DDBDD9 + for <pgsql-performance@postgresql.org>; + Sat, 26 Nov 2005 14:56:57 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id 379BF308DA; Sat, 26 Nov 2005 19:56:58 +0100 (MET) +From: "Qingqing Zhou" <zhouqq@cs.toronto.edu> +X-Newsgroups: pgsql.performance +Subject: Re: Open request for benchmarking input +Date: Sat, 26 Nov 2005 13:57:47 -0500 +Organization: Hub.Org Networking Services +Lines: 38 +Message-ID: <dmab5n$226n$1@news.hub.org> +References: <Pine.LNX.4.64.0511261025140.16022@discord.dyndns.org> +X-Complaints-To: usenet@news.hub.org +X-Priority: 3 +X-MSMail-Priority: Normal +X-Newsreader: Microsoft Outlook Express 6.00.2900.2180 +X-RFC2646: Format=Flowed; Response +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.055 required=5 tests=[AWL=0.055] +X-Spam-Score: 0.055 +X-Spam-Level: +X-Archive-Number: 200511/516 +X-Sequence-Number: 15773 + + +"Jeff Frost" <jeff@frostconsultingllc.com> wrote +> +> Did you folks see this article on Slashdot with a fellow requesting input +> on what sort of benchmarks to run to get a good Postgresql vs Mysql +> dataset? Perhaps this would be a good opportunity for us to get some good +> benchmarking done. +> "The hardware I have available is as follows: +> +> * 2x dual Opteron 8G ram, 2x144G 15Krpm SCSI +> * 2x dual Opteron 8G ram, 2x72G 15Krpm SCSI +> * 1x dual Opteron 16G ram, 2x36G 15Krpm SCSI 16x400G 7200rpm SATA +> + +I see this as a good chance to evaluate and boost PostgreSQL performance in +general. + +My two concerns: +(1) How long will David Lang spend on the benchmarking? We need *continous* +feedback after each tuning. This is important and Mark Wong has done great +job on this. +(2) The hardware configuration may not reflect all potentials of PostgreSQL. +For example, so far, PostgreSQL does not pay much attention in reducing I/O +cost, so a stronger RAID definitely will benefit PostgreSQL performance. + +> +> For my own interests, I would like to at least cover the following bases: +> 32 bit vs 64 bit vs 64 bit kernel + 32 bit user-space; data warehouse type +> tests (data >> memory); and web prefs test (active data RAM) +> + +Don't forget TPCC (data > memory, with intensive updates). So the benchmarks +in my mind include TPCC, TPCH and TPCW. + +Regards, +Qingqing + + + +From pgsql-performance-owner@postgresql.org Sun Nov 27 02:42:05 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 19372DA7F3 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 02:42:04 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 82569-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 06:42:03 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.invendra.net (sbx-01.invendra.net [66.139.76.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 80EEBDA7E2 + for <pgsql-performance@postgresql.org>; + Sun, 27 Nov 2005 02:42:01 -0400 (AST) +Received: from david.lang.hm (dsl081-044-215.lax1.dsl.speakeasy.net + [64.81.44.215]) + by mail.invendra.net (Postfix) with ESMTP id 3AA811AC3E9; + Sat, 26 Nov 2005 22:42:21 -0800 (PST) +Date: Sat, 26 Nov 2005 11:34:14 -0800 (PST) +From: David Lang <dlang@invendra.net> +X-X-Sender: dlang@david.lang.hm +To: Luke Lonergan <LLonergan@greenplum.com> +Cc: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +In-Reply-To: <3E37B936B592014B978C4415F90D662DE11EBC@MI8NYCMAIL06.Mi8.com> +Message-ID: <Pine.LNX.4.62.0511261129040.2790@qnivq.ynat.uz> +References: <3E37B936B592014B978C4415F90D662DE11EBC@MI8NYCMAIL06.Mi8.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.746 required=5 tests=[DATE_IN_PAST_06_12=0.746] +X-Spam-Score: 0.746 +X-Spam-Level: +X-Archive-Number: 200511/525 +X-Sequence-Number: 15782 + +On Sun, 27 Nov 2005, Luke Lonergan wrote: + +> For data warehousing its pretty well open and shut. To use all cpus and +> io channels on each query you will need mpp. +> +> Has anyone done the math.on the original post? 5TB takes how long to +> scan once? If you want to wait less than a couple of days just for a +> seq scan, you'd better be in the multi-gb per second range. + +if you truely need to scan the entire database then you are right, however +indexes should be able to cut the amount you need to scan drasticly. + +David Lang + +From pgsql-performance-owner@postgresql.org Sat Nov 26 16:17:09 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id B9AB3D7A7E + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 26 Nov 2005 16:17:07 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 94524-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 26 Nov 2005 20:17:07 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id 5EE81D6ED8 + for <pgsql-performance@postgresql.org>; + Sat, 26 Nov 2005 16:17:03 -0400 (AST) +Received: from 172.16.1.112 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Sat, 26 Nov 2005 15:16:50 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.160]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Sat, 26 Nov + 2005 15:15:29 -0500 +Received: from 208.54.15.129 ([208.54.15.129]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.106]) with Microsoft Exchange Server HTTP-DAV ; Sat, 26 Nov + 2005 20:15:29 +0000 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Sat, 26 Nov 2005 12:15:28 -0800 +Subject: Re: Open request for benchmarking input +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Qingqing Zhou" <zhouqq@cs.toronto.edu>, pgsql-performance@postgresql.org +Message-ID: <BFAE0260.147E6%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Open request for benchmarking input +Thread-Index: AcXyxiSDYvHeB165EdqEvAANk63kWA== +In-Reply-To: <dmab5n$226n$1@news.hub.org> +MIME-Version: 1.0 +X-OriginalArrivalTime: 26 Nov 2005 20:15:29.0535 (UTC) + FILETIME=[256E28F0:01C5F2C6] +X-WSS-ID: 6F961D3B2UO5510355-07-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=2.398 required=5 tests=[AWL=-0.091, + RCVD_IN_SORBS_WEB=1.236, RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 2.398 +X-Spam-Level: ** +X-Archive-Number: 200511/517 +X-Sequence-Number: 15774 + +Jeff, Qingqing, + +On 11/26/05 10:57 AM, "Qingqing Zhou" <zhouqq@cs.toronto.edu> wrote: + +> +> "Jeff Frost" <jeff@frostconsultingllc.com> wrote +>> +>> Did you folks see this article on Slashdot with a fellow requesting input +>> on what sort of benchmarks to run to get a good Postgresql vs Mysql +>> dataset? Perhaps this would be a good opportunity for us to get some good +>> benchmarking done. +>> "The hardware I have available is as follows: +>> +>> * 2x dual Opteron 8G ram, 2x144G 15Krpm SCSI +>> * 2x dual Opteron 8G ram, 2x72G 15Krpm SCSI +>> * 1x dual Opteron 16G ram, 2x36G 15Krpm SCSI 16x400G 7200rpm SATA +>> + +I suggest specifying a set of basic system / HW benchmarks to baseline the +hardware before each benchmark is run. This has proven to be a major issue +with most performance tests. My pick for I/O is bonnie++. + +Your equipment allows you the opportunity to benchmark all 5 machines +running together as a cluster - this is important to measure maturity of +solutions for high performance warehousing. Greenplum can provide you a +license for Bizgres MPP for this purpose. + +> (2) The hardware configuration may not reflect all potentials of PostgreSQL. +> For example, so far, PostgreSQL does not pay much attention in reducing I/O +> cost, so a stronger RAID definitely will benefit PostgreSQL performance. + +The 16x SATA drives should be great, provided you have a high performance +RAID adapter configured properly. You should be able to get 800MB/s of +sequential scan performance by using a card like the 3Ware 9550SX. I've +also heard that the Areca cards are good (how good?). Configuration of the +I/O must be validated though - I've seen as low as 25MB/s from a +misconfigured system. + +>> For my own interests, I would like to at least cover the following bases: +>> 32 bit vs 64 bit vs 64 bit kernel + 32 bit user-space; data warehouse type +>> tests (data >> memory); and web prefs test (active data RAM) +>> +> +> Don't forget TPCC (data > memory, with intensive updates). So the benchmarks +> in my mind include TPCC, TPCH and TPCW. + +I agree with Qingqing, though I think the OSTG DBT-3 (very similar to TPC-H) +is sufficient for data warehousing. + +This is a fairly ambitious project - one problem I see is that MySQL may not +run all of these benchmarks, particularly the DBT-3. Also - would the rules +allow for mixing / matching pluggable features of the DBMS? Innodb versus +MyISAM? + +- Luke + + + +From pgsql-performance-owner@postgresql.org Sat Nov 26 16:31:41 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 435E3D8D18 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 26 Nov 2005 16:31:40 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 01625-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 26 Nov 2005 20:31:40 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtpauth10.mail.atl.earthlink.net + (smtpauth10.mail.atl.earthlink.net [209.86.89.70]) + by svr1.postgresql.org (Postfix) with ESMTP id 4F5D5D7A7E + for <pgsql-performance@postgresql.org>; + Sat, 26 Nov 2005 16:31:37 -0400 (AST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; + d=earthlink.net; + b=RiLeNQ1+vLZ+KGjVed+j1DCIP+SYXTwSmPPVXUYGHCFn+BuSSx3t03sH0sIxAxEE; + h=Received:Message-Id:X-Mailer:Date:To:From:Subject:In-Reply-To:References:Mime-Version:Content-Type:X-ELNK-Trace:X-Originating-IP; +Received: from [71.243.20.20] (helo=ron-6d52adff2a6.earthlink.net) + by smtpauth10.mail.atl.earthlink.net with asmtp (Exim 4.34) + id 1Eg6ht-0003sl-HC; Sat, 26 Nov 2005 15:31:37 -0500 +Message-Id: <6.2.5.6.0.20051126152139.01d97350@earthlink.net> +X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6 +Date: Sat, 26 Nov 2005 15:31:33 -0500 +To: "Luke Lonergan" <llonergan@greenplum.com>, + pgsql-performance@postgresql.org +From: Ron <rjpeace@earthlink.net> +Subject: Re: Open request for benchmarking input +In-Reply-To: <BFAE0260.147E6%llonergan@greenplum.com> +References: <dmab5n$226n$1@news.hub.org> + <BFAE0260.147E6%llonergan@greenplum.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset="us-ascii"; format=flowed +X-ELNK-Trace: + acd68a6551193be5d780f4a490ca69563f9fea00a6dd62bc6cd3634bb62a8cbfc2259616b14a72d1350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c +X-Originating-IP: 71.243.20.20 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.12 required=5 tests=[AWL=0.120] +X-Spam-Score: 0.12 +X-Spam-Level: +X-Archive-Number: 200511/518 +X-Sequence-Number: 15775 + +At 03:15 PM 11/26/2005, Luke Lonergan wrote: + +>I suggest specifying a set of basic system / HW benchmarks to baseline the +>hardware before each benchmark is run. This has proven to be a major issue +>with most performance tests. My pick for I/O is bonnie++. +> +>Your equipment allows you the opportunity to benchmark all 5 machines +>running together as a cluster - this is important to measure maturity of +>solutions for high performance warehousing. Greenplum can provide you a +>license for Bizgres MPP for this purpose. +...and detailed config / tuning specs as well for it or everyone is +probably wasting their time. For instance, it seems fairly clear +that the default 8KB table size and default read ahead size are both +pessimal, at least for non OLTP-like apps. In addition, there's been +a reasonable amount of evidence that xfs should be the file system of +choice for pg. + +Things like optimal RAID strip size, how to allocate tables to +various IO HW, and what levels of RAID to use for each RAID set also +have to be defined. + + +>The 16x SATA drives should be great, provided you have a high performance +>RAID adapter configured properly. You should be able to get 800MB/s of +>sequential scan performance by using a card like the 3Ware 9550SX. I've +>also heard that the Areca cards are good (how good?). Configuration of the +>I/O must be validated though - I've seen as low as 25MB/s from a +>misconfigured system. +The Areca cards, particularly with 1-2GB of buffer cache, are the +current commodity RAID controller performance leader. Better +performance can be gotten out of HW from vendors like Xyratex, but it +will cost much more. + + +Ron + + + +From pgsql-performance-owner@postgresql.org Sat Nov 26 20:12:04 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 60F0FDA5AF + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sat, 26 Nov 2005 20:12:03 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 34708-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 00:12:05 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from moutng.kundenserver.de (moutng.kundenserver.de + [212.227.126.177]) + by svr1.postgresql.org (Postfix) with ESMTP id 61445DA531 + for <pgsql-performance@postgresql.org>; + Sat, 26 Nov 2005 20:11:59 -0400 (AST) +Received: from [84.143.22.121] (helo=pse.dyndns.org) + by mrelayeu.kundenserver.de (node=mrelayeu6) with ESMTP (Nemesis), + id 0ML29c-1EgA9C393d-0002u4; Sun, 27 Nov 2005 01:12:02 +0100 +Received: from pse1 ([192.168.0.3]) by pse.dyndns.org with esmtp (Exim 4.44) + id 1EgA9B-0001gC-Gq; Sun, 27 Nov 2005 01:12:01 +0100 +Message-ID: <4388F9D1.6080609@pse-consulting.de> +Date: Sun, 27 Nov 2005 00:12:01 +0000 +From: Andreas Pflug <pgadmin@pse-consulting.de> +User-Agent: Mozilla Thunderbird 1.0 (X11/20041206) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Qingqing Zhou <zhouqq@cs.toronto.edu> +CC: pgsql-performance@postgresql.org +Subject: Re: Open request for benchmarking input +References: <Pine.LNX.4.64.0511261025140.16022@discord.dyndns.org> + <dmab5n$226n$1@news.hub.org> +In-Reply-To: <dmab5n$226n$1@news.hub.org> +X-Enigmail-Version: 0.89.5.0 +X-Enigmail-Supports: pgp-inline, pgp-mime +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Provags-ID: kundenserver.de abuse@kundenserver.de + login:0ce7ee5c3478b8d72edd8e05ccd40b70 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.033 required=5 tests=[AWL=0.033] +X-Spam-Score: 0.033 +X-Spam-Level: +X-Archive-Number: 200511/519 +X-Sequence-Number: 15776 + +Qingqing Zhou wrote: +> "Jeff Frost" <jeff@frostconsultingllc.com> wrote + +>> "The hardware I have available is as follows: +>> +>> * 2x dual Opteron 8G ram, 2x144G 15Krpm SCSI +>> * 2x dual Opteron 8G ram, 2x72G 15Krpm SCSI +>> * 1x dual Opteron 16G ram, 2x36G 15Krpm SCSI 16x400G 7200rpm SATA +>> +> (2) The hardware configuration may not reflect all potentials of PostgreSQL. + +These boxes don't look like being designed for a DB server. The first +are very CPU bound, and the third may be a good choice for very large +amounts of streamed data, but not optimal for TP random access. + +Hopefully, when publicly visible benchmarks are performed, machines are +used that comply with common engineering knowledge, ignoring those guys +who still believe that sequential performance is the most important +issue on disk subsystems for DBMS. + +Regards, +Andreas + +From pgsql-performance-owner@postgresql.org Sun Nov 27 02:28:35 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 97B97DBE0D + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 02:28:34 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 82559-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 06:28:33 +0000 (GMT) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw01.mi8.com [63.240.6.47]) + by svr1.postgresql.org (Postfix) with ESMTP id 6369CDBE27 + for <pgsql-performance@postgresql.org>; + Sun, 27 Nov 2005 02:28:31 -0400 (AST) +Received: from 172.16.1.112 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D1)); Sun, 27 Nov 2005 01:28:21 -0500 +X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.160]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Sun, 27 Nov + 2005 01:18:56 -0500 +X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Sun, 27 Nov 2005 01:18:54 -0500 +Message-ID: <3E37B936B592014B978C4415F90D662DE11EBC@MI8NYCMAIL06.Mi8.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXzF8NDXvQ92WFDRy2E6gcFtbBBQAAAq3Jp +From: "Luke Lonergan" <LLonergan@greenplum.com> +To: dlang@invendra.net, + pgsql-performance@postgresql.org +X-OriginalArrivalTime: 27 Nov 2005 06:18:56.0403 (UTC) + FILETIME=[7267C630:01C5F31A] +X-WSS-ID: 6F978E743284409080-15-01 +Content-Type: text/plain; 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+ charset=utf-8 +Content-Transfer-Encoding: base64 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.037 required=5 tests=[AWL=0.037] +X-Spam-Score: 0.037 +X-Spam-Level: +X-Archive-Number: 200511/526 +X-Sequence-Number: 15783 + +SGF2ZSB5b3UgZmFjdG9yZWQgaW4gaG93IGxvbmcgaXQgdGFrZXMgdG8gYnVpbGQgYW4gaW5kZXgg +b24gNVRCPyAgQW5kIHRoZSBpbmRleCBzaXplPw0KDQpSZWFsbHksIGl0J3MgYSB3aG9sZSBkaWZm +ZXJlbnQgd29ybGQgYXQgbXVsdGktVEIsIGV2ZXJ5dGhpbmcgaGFzIHRvIHNjYWxlLg0KDQpCdHcg +d2UgZG9uJ3QganVzdCBzY2FuIGluIHBhcmFsbGVsLCB3ZSBkbyBhbGwgaW4gcGFyYWxsZWwsIGNo +ZWNrIHRoZSBzb3J0IG51bWJlciBvbiB0aGlzIHRocmVhZC4gIE1wcCBpcyBmb3IgdGhlIGdvZCBi +b3ggdG9vLg0KDQpBbmQgeW91ciBwcmljZSBpcyB3cm9uZyAtIGJ1dCBpZiB5b3Ugd2FudCBmcmVl +IHRoZW4geW91J2xsIGhhdmUgdG8gZmluZCBhbm90aGVyIHdheSB0byBnZXQgeW91ciB3b3JrIGRv +bmUuDQoNCi0gTHVrZQ0KLSBMdWtlDQotLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLQ0KU2VudCBm +cm9tIG15IEJsYWNrQmVycnkgV2lyZWxlc3MgRGV2aWNlDQoNCg0KLS0tLS1PcmlnaW5hbCBNZXNz +YWdlLS0tLS0NCkZyb206IERhdmlkIExhbmcgPGRsYW5nQGludmVuZHJhLm5ldD4NClRvOiBMdWtl +IExvbmVyZ2FuIDxMTG9uZXJnYW5AZ3JlZW5wbHVtLmNvbT4NCkNDOiBwZ3NxbC1wZXJmb3JtYW5j +ZUBwb3N0Z3Jlc3FsLm9yZyA8cGdzcWwtcGVyZm9ybWFuY2VAcG9zdGdyZXNxbC5vcmc+DQpTZW50 +OiBTYXQgTm92IDI2IDE0OjM0OjE0IDIwMDUNClN1YmplY3Q6IFJlOiBbUEVSRk9STV0gSGFyZHdh +cmUvT1MgcmVjb21tZW5kYXRpb25zIGZvciBsYXJnZSBkYXRhYmFzZXMgKA0KDQpPbiBTdW4sIDI3 +IE5vdiAyMDA1LCBMdWtlIExvbmVyZ2FuIHdyb3RlOg0KDQo+IEZvciBkYXRhIHdhcmVob3VzaW5n +IGl0cyBwcmV0dHkgd2VsbCBvcGVuIGFuZCBzaHV0LiAgVG8gdXNlIGFsbCBjcHVzIGFuZCANCj4g +aW8gY2hhbm5lbHMgb24gZWFjaCBxdWVyeSB5b3Ugd2lsbCBuZWVkIG1wcC4NCj4NCj4gSGFzIGFu +eW9uZSBkb25lIHRoZSBtYXRoLm9uIHRoZSBvcmlnaW5hbCBwb3N0PyAgNVRCIHRha2VzIGhvdyBs +b25nIHRvIA0KPiBzY2FuIG9uY2U/ICBJZiB5b3Ugd2FudCB0byB3YWl0IGxlc3MgdGhhbiBhIGNv +dXBsZSBvZiBkYXlzIGp1c3QgZm9yIGEgDQo+IHNlcSBzY2FuLCB5b3UnZCBiZXR0ZXIgYmUgaW4g +dGhlIG11bHRpLWdiIHBlciBzZWNvbmQgcmFuZ2UuDQoNCmlmIHlvdSB0cnVlbHkgbmVlZCB0byBz +Y2FuIHRoZSBlbnRpcmUgZGF0YWJhc2UgdGhlbiB5b3UgYXJlIHJpZ2h0LCBob3dldmVyIA0KaW5k +ZXhlcyBzaG91bGQgYmUgYWJsZSB0byBjdXQgdGhlIGFtb3VudCB5b3UgbmVlZCB0byBzY2FuIGRy +YXN0aWNseS4NCg0KRGF2aWQgTGFuZw0KDQo= + + +From pgsql-performance-owner@postgresql.org Sun Nov 27 18:16:12 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 12009DAF71 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 18:16:12 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 37475-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 18:16:12 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.invendra.net (sbx-01.invendra.net [66.139.76.16]) + by svr1.postgresql.org (Postfix) with ESMTP id 73CF7DAEDD + for <pgsql-performance@postgresql.org>; + Sun, 27 Nov 2005 18:16:05 -0400 (AST) +Received: from david.lang.hm (dsl081-044-215.lax1.dsl.speakeasy.net + [64.81.44.215]) + by mail.invendra.net (Postfix) with ESMTP id D87871AC3E9; + Sun, 27 Nov 2005 14:16:26 -0800 (PST) +Date: Sun, 27 Nov 2005 03:08:17 -0800 (PST) +From: David Lang <dlang@invendra.net> +X-X-Sender: dlang@david.lang.hm +To: Andreas Pflug <pgadmin@pse-consulting.de> +Cc: pgsql-performance@postgresql.org +Subject: Re: Open request for benchmarking input +In-Reply-To: <4389A4D4.6030203@pse-consulting.de> +Message-ID: <Pine.LNX.4.62.0511270304590.2790@qnivq.ynat.uz> +References: <Pine.LNX.4.62.0511260745370.2790@qnivq.ynat.uz> + <4389A4D4.6030203@pse-consulting.de> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.746 required=5 tests=[DATE_IN_PAST_06_12=0.746] +X-Spam-Score: 0.746 +X-Spam-Level: +X-Archive-Number: 200511/534 +X-Sequence-Number: 15791 + +On Sun, 27 Nov 2005, Andreas Pflug wrote: + +> David Lang wrote: +>> +>> Postgres needs to work on the low end stuff as well as the high end stuff +>> or people will write their app to work with things that DO run on low end +>> hardware and they spend much more money then is needed to scale the +>> hardware up rather then re-writing their app. +> +> I agree that pgsql runs on low end stuff, but a dual Opteron with 2x15kSCSI +> isn't low end, is it? The CPU/IO performance isn't balanced for the total +> cost, you probably could get a single CPU/6x15kRPM machine for the same price +> delivering better TP performance in most scenarios. +> +> Benchmarks should deliver results that are somewhat comparable. If performed +> on machines that don't deliver a good CPU/IO power balance for the type of DB +> load being tested, they're misleading and hardly usable for comparision +> purposes, and even less for learning how to configure a decent server since +> you might have to tweak some parameters in an unusual way. + +a couple things to note, + +first, when running benchmarks there is a need for client machines to +stress the database, these machines are what are available to be clients +as well as servers. + +second, the smaller machines are actually about what I would spec out for +a high performance database that's reasonably small, a couple of the boxes +have 144G drives, if they are setup as raid1 then the boxes would be +reasonable to use for a database up to 50G or larger (assuming you need +space on the DB server to dump the database, up to 100G or so if you +don't) + +David Lang + +From pgsql-performance-owner@postgresql.org Sun Nov 27 08:16:33 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 1F9EFDC51B + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 08:16:32 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 15572-06-5 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 08:16:24 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from cassarossa.samfundet.no (cassarossa.samfundet.no + [129.241.93.19]) + by svr1.postgresql.org (Postfix) with ESMTP id 70D7ADBB13 + for <pgsql-performance@postgresql.org>; + Sun, 27 Nov 2005 07:52:37 -0400 (AST) +Received: from trofast.ipv6.sesse.net ([2001:700:300:dc03:20e:cff:fe36:a766] + helo=trofast.sesse.net) + by cassarossa.samfundet.no with esmtp (Exim 4.50) id 1EgL59-0002Rp-M3 + for pgsql-performance@postgresql.org; Sun, 27 Nov 2005 12:52:35 +0100 +Received: from sesse by trofast.sesse.net with local (Exim 3.36 #1 (Debian)) + id 1EgL4V-0004lE-00 + for <pgsql-performance@postgresql.org>; Sun, 27 Nov 2005 12:51:55 +0100 +Date: Sun, 27 Nov 2005 12:51:55 +0100 +From: "Steinar H. Gunderson" <sgunderson@bigfoot.com> +To: pgsql-performance@postgresql.org +Subject: Re: Open request for benchmarking input +Message-ID: <20051127115155.GB18128@uio.no> +Mail-Followup-To: pgsql-performance@postgresql.org +References: <Pine.LNX.4.64.0511261025140.16022@discord.dyndns.org> + <dmab5n$226n$1@news.hub.org> +MIME-Version: 1.0 +Content-Type: text/plain; charset=utf-8 +Content-Disposition: inline +In-Reply-To: <dmab5n$226n$1@news.hub.org> +X-Operating-System: Linux 2.6.14 on a i686 +X-Message-Flag: Outlook? --> http://www.mozilla.org/products/thunderbird/ +User-Agent: Mutt/1.5.11 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/527 +X-Sequence-Number: 15784 + +On Sat, Nov 26, 2005 at 01:57:47PM -0500, Qingqing Zhou wrote: +> Don't forget TPCC (data > memory, with intensive updates). So the benchmarks +> in my mind include TPCC, TPCH and TPCW. + +I'm lost in all those acronyms, but am I right in assuming that none of these +actually push the planner very hard? We keep on pushing that "PostgreSQL is a +lot better than MySQL when it comes to many joins and complex queries" +(mostly because the planner is a lot more mature -- does MySQL even keep +statistics yet?), but I'm not sure if there are any widely used benchmarks +available that actaully excercise that. + +/* Steinar */ +-- +Homepage: http://www.sesse.net/ + +From pgsql-performance-owner@postgresql.org Sun Nov 27 08:21:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 27D35DAEDD + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 08:21:46 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 16374-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 08:21:44 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from moutng.kundenserver.de (moutng.kundenserver.de + [212.227.126.177]) + by svr1.postgresql.org (Postfix) with ESMTP id 4B818DA85A + for <pgsql-performance@postgresql.org>; + Sun, 27 Nov 2005 08:21:43 -0400 (AST) +Received: from [84.143.46.71] (helo=pse.dyndns.org) + by mrelayeu.kundenserver.de (node=mrelayeu7) with ESMTP (Nemesis), + id 0ML2Dk-1EgLXK2yBB-0002gx; Sun, 27 Nov 2005 13:21:43 +0100 +Received: from pse1 ([192.168.0.3]) by pse.dyndns.org with esmtp (Exim 4.44) + id 1EgLXJ-0001nu-1W; Sun, 27 Nov 2005 13:21:41 +0100 +Message-ID: <4389A4D4.6030203@pse-consulting.de> +Date: Sun, 27 Nov 2005 13:21:40 +0100 +From: Andreas Pflug <pgadmin@pse-consulting.de> +User-Agent: Mozilla Thunderbird 1.0 (X11/20041206) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: David Lang <dlang@invendra.net> +CC: pgsql-performance@postgresql.org +Subject: Re: Open request for benchmarking input +References: <Pine.LNX.4.62.0511260745370.2790@qnivq.ynat.uz> +In-Reply-To: <Pine.LNX.4.62.0511260745370.2790@qnivq.ynat.uz> +X-Enigmail-Version: 0.89.5.0 +X-Enigmail-Supports: pgp-inline, pgp-mime +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Provags-ID: kundenserver.de abuse@kundenserver.de + login:0ce7ee5c3478b8d72edd8e05ccd40b70 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.031 required=5 tests=[AWL=0.031] +X-Spam-Score: 0.031 +X-Spam-Level: +X-Archive-Number: 200511/528 +X-Sequence-Number: 15785 + +David Lang wrote: +>> These boxes don't look like being designed for a DB server. The first +>> are very CPU bound, and the third may be a good choice for very large +>> amounts of streamed data, but not optimal for TP random access. +> +> +> I don't know what you mean when you say that the first ones are CPU +> bound, they have far more CPU then they do disk I/O +> +> however I will agree that they were not designed to be DB servers, they +> weren't. they happen to be the machines that I have available. + +That was what I understood from the specs. +> +> they only have a pair of disks each, which would not be reasonable for +> most production DB uses, and they have far more CPU then is normally +> reccomended. So I'll have to run raid 0 instead of 0+1 (or not use raid) +> which would be unacceptable in a production environment, but can still +> give some useful info. + > +> the 5th box _was_ purchased to be a DB server, but one to store and +> analyse large amounts of log data, so large amounts of data storage were +> more important then raw DB performance (although we did max out the RAM +> at 16G to try and make up for it). it was a deliberate price/performance +> tradeoff. this machine ran ~$20k, but a similar capacity with SCSI +> drives would have been FAR more expensive (IIRC a multiple of 4x or more +> more expensive). + +That was my understanding too. For this specific requirement, I'd +probably design the server the same way, and running OLAP benchmarks +against it sounds very reasonable. + +> +>> Hopefully, when publicly visible benchmarks are performed, machines +>> are used that comply with common engineering knowledge, ignoring those +>> guys who still believe that sequential performance is the most +>> important issue on disk subsystems for DBMS. +> +> +> are you saying that I shouldn't do any benchmarks becouse the machines +> aren't what you would consider good enough? +> +> if so I disagree with you and think that benchmarks should be done on +> even worse machines, but should also be done on better machines. (are +> you volunteering to provide time on better machines for benchmarks?) +> +> not everyone will buy a lot of high-end hardware before they start +> useing a database. in fact most companies will start with a database on +> lower end hardware and then as their requirements grow they will move to +> better hardware. I'm willing to bet that what I have available is better +> then the starting point for most places. +> +> Postgres needs to work on the low end stuff as well as the high end +> stuff or people will write their app to work with things that DO run on +> low end hardware and they spend much more money then is needed to scale +> the hardware up rather then re-writing their app. + +I agree that pgsql runs on low end stuff, but a dual Opteron with +2x15kSCSI isn't low end, is it? The CPU/IO performance isn't balanced +for the total cost, you probably could get a single CPU/6x15kRPM machine +for the same price delivering better TP performance in most scenarios. + +Benchmarks should deliver results that are somewhat comparable. If +performed on machines that don't deliver a good CPU/IO power balance for +the type of DB load being tested, they're misleading and hardly usable +for comparision purposes, and even less for learning how to configure a +decent server since you might have to tweak some parameters in an +unusual way. + +Regards, +Andreas + +From pgsql-performance-owner@postgresql.org Sun Nov 27 11:48:02 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 11884DBF48 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 11:48:02 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 43888-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 11:48:02 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from megazone.bigpanda.com (megazone.bigpanda.com [64.147.171.210]) + by svr1.postgresql.org (Postfix) with ESMTP id A1248D7798 + for <pgsql-performance@postgresql.org>; + Sun, 27 Nov 2005 11:47:59 -0400 (AST) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id CFEF4356C6; Sun, 27 Nov 2005 07:48:01 -0800 (PST) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id CE6D635163; Sun, 27 Nov 2005 07:48:01 -0800 (PST) +Date: Sun, 27 Nov 2005 07:48:01 -0800 (PST) +From: Stephan Szabo <sszabo@megazone.bigpanda.com> +To: Luke Lonergan <LLonergan@greenplum.com> +Cc: dlang@invendra.net, pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +In-Reply-To: <3E37B936B592014B978C4415F90D662DE11EBC@MI8NYCMAIL06.Mi8.com> +Message-ID: <20051127072933.Q62040@megazone.bigpanda.com> +References: <3E37B936B592014B978C4415F90D662DE11EBC@MI8NYCMAIL06.Mi8.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/529 +X-Sequence-Number: 15786 + +On Sun, 27 Nov 2005, Luke Lonergan wrote: + +> Has anyone done the math.on the original post? 5TB takes how long to +> scan once? If you want to wait less than a couple of days just for a +> seq scan, you'd better be in the multi-gb per second range. + +Err, I get about 31 megabytes/second to do 5TB in 170,000 seconds. I think +perhaps you were exaggerating a bit or adding additional overhead not +obvious from the above. ;) + +--- + +At 1 gigabyte per second, 1 terrabyte should take about 1000 seconds +(between 16 and 17 minutes). The impressive 3.2 gigabytes per second +listed before (if it actually scans consistently at that rate), puts it at +a little over 5 minutes I believe for 1, so about 26 for 5 terrabytes. +The 200 megabyte per second number puts it about 7 hours for 5 +terrabytes AFAICS. + +From pgsql-performance-owner@postgresql.org Sun Nov 27 13:10:56 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 16F75DBFCF + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 13:10:56 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 68560-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 13:10:54 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtpauth07.mail.atl.earthlink.net + (smtpauth07.mail.atl.earthlink.net [209.86.89.67]) + by svr1.postgresql.org (Postfix) with ESMTP id 7E7F5D7798 + for <pgsql-performance@postgresql.org>; + Sun, 27 Nov 2005 13:10:53 -0400 (AST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; + d=earthlink.net; + b=smSxls9bRxZLcZV7ZCzkGfNTQWHVqHCoNt55GX1uxE9XpY0N3PWE1SE/C83UkIQI; + h=Received:Message-Id:X-Mailer:Date:To:From:Subject:In-Reply-To:References:Mime-Version:Content-Type:X-ELNK-Trace:X-Originating-IP; +Received: from [70.22.193.119] (helo=ron-6d52adff2a6.earthlink.net) + by smtpauth07.mail.atl.earthlink.net with asmtp (Exim 4.34) + id 1EgQ3A-0003wt-0m; Sun, 27 Nov 2005 12:10:52 -0500 +Message-Id: <6.2.5.6.0.20051127114155.01dbf868@earthlink.net> +X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6 +Date: Sun, 27 Nov 2005 12:10:44 -0500 +To: "Luke Lonergan" <LLonergan@greenplum.com>, + pgsql-performance@postgresql.org +From: Ron <rjpeace@earthlink.net> +Subject: Re: Hardware/OS recommendations for large databases +In-Reply-To: <3E37B936B592014B978C4415F90D662DE11EBC@MI8NYCMAIL06.Mi8.co + m> +References: <3E37B936B592014B978C4415F90D662DE11EBC@MI8NYCMAIL06.Mi8.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset="us-ascii"; format=flowed +X-ELNK-Trace: + acd68a6551193be5d780f4a490ca69563f9fea00a6dd62bcdbd45f42b791e69503975ada0daad77b350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c +X-Originating-IP: 70.22.193.119 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.359 required=5 tests=[AWL=-0.120, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.359 +X-Spam-Level: +X-Archive-Number: 200511/530 +X-Sequence-Number: 15787 + +At 01:18 AM 11/27/2005, Luke Lonergan wrote: +>For data warehousing its pretty well open and shut. To use all cpus +>and io channels on each query you will need mpp. +> +>Has anyone done the math.on the original post? 5TB takes how long +>to scan once? If you want to wait less than a couple of days just +>for a seq scan, you'd better be in the multi-gb per second range. +More than a bit of hyperbole there Luke. + +Some common RW scenarios: +Dual 1GbE NICs => 200MBps => 5TB in 5x10^12/2x10^8= 25000secs= +~6hrs57mins. Network stuff like re-transmits of dropped packets can +increase this, so network SLA's are critical. + +Dual 10GbE NICs => ~1.6GBps (10GbE NICs can't yet do over ~800MBps +apiece) => 5x10^12/1.6x10^9= 3125secs= ~52mins. SLA's are even +moire critical here. + +If you are pushing 5TB around on a regular basis, you are not wasting +your time & money on commodity <= 300MBps RAID HW. You'll be using +800MBps and 1600MBps high end stuff, which means you'll need ~1-2hrs +to sequentially scan 5TB on physical media. + +Clever use of RAM can get a 5TB sequential scan down to ~17mins. + +Yes, it's a lot of data. But sequential scan times should be in the +mins or low single digit hours, not days. Particularly if you use +RAM to maximum advantage. + +Ron + + + +From pgsql-performance-owner@postgresql.org Sun Nov 27 15:14:04 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 8BB81DC58A + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 15:14:03 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 13682-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 15:14:02 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.Mi8.com (d01gw03.mi8.com [63.240.6.42]) + by svr1.postgresql.org (Postfix) with ESMTP id C182ADC5D7 + for <pgsql-performance@postgresql.org>; + Sun, 27 Nov 2005 15:14:00 -0400 (AST) +Received: from 172.16.1.110 by mail.Mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D3)); Sun, 27 Nov 2005 14:13:51 -0500 +X-Server-Uuid: E847189C-FC88-4913-9CD4-DE66914F83C0 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.160]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Sun, 27 Nov + 2005 14:11:53 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.106]) with Microsoft Exchange Server HTTP-DAV ; Sun, 27 Nov + 2005 19:11:53 +0000 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Sun, 27 Nov 2005 11:11:53 -0800 +Subject: Re: Hardware/OS recommendations for large databases +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Ron" <rjpeace@earthlink.net>, + pgsql-performance@postgresql.org +Message-ID: <BFAF44F9.14865%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases +Thread-Index: AcXzf2L/4YrM1hDySwKeNGP6hx/XsgABwoDi +In-Reply-To: <6.2.5.6.0.20051127114155.01dbf868@earthlink.net> +MIME-Version: 1.0 +X-OriginalArrivalTime: 27 Nov 2005 19:11:53.0725 (UTC) + FILETIME=[6D7182D0:01C5F386] +X-WSS-ID: 6F94DAE519O4545944-04-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.253 required=5 tests=[AWL=0.000, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.253 +X-Spam-Level: * +X-Archive-Number: 200511/531 +X-Sequence-Number: 15788 + +Ron, + +On 11/27/05 9:10 AM, "Ron" <rjpeace@earthlink.net> wrote: + +> Clever use of RAM can get a 5TB sequential scan down to ~17mins. +> +> Yes, it's a lot of data. But sequential scan times should be in the +> mins or low single digit hours, not days. Particularly if you use +> RAM to maximum advantage. + +Unfortunately, RAM doesn't help with scanning from disk at all. + +WRT using network interfaces to help - it's interesting, but I think what +you'd want to connect to is other machines with storage on them. + +- Luke + + + +From pgsql-performance-owner@postgresql.org Sun Nov 27 15:38:12 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 30C27DC55A + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 15:38:11 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14918-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 15:38:10 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by svr1.postgresql.org (Postfix) with ESMTP id 6A537DBFCF + for <pgsql-performance@postgresql.org>; + Sun, 27 Nov 2005 15:38:08 -0400 (AST) +Received: from 172.16.1.110 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Sun, 27 Nov 2005 14:37:47 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.160]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Sun, 27 Nov + 2005 14:31:25 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.106]) with Microsoft Exchange Server HTTP-DAV ; Sun, 27 Nov + 2005 19:31:24 +0000 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Sun, 27 Nov 2005 11:31:24 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Stephan Szabo" <sszabo@megazone.bigpanda.com>, + "Postgresql Performance" <pgsql-performance@postgresql.org>, + "David Lang" <dlang@invendra.net> +Message-ID: <BFAF498C.14869%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXzafwD25Gxo/A9SmmAhK9e/JqThQAHyr5r +In-Reply-To: <20051127072933.Q62040@megazone.bigpanda.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 27 Nov 2005 19:31:25.0030 (UTC) + FILETIME=[27987860:01C5F389] +X-WSS-ID: 6F94D4802UO6565240-09-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.253 required=5 tests=[AWL=0.000, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.253 +X-Spam-Level: * +X-Archive-Number: 200511/532 +X-Sequence-Number: 15789 + +Stephan, + +On 11/27/05 7:48 AM, "Stephan Szabo" <sszabo@megazone.bigpanda.com> wrote: + +> On Sun, 27 Nov 2005, Luke Lonergan wrote: +> +>> Has anyone done the math.on the original post? 5TB takes how long to +>> scan once? If you want to wait less than a couple of days just for a +>> seq scan, you'd better be in the multi-gb per second range. +> +> Err, I get about 31 megabytes/second to do 5TB in 170,000 seconds. I think +> perhaps you were exaggerating a bit or adding additional overhead not +> obvious from the above. ;) + +Thanks - the calculator on my blackberry was broken ;-) + +> At 1 gigabyte per second, 1 terrabyte should take about 1000 seconds +> (between 16 and 17 minutes). The impressive 3.2 gigabytes per second +> listed before (if it actually scans consistently at that rate), puts it at +> a little over 5 minutes I believe for 1, so about 26 for 5 terrabytes. +> The 200 megabyte per second number puts it about 7 hours for 5 +> terrabytes AFAICS. + +7 hours, days, same thing ;-) + +On the reality of sustained scan rates like that: + +We're getting 2.5GB/s sustained on a 2 year old machine with 16 hosts and 96 +disks. We run them in RAID0, which is only OK because MPP has built-in host +to host mirroring for fault management. + +We just purchased a 4-way cluster with 8 drives each using the 3Ware 9550SX. +Our thought was to try the simplest approach first, which is a single RAID5, +which gets us 7 drives worth of capacity and performance. As I posted +earlier, we get about 400MB/s seq scan rate on the RAID, but the Postgres +8.0 current scan rate limit is 64% of 400MB/s or 256MB/s per host. The 8.1 +mods (thanks Qingqing and Tom!) may increase that significantly toward the +400 max - we've already merged the 8.1 codebase into MPP so we'll also +feature the same enhancements. + +Our next approach is to run these machines in a split RAID0 configuration, +or RAID0 on 4 and 4 drives. We then run an MPP "segment instance" bound to +each CPU and I/O channel. At that point, we'll have all 8 drives of +performance and capacity per host and we should get 333MB/s with current MPP +and perhaps over 400MB/s with MPP/8.1. That would get us up to the 3.2GB/s +for 8 hosts. + +Even better, all operators are executed on all CPUs for each query, so +sorting, hashing, agg, etc etc are run on all CPUs in the cluster. + +- Luke + + + +From pgsql-performance-owner@postgresql.org Sun Nov 27 16:25:44 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 4166FD9F77 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 16:25:43 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 18929-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 16:25:42 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtpauth10.mail.atl.earthlink.net + (smtpauth10.mail.atl.earthlink.net [209.86.89.70]) + by svr1.postgresql.org (Postfix) with ESMTP id 914DCD7EF9 + for <pgsql-performance@postgresql.org>; + Sun, 27 Nov 2005 16:25:40 -0400 (AST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; + d=earthlink.net; + b=eabyL8b5qSo80nUKJpwT+1jxZOz4+ckPRy/D82BfvNL7PZxzeoDpINvq/frw7H1J; + h=Received:Message-Id:X-Mailer:Date:To:From:Subject:In-Reply-To:References:Mime-Version:Content-Type:X-ELNK-Trace:X-Originating-IP; +Received: from [70.22.193.119] (helo=ron-6d52adff2a6.earthlink.net) + by smtpauth10.mail.atl.earthlink.net with asmtp (Exim 4.34) + id 1EgT5h-0004oA-0n; Sun, 27 Nov 2005 15:25:41 -0500 +Message-Id: <6.2.5.6.0.20051127150022.03880848@earthlink.net> +X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6 +Date: Sun, 27 Nov 2005 15:25:36 -0500 +To: "Luke Lonergan" <llonergan@greenplum.com>, + pgsql-performance@postgresql.org +From: Ron <rjpeace@earthlink.net> +Subject: Re: Hardware/OS recommendations for large databases +In-Reply-To: <BFAF44F9.14865%llonergan@greenplum.com> +References: <6.2.5.6.0.20051127114155.01dbf868@earthlink.net> + <BFAF44F9.14865%llonergan@greenplum.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset="us-ascii"; format=flowed +X-ELNK-Trace: + acd68a6551193be5d780f4a490ca69563f9fea00a6dd62bc1c93f0902af1e3d2146ea26d907e6145350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c +X-Originating-IP: 70.22.193.119 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.359 required=5 tests=[AWL=-0.120, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.359 +X-Spam-Level: +X-Archive-Number: 200511/533 +X-Sequence-Number: 15790 + +At 02:11 PM 11/27/2005, Luke Lonergan wrote: +>Ron, +> +>On 11/27/05 9:10 AM, "Ron" <rjpeace@earthlink.net> wrote: +> +> > Clever use of RAM can get a 5TB sequential scan down to ~17mins. +> > +> > Yes, it's a lot of data. But sequential scan times should be in the +> > mins or low single digit hours, not days. Particularly if you use +> > RAM to maximum advantage. +> +>Unfortunately, RAM doesn't help with scanning from disk at all. +I agree with you if you are scanning a table "cold", having never +loaded it before, or if the system is not (or can't be) set up +properly with appropriate buffers. + +However, outside of those 2 cases there are often tricks you can use +with enough RAM (and no, you don't need RAM equal to the size of the +item(s) being scanned) to substantially speed things up. Best case, +you can get performance approximately equal to that of a RAM resident scan. + + +>WRT using network interfaces to help - it's interesting, but I think what +>you'd want to connect to is other machines with storage on them. +Maybe. Or maybe you want to concentrate your storage in a farm that +is connected by network or Fiber Channel to the rest of your +HW. That's what a NAS or SAN is after all. + +"The rest of your HW" nowadays is often a cluster of RAM rich +hosts. Assuming 64GB per host, 5TB can be split across ~79 hosts if +you want to make it all RAM resident. + +Most don't have that kind of budget, but thankfully it is not usually +necessary to make all of the data RAM resident in order to obtain if +not all of the performance benefits you'd get if all of the data was. + +Ron + + + +From pgsql-performance-owner@postgresql.org Sun Nov 27 20:07:32 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by svr1.postgresql.org (Postfix) with ESMTP id 24052DBE8A + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 20:07:32 -0400 (AST) +Received: from svr1.postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 54079-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Sun, 27 Nov 2005 20:07:33 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from megazone.bigpanda.com (megazone.bigpanda.com [64.147.171.210]) + by svr1.postgresql.org (Postfix) with ESMTP id 7F68EDBE5D + for <pgsql-performance@postgresql.org>; + Sun, 27 Nov 2005 20:07:28 -0400 (AST) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id 1E0DF3514F; Sun, 27 Nov 2005 16:07:32 -0800 (PST) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id 1C6083513F; Sun, 27 Nov 2005 16:07:32 -0800 (PST) +Date: Sun, 27 Nov 2005 16:07:32 -0800 (PST) +From: Stephan Szabo <sszabo@megazone.bigpanda.com> +To: Luke Lonergan <llonergan@greenplum.com> +Cc: Postgresql Performance <pgsql-performance@postgresql.org>, + David Lang <dlang@invendra.net> +Subject: Re: Hardware/OS recommendations for large databases ( +In-Reply-To: <BFAF498C.14869%llonergan@greenplum.com> +Message-ID: <20051127160216.V96828@megazone.bigpanda.com> +References: <BFAF498C.14869%llonergan@greenplum.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/535 +X-Sequence-Number: 15792 + + +On Sun, 27 Nov 2005, Luke Lonergan wrote: + +> Stephan, +> +> On 11/27/05 7:48 AM, "Stephan Szabo" <sszabo@megazone.bigpanda.com> wrote: +> +> > On Sun, 27 Nov 2005, Luke Lonergan wrote: +> > +> >> Has anyone done the math.on the original post? 5TB takes how long to +> >> scan once? If you want to wait less than a couple of days just for a +> >> seq scan, you'd better be in the multi-gb per second range. +> > +> > Err, I get about 31 megabytes/second to do 5TB in 170,000 seconds. I think +> > perhaps you were exaggerating a bit or adding additional overhead not +> > obvious from the above. ;) +> +> Thanks - the calculator on my blackberry was broken ;-) + +Well, it was suspiciously close to a factor of 60 off, which when working +in time could have just been a simple math error. + +> > At 1 gigabyte per second, 1 terrabyte should take about 1000 seconds +> > (between 16 and 17 minutes). The impressive 3.2 gigabytes per second +> > listed before (if it actually scans consistently at that rate), puts it at +> > a little over 5 minutes I believe for 1, so about 26 for 5 terrabytes. +> > The 200 megabyte per second number puts it about 7 hours for 5 +> > terrabytes AFAICS. +> +> 7 hours, days, same thing ;-) +> +> On the reality of sustained scan rates like that: + +Well, the reason I asked was that IIRC the 3.2 used earlier in the +discussion was exactly multiplying scanners and base rate (ie, no +additional overhead). I couldn't tell if that was back of the envelope or +if the overhead was in fact negligible. (Or I could be misremembering the +conversation). I don't doubt that it's possible to get the rate, just +wasn't sure if the rate was actually applicable to the ongoing discussion +of the comparison. + +From pgsql-performance-owner@postgresql.org Tue Nov 29 01:50:25 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id BF6D79DCAB3 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 29 Nov 2005 01:50:24 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14214-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 29 Nov 2005 01:50:23 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.invendra.net (sbx-01.invendra.net [66.139.76.16]) + by postgresql.org (Postfix) with ESMTP id E51839DCAB2 + for <pgsql-performance@postgresql.org>; + Tue, 29 Nov 2005 01:50:21 -0400 (AST) +Received: from david.lang.hm (dsl081-044-215.lax1.dsl.speakeasy.net + [64.81.44.215]) + by mail.invendra.net (Postfix) with ESMTP id 8C6E71AC3E9; + Mon, 28 Nov 2005 19:09:26 -0800 (PST) +Date: Sun, 27 Nov 2005 19:09:04 -0800 (PST) +From: David Lang <dlang@invendra.net> +X-X-Sender: dlang@david.lang.hm +To: Brendan Duddridge <brendan@clickspace.com> +Cc: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +In-Reply-To: <179B5137-F0BB-4037-A5AD-3459B914E580@clickspace.com> +Message-ID: <Pine.LNX.4.62.0511271903180.2807@qnivq.ynat.uz> +References: <BFB0BF1B.1495C%llonergan@greenplum.com> + <179B5137-F0BB-4037-A5AD-3459B914E580@clickspace.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.78 required=5 tests=[AWL=-0.025, + DATE_IN_PAST_24_48=0.805] +X-Spam-Score: 0.78 +X-Spam-Level: +X-Archive-Number: 200511/549 +X-Sequence-Number: 15806 + +On Mon, 28 Nov 2005, Brendan Duddridge wrote: + +> Forgive my ignorance, but what is MPP? Is that part of Bizgres? Is it +> possible to upgrade from Postgres 8.1 to Bizgres? + +MPP is the Greenplum propriatary extention to postgres that spreads the +data over multiple machines, (raid, but with entire machines not just +drives, complete with data replication within the cluster to survive a +machine failing) + +for some types of queries they can definantly scale lineraly with the +number of machines (other queries are far more difficult and the overhead +of coordinating the machines shows more. this is one of the key things +that the new version they recently announced the beta for is supposed to +be drasticly improving) + +early in the year when I first looked at them their prices were +exorbadent, but Luke says I'm wildly mistake on their current prices so +call them for details + +it uses the same interfaces as postgres so it should be a drop in +replacement to replace a single server with a cluster. + +it's facinating technology to read about. + +I seem to remember reading that one of the other postgres companies is +also producing a clustered version of postgres, but I don't remember who +and know nothing about them. + +David Lang + +From pgsql-performance-owner@postgresql.org Tue Nov 29 01:48:36 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 7E10D9DCD39 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 29 Nov 2005 01:48:27 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 12644-03-11 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 29 Nov 2005 01:48:25 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.invendra.net (sbx-01.invendra.net [66.139.76.16]) + by postgresql.org (Postfix) with ESMTP id CBC9B9DCA9F + for <pgsql-performance@postgresql.org>; + Tue, 29 Nov 2005 01:17:03 -0400 (AST) +Received: from david.lang.hm (dsl081-044-215.lax1.dsl.speakeasy.net + [64.81.44.215]) + by mail.invendra.net (Postfix) with ESMTP id BBC3C1AC3EA; + Mon, 28 Nov 2005 20:01:27 -0800 (PST) +Date: Sun, 27 Nov 2005 20:01:05 -0800 (PST) +From: David Lang <dlang@invendra.net> +X-X-Sender: dlang@david.lang.hm +To: Brendan Duddridge <brendan@clickspace.com> +Cc: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +In-Reply-To: <3017A204-1BAF-4E62-ADA6-695E34557645@clickspace.com> +Message-ID: <Pine.LNX.4.62.0511271940400.2807@qnivq.ynat.uz> +References: <BFB0BF1B.1495C%llonergan@greenplum.com> + <179B5137-F0BB-4037-A5AD-3459B914E580@clickspace.com> + <Pine.LNX.4.62.0511271903180.2807@qnivq.ynat.uz> + <3017A204-1BAF-4E62-ADA6-695E34557645@clickspace.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.776 required=5 tests=[AWL=-0.030, + DATE_IN_PAST_24_48=0.805] +X-Spam-Score: 0.776 +X-Spam-Level: +X-Archive-Number: 200511/548 +X-Sequence-Number: 15805 + +On Mon, 28 Nov 2005, Brendan Duddridge wrote: + +> Hi David, +> +> Thanks for your reply. So how is that different than something like Slony2 or +> pgcluster with multi-master replication? Is it similar technology? We're +> currently looking for a good clustering solution that will work on our Apple +> Xserves and Xserve RAIDs. + +MPP doesn't just split up the data, it splits up the processing as well, +so if you have a 5 machine cluster, each machine holds 1/5 of your data +(plus a backup for one of the other machines) and when you do a query MPP +slices and dices the query to send a subset of the query to each machine, +it then gets the responses from all the machines and combines them + +if you ahve to do a full table scan for example, wach machine would only +have to go through 20% of the data + +a Slony of pgcluster setup has each machine with a full copy of all the +data, only one machine can work on a given query at a time, and if you +have to do a full table scan one machine needs to read 100% of the data. + +in many ways this is the holy grail of databases. almost all other areas +of computing can now be scaled by throwing more machines at the problem in +a cluster, with each machine just working on it's piece of the problem, +but databases have had serious trouble doing the same and so have been +ruled by the 'big monster machine'. Oracle has been selling Oracle Rac for +a few years, and reports from people who have used it range drasticly +(from it works great, to it's a total disaster), in part depending on the +types of queries that have been made. + +Greenplum thinks that they have licked the problems for the more general +case (and that commodity networks are now fast enough to match disk speeds +in processing the data) if they are right then when they hit full release +with the new version they should be cracking a lot of the +price/performance records on the big database benchmarks (TPC and +similar), and if their pricing is reasonable, they may be breaking them by +an order of magnatude or more (it's not unusual for the top machines to +spend more then $1,000,000 on just their disk arrays for those +systems, MPP could conceivably put togeather a cluster of $5K machines +that runs rings around them (and probably will for at least some of the +subtests, the big question is if they can sweep the board and take the top +spots outright) + +they have more details (and marketing stuff) on their site at +http://www.greenplum.com/prod_deepgreen_cluster.html + +don't get me wrong, I am very impressed with their stuff, but (haveing +ranted a little here on the list about them) I think MPP and it's +performace is a bit off topic for the postgres performance list (at least +until the postgres project itself starts implementing similar features :-) + +David Lang + +> Thanks, +> +> ____________________________________________________________________ +> Brendan Duddridge | CTO | 403-277-5591 x24 | brendan@clickspace.com +> +> ClickSpace Interactive Inc. +> Suite L100, 239 - 10th Ave. SE +> Calgary, AB T2G 0V9 +> +> http://www.clickspace.com +> +> On Nov 27, 2005, at 8:09 PM, David Lang wrote: +> +>> On Mon, 28 Nov 2005, Brendan Duddridge wrote: +>> +>>> Forgive my ignorance, but what is MPP? Is that part of Bizgres? Is it +>>> possible to upgrade from Postgres 8.1 to Bizgres? +>> +>> MPP is the Greenplum propriatary extention to postgres that spreads the +>> data over multiple machines, (raid, but with entire machines not just +>> drives, complete with data replication within the cluster to survive a +>> machine failing) +>> +>> for some types of queries they can definantly scale lineraly with the +>> number of machines (other queries are far more difficult and the overhead +>> of coordinating the machines shows more. this is one of the key things that +>> the new version they recently announced the beta for is supposed to be +>> drasticly improving) +>> +>> early in the year when I first looked at them their prices were exorbadent, +>> but Luke says I'm wildly mistake on their current prices so call them for +>> details +>> +>> it uses the same interfaces as postgres so it should be a drop in +>> replacement to replace a single server with a cluster. +>> +>> it's facinating technology to read about. +>> +>> I seem to remember reading that one of the other postgres companies is also +>> producing a clustered version of postgres, but I don't remember who and +>> know nothing about them. +>> +>> David Lang +>> +> +> + +From pgsql-performance-owner@postgresql.org Mon Nov 28 09:31:02 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id DD08D9DCAB3 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 09:31:01 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 26752-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 09:31:04 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by postgresql.org (Postfix) with ESMTP id 3317D9DCA94 + for <pgsql-performance@postgresql.org>; + Mon, 28 Nov 2005 09:30:58 -0400 (AST) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-MimeOLE: Produced By Microsoft Exchange V6.5 +Subject: Re: Newbie question: ultra fast count(*) +Date: Mon, 28 Nov 2005 08:31:06 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD965@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Newbie question: ultra fast count(*) +Thread-Index: AcX0Hg/Vna54jEGaREyT2R7cZTCHVgAAY40g +From: "Merlin Moncure" <merlin.moncure@rcsonline.com> +To: "Rodrigo Madera" <rodrigo.madera@gmail.com> +Cc: <pgsql-performance@postgresql.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/536 +X-Sequence-Number: 15793 + +> I have been reading all this technical talk about costs and such that +> I don't (_yet_) understand. +>=20 +> Now I'm scared... what's the fastest way to do an equivalent of +> count(*) on a table to know how many items it has? + +Make sure to analyze the database frequently and check pg_class for +reltuples field. This gives 0 time approximations of # row in table at +the time of the last analyze. + +Many other approaches...check archives. Also your requirements are +probably not as high as you think they are ;) + +Merlin + + +From pgsql-performance-owner@postgresql.org Mon Nov 28 12:27:16 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 34BEA9DCBAF + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 12:27:15 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 65197-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 12:27:12 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw04.mi8.com [63.240.6.44]) + by postgresql.org (Postfix) with ESMTP id F26739DCB0B + for <pgsql-performance@postgresql.org>; + Mon, 28 Nov 2005 12:27:11 -0400 (AST) +Received: from 172.16.1.110 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D4)); Mon, 28 Nov 2005 11:26:54 -0500 +X-Server-Uuid: C8FB4D43-1108-484A-A898-3CBCC7906230 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.160]) by + D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Mon, 28 Nov + 2005 11:26:21 -0500 +Received: from 69.181.100.71 ([69.181.100.71]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.106]) with Microsoft Exchange Server HTTP-DAV ; Mon, 28 Nov + 2005 16:26:21 +0000 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Mon, 28 Nov 2005 08:26:21 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: pgsql-performance@postgresql.org +cc: "eng@intranet.greenplum.com" <eng@intranet.greenplum.com> +Message-ID: <BFB06FAD.148EC%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcXvIxdwfLDwWrP8Q669kHxJ85F1twBrF12iABLTyBIAx2zelg== +In-Reply-To: <BFAB355B.1468A%llonergan@greenplum.com> +MIME-Version: 1.0 +X-OriginalArrivalTime: 28 Nov 2005 16:26:21.0905 (UTC) + FILETIME=[7807CC10:01C5F438] +X-WSS-ID: 6F95F0402UO7731728-01-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.253 required=5 tests=[AWL=0.000, + RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.253 +X-Spam-Level: * +X-Archive-Number: 200511/537 +X-Sequence-Number: 15794 + +The MPP test I ran was with the release version 2.0 of MPP which is based on +Postgres 8.0, the upcoming 2.1 release is based on 8.1, and 8.1 is far +faster at seq scan + agg. 12,937MB were counted in 4.5 seconds, or 2890MB/s +from I/O cache. That's 722MB/s per host, and 360MB/s per Postgres instance, +up from 267 previously with 8.0.3. + +I'm going to apply Tom's pre-8.2 seq scan locking optimization and see how +much better we can get! + +- Luke + + ========================================================== + Bizgres MPP CVS tip (2.1 pre), 8 data segments, 1 per CPU + ========================================================== + +llonergan=# \timing +Timing is on. +llonergan=# explain select count(1) from lineitem; + QUERY PLAN +-------------------------------------------------------------------------- + Aggregate (cost=0.01..0.01 rows=1 width=0) + -> Gather Motion (cost=0.01..0.01 rows=1 width=0) + -> Aggregate (cost=0.01..0.01 rows=1 width=0) + -> Seq Scan on lineitem (cost=0.00..0.00 rows=1 width=0) +(4 rows) + +Time: 1.464 ms +llonergan=# select count(1) from lineitem; + count +---------- + 59986052 +(1 row) + +Time: 4478.563 ms +llonergan=# select count(1) from lineitem; + count +---------- + 59986052 +(1 row) + +Time: 4550.917 ms +llonergan=# select count(1) from lineitem; + count +---------- + 59986052 +(1 row) + +Time: 4482.261 ms + + +On 11/24/05 9:16 AM, "Luke Lonergan" <LLonergan@greenplum.com> wrote: + +> The same 12.9GB distributed across 4 machines using Bizgres MPP fits into +> I/O cache. The interesting result is that the query "select count(1)" is +> limited in speed to 280 MB/s per CPU when run on the lineitem table. So +> when I run it spread over 4 machines, one CPU per machine I get this: +> +> ====================================================== +> Bizgres MPP, 4 data segments, 1 per 2 CPUs +> ====================================================== +> llonergan=# explain select count(1) from lineitem; +> QUERY PLAN +> ---------------------------------------------------------------------------- +> ---------- +> Aggregate (cost=582452.00..582452.00 rows=1 width=0) +> -> Gather Motion (cost=582452.00..582452.00 rows=1 width=0) +> -> Aggregate (cost=582452.00..582452.00 rows=1 width=0) +> -> Seq Scan on lineitem (cost=0.00..544945.00 rows=15002800 +> width=0) +> (4 rows) +> +> llonergan=# \timing +> Timing is on. +> llonergan=# select count(1) from lineitem; +> count +> ---------- +> 59986052 +> (1 row) +> +> Time: 12191.435 ms +> llonergan=# select count(1) from lineitem; +> count +> ---------- +> 59986052 +> (1 row) +> +> Time: 11986.109 ms +> llonergan=# select count(1) from lineitem; +> count +> ---------- +> 59986052 +> (1 row) +> +> Time: 11448.941 ms +> ====================================================== +> +> That's 12,937 MB in 11.45 seconds, or 1,130 MB/s. When you divide out the +> number of Postgres instances (4), that's 283MB/s per Postgres instance. +> +> To verify that this has nothing to do with MPP, I ran it in a special +> internal mode on one instance and got the same result. +> +> So - we should be able to double this rate by running one segment per CPU, +> or two per host: +> +> ====================================================== +> Bizgres MPP, 8 data segments, 1 per CPU +> ====================================================== +> llonergan=# select count(1) from lineitem; +> count +> ---------- +> 59986052 +> (1 row) +> +> Time: 6484.594 ms +> llonergan=# select count(1) from lineitem; +> count +> ---------- +> 59986052 +> (1 row) +> +> Time: 6156.729 ms +> llonergan=# select count(1) from lineitem; +> count +> ---------- +> 59986052 +> (1 row) +> +> Time: 6063.416 ms +> ====================================================== +> That's 12,937 MB in 11.45 seconds, or 2,134 MB/s. When you divide out the +> number of Postgres instances (8), that's 267MB/s per Postgres instance. +> +> So, if you want to "select count(1)", using more CPUs is a good idea! For +> most complex queries, having lots of CPUs + MPP is a good combo. +> +> Here is an example of a sorting plan - this should probably be done with a +> hash aggregation, but using 8 CPUs makes it go 8x faster: +> +> ====================================================== +> Bizgres MPP, 8 data segments, 1 per CPU +> ====================================================== +> llonergan=# \timing +> Timing is on. +> llonergan=# explain select l_orderkey from lineitem order by l_shipdate, +> l_extendedprice limit 10; +> QUERY PLAN +> ---------------------------------------------------------------------------- +> ----- +> Limit (cost=0.01..0.02 rows=1 width=24) +> -> Gather Motion (cost=0.01..0.02 rows=1 width=24) +> Merge Key: l_shipdate, l_extendedprice +> -> Limit (cost=0.01..0.02 rows=1 width=24) +> -> Sort (cost=0.01..0.02 rows=1 width=24) +> Sort Key: l_shipdate, l_extendedprice +> -> Seq Scan on lineitem (cost=0.00..0.00 rows=1 +> width=24) +> (7 rows) +> +> Time: 0.592 ms +> llonergan=# select l_orderkey from lineitem order by l_shipdate, +> l_extendedprice limit 10; +> l_orderkey +> ------------ +> 51829667 +> 26601603 +> 16579717 +> 40046023 +> 41707078 +> 22880928 +> 35584422 +> 31272229 +> 49914018 +> 42309990 +> (10 rows) +> +> Time: 93469.443 ms +> +> ====================================================== +> +> So that's 60M rows and 12.9GB sorted in 93.5 seconds. +> +> - Luke +> +> + + + + +From pgsql-performance-owner@postgresql.org Mon Nov 28 14:10:10 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id D4F739DCAD6 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 14:10:08 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 78685-08 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 14:10:07 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by postgresql.org (Postfix) with ESMTP id 36CD29DCAB7 + for <pgsql-performance@postgresql.org>; + Mon, 28 Nov 2005 14:10:03 -0400 (AST) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-MimeOLE: Produced By Microsoft Exchange V6.5 +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Mon, 28 Nov 2005 13:10:07 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD97C@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases ( +Thread-Index: AcX0Har25nxnYObrS3+XepwMdgqpDgAKRLww +From: "Merlin Moncure" <merlin.moncure@rcsonline.com> +To: "Mark Kirkwood" <markir@paradise.net.nz> +Cc: <pgsql-performance@postgresql.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/538 +X-Sequence-Number: 15795 + +>=20 +> It certainly makes quite a difference as I measure it: +>=20 +> doing select(1) from a 181000 page table (completely uncached) on my +PIII: +>=20 +> 8.0 : 32 s +> 8.1 : 25 s +>=20 +> Note that the 'fastcount()' function takes 21 s in both cases - so all +> the improvement seems to be from the count overhead reduction. + +Are you running windows? There is a big performance improvement in +count(*) on pg 8.0->8.1 on win32 that is not relevant to this debate... + +Merlin + +From pgsql-performance-owner@postgresql.org Mon Nov 28 17:45:55 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 4501C9DCC34 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 17:45:52 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 54723-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 17:45:52 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from linda-2.paradise.net.nz (bm-2a.paradise.net.nz + [203.96.152.181]) + by postgresql.org (Postfix) with ESMTP id 7856E9DCC2A + for <pgsql-performance@postgresql.org>; + Mon, 28 Nov 2005 17:45:49 -0400 (AST) +Received: from smtp-1.paradise.net.nz + (tclsnelb1-src-1.paradise.net.nz [203.96.152.172]) by + linda-2.paradise.net.nz (Paradise.net.nz) with ESMTP id + <0IQO00G8VPSBIV@linda-2.paradise.net.nz> for + pgsql-performance@postgresql.org; Tue, 29 Nov 2005 10:45:47 +1300 (NZDT) +Received: from [192.168.1.11] (218-101-29-74.dsl.clear.net.nz [218.101.29.74]) + by smtp-1.paradise.net.nz (Postfix) with ESMTP id 49B63146C748; Tue, + 29 Nov 2005 10:45:47 +1300 (NZDT) +Date: Tue, 29 Nov 2005 10:45:46 +1300 +From: Mark Kirkwood <markir@paradise.net.nz> +Subject: Re: Hardware/OS recommendations for large databases ( +In-reply-to: <6EE64EF3AB31D5448D0007DD34EEB3417DD97C@Herge.rcsinc.local> +To: Merlin Moncure <merlin.moncure@rcsonline.com> +Cc: pgsql-performance@postgresql.org +Message-id: <438B7A8A.4020505@paradise.net.nz> +MIME-version: 1.0 +Content-type: text/plain; format=flowed; charset=ISO-8859-1 +Content-transfer-encoding: 7bit +X-Accept-Language: en-us, en +User-Agent: Mozilla Thunderbird 1.0.6 (X11/20051106) +References: <6EE64EF3AB31D5448D0007DD34EEB3417DD97C@Herge.rcsinc.local> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/539 +X-Sequence-Number: 15796 + +Merlin Moncure wrote: +>>It certainly makes quite a difference as I measure it: +>> +>>doing select(1) from a 181000 page table (completely uncached) on my +> +> PIII: +> +>>8.0 : 32 s +>>8.1 : 25 s +>> +>>Note that the 'fastcount()' function takes 21 s in both cases - so all +>>the improvement seems to be from the count overhead reduction. +> +> +> Are you running windows? There is a big performance improvement in +> count(*) on pg 8.0->8.1 on win32 that is not relevant to this debate... +> + +No - FreeBSD 6.0 on a dual PIII 1 Ghz. The slow cpu means that the 8.1 +improvements are very noticeable! + +A point of interest - applying Niels palloc - avoiding changes to +NodeAgg.c and int8.c in 8.0 changes those results to: + +8.0 + palloc avoiding patch : 27 s + +(I am guessing the remaining 2 s could be shaved off if I backported +8.1's virtual tuples - however that looked like a lot of work) + +Cheers + +Mark + +From pgsql-performance-owner@postgresql.org Mon Nov 28 18:07:44 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 6A4D39DCC0C + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 18:07:42 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 60594-01 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 18:07:42 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.mi8.com (d01gw02.mi8.com [63.240.6.46]) + by postgresql.org (Postfix) with ESMTP id 483D19DCAB7 + for <pgsql-performance@postgresql.org>; + Mon, 28 Nov 2005 18:07:38 -0400 (AST) +Received: from 172.16.1.112 by mail.mi8.com with ESMTP (- Welcome to Mi8 + Corporation www.Mi8.com (D2)); Mon, 28 Nov 2005 17:07:26 -0500 +X-Server-Uuid: 7829E76E-BB9E-4995-8473-3C0929DF7DD1 +Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.160]) by + D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Mon, 28 Nov + 2005 17:06:59 -0500 +Received: from 67.103.45.218 ([67.103.45.218]) by MI8NYCMAIL06.Mi8.com ( + [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( + [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Mon, 28 Nov + 2005 22:05:14 +0000 +User-Agent: Microsoft-Entourage/11.2.1.051004 +Date: Mon, 28 Nov 2005 14:05:15 -0800 +Subject: Re: Hardware/OS recommendations for large databases ( +From: "Luke Lonergan" <llonergan@greenplum.com> +To: "Mark Kirkwood" <markir@paradise.net.nz>, + "Merlin Moncure" <merlin.moncure@rcsonline.com> +cc: pgsql-performance@postgresql.org +Message-ID: <BFB0BF1B.1495C%llonergan@greenplum.com> +Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases + ( +Thread-Index: AcX0ZjyyJ8+6opcfSNKK6fecsFUZHgAAZLNv +In-Reply-To: <438B7A8A.4020505@paradise.net.nz> +MIME-Version: 1.0 +X-OriginalArrivalTime: 28 Nov 2005 22:06:59.0885 (UTC) + FILETIME=[0E040DD0:01C5F468] +X-WSS-ID: 6F95A1DA4J81252576-94-01 +Content-Type: text/plain; + charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=1.253 required=5 tests=[RCVD_NUMERIC_HELO=1.253] +X-Spam-Score: 1.253 +X-Spam-Level: * +X-Archive-Number: 200511/540 +X-Sequence-Number: 15797 + +Mark, + +On 11/28/05 1:45 PM, "Mark Kirkwood" <markir@paradise.net.nz> wrote: + +>>> 8.0 : 32 s +>>> 8.1 : 25 s + +A 22% reduction. + +select count(1) on 12,900MB = 1617125 pages fully cached: + +MPP based on 8.0 : 6.06s +MPP based on 8.1 : 4.45s + +A 26% reduction. + +I'll take it! + +I am looking to back-port Tom's pre-8.2 changes and test again, maybe +tonight. + +- Luke + + + +From pgsql-performance-owner@postgresql.org Mon Nov 28 19:45:22 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id B0E739DCC0C + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 19:45:21 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 12328-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 19:44:44 -0400 (AST) +X-Greylist: delayed 00:25:15.507181 by SQLgrey- +Received: from cobalt.clickspace.com (mail.clickspace.com [65.110.166.234]) + by postgresql.org (Postfix) with ESMTP id 755FD9DCC42 + for <pgsql-performance@postgresql.org>; + Mon, 28 Nov 2005 19:44:39 -0400 (AST) +Received: from [192.168.5.172] ([68.145.108.192]) + by cobalt.clickspace.com (8.10.2/8.10.2) with ESMTP id jASNJMK21320 + for <pgsql-performance@postgresql.org>; Mon, 28 Nov 2005 16:19:22 -0700 +Mime-Version: 1.0 (Apple Message framework v746.2) +In-Reply-To: <BFB0BF1B.1495C%llonergan@greenplum.com> +References: <BFB0BF1B.1495C%llonergan@greenplum.com> +Content-Type: multipart/signed; micalg=sha1; boundary=Apple-Mail-1-293953008; + protocol="application/pkcs7-signature" +Message-Id: <179B5137-F0BB-4037-A5AD-3459B914E580@clickspace.com> +From: Brendan Duddridge <brendan@clickspace.com> +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Mon, 28 Nov 2005 16:19:34 -0700 +To: pgsql-performance@postgresql.org +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/542 +X-Sequence-Number: 15799 + + +--Apple-Mail-1-293953008 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; + charset=US-ASCII; + delsp=yes; + format=flowed + +Forgive my ignorance, but what is MPP? Is that part of Bizgres? Is it +possible to upgrade from Postgres 8.1 to Bizgres? + +Thanks, + +____________________________________________________________________ +Brendan Duddridge | CTO | 403-277-5591 x24 | brendan@clickspace.com + +ClickSpace Interactive Inc. +Suite L100, 239 - 10th Ave. SE +Calgary, AB T2G 0V9 + +http://www.clickspace.com + +On Nov 28, 2005, at 3:05 PM, Luke Lonergan wrote: + +> Mark, +> +> On 11/28/05 1:45 PM, "Mark Kirkwood" <markir@paradise.net.nz> wrote: +> +>>>> 8.0 : 32 s +>>>> 8.1 : 25 s +> +> A 22% reduction. +> +> select count(1) on 12,900MB = 1617125 pages fully cached: +> +> MPP based on 8.0 : 6.06s +> MPP based on 8.1 : 4.45s +> +> A 26% reduction. +> +> I'll take it! +> +> I am looking to back-port Tom's pre-8.2 changes and test again, maybe +> tonight. +> +> - Luke +> +> +> +> ---------------------------(end of +> broadcast)--------------------------- +> TIP 5: don't forget to increase your free space map settings +> + + +--Apple-Mail-1-293953008 +Content-Transfer-Encoding: base64 +Content-Type: application/pkcs7-signature; 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+ Mon, 28 Nov 2005 19:37:51 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 73445-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 19:37:14 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from relais.videotron.ca (relais.videotron.ca [24.201.245.36]) + by postgresql.org (Postfix) with ESMTP id A56989DCAB2 + for <pgsql-performance@postgresql.org>; + Mon, 28 Nov 2005 19:37:10 -0400 (AST) +Received: from [192.168.1.100] ([24.202.23.128]) by + VL-MO-MR002.ip.videotron.ca + (Sun Java System Messaging Server 6.2-2.05 (built Apr 28 2005)) + with ESMTP id <0IQO009M1UY0MRC0@VL-MO-MR002.ip.videotron.ca> for + pgsql-performance@postgresql.org; Mon, 28 Nov 2005 18:37:13 -0500 (EST) +Date: Mon, 28 Nov 2005 18:40:59 -0500 +From: David Gagnon <dgagnon@siunik.com> +Subject: Please help with this explain analyse... +To: pgsql-performance@postgresql.org +Message-id: <438B958B.3010602@siunik.com> +MIME-version: 1.0 +Content-type: text/plain; charset=ISO-8859-1; format=flowed +Content-transfer-encoding: 7BIT +X-Accept-Language: en-us, en +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.343 required=5 tests=[AWL=0.343] +X-Spam-Score: 0.343 +X-Spam-Level: +X-Archive-Number: 200511/541 +X-Sequence-Number: 15798 + +Hi all, + + I don't understand why this request take so long. Maybe I read the +analyse correctly but It seem that the first line(Nested Loop Left Join +...) take all the time. But I don't understand where the performance +problem is ??? All the time is passed in the first line ... + +Thanks for your help! + +/David + + +explain analyse SELECT * + + FROM CR INNER JOIN CS ON CR.CRNUM = CS.CSCRNUM AND +CR.CRYPNUM = CS.CSYPNUM + INNER JOIN GL ON CS.CSGLNUM = GL.GLNUM AND +GL.GLSOCTRL = 1 + INNER JOIN RR ON CR.CRRRNUM = RR.RRNUM + LEFT OUTER JOIN YR ON YR.YRYOTYPE = 'Client' AND +YR.YRYONUM = 'Comptabilite.Recevable.Regroupement' AND YR.YRREF = RR.RRNUM + WHERE CRYPNUM = 'M' + AND CRDATE + INTERVAL '0 days' <= '2005-01-28' + + +"Nested Loop Left Join (cost=0.00..42.12 rows=1 width=8143) (actual +time=15.254..200198.524 rows=8335 loops=1)" +" Join Filter: (("inner".yrref)::text = ("outer".rrnum)::text)" +" -> Nested Loop (cost=0.00..36.12 rows=1 width=7217) (actual +time=0.441..2719.821 rows=8335 loops=1)" +" -> Nested Loop (cost=0.00..30.12 rows=1 width=1580) (actual +time=0.242..1837.413 rows=8335 loops=1)" +" -> Nested Loop (cost=0.00..18.07 rows=2 width=752) +(actual time=0.145..548.607 rows=13587 loops=1)" +" -> Seq Scan on gl (cost=0.00..5.21 rows=1 +width=608) (actual time=0.036..0.617 rows=1 loops=1)" +" Filter: (glsoctrl = 1)" +" -> Index Scan using cs_pk on cs (cost=0.00..12.83 +rows=2 width=144) (actual time=0.087..444.999 rows=13587 loops=1)" +" Index Cond: (('M'::text = (cs.csypnum)::text) +AND ((cs.csglnum)::text = ("outer".glnum)::text))" +" -> Index Scan using cr_pk on cr (cost=0.00..6.02 rows=1 +width=828) (actual time=0.073..0.077 rows=1 loops=13587)" +" Index Cond: (((cr.crypnum)::text = 'M'::text) AND +(cr.crnum = "outer".cscrnum))" +" Filter: ((crdate + '00:00:00'::interval) <= +'2005-01-28 00:00:00'::timestamp without time zone)" +" -> Index Scan using rr_pk on rr (cost=0.00..5.99 rows=1 +width=5637) (actual time=0.062..0.069 rows=1 loops=8335)" +" Index Cond: (("outer".crrrnum)::text = (rr.rrnum)::text)" +" -> Index Scan using yr_idx1 on yr (cost=0.00..5.99 rows=1 +width=926) (actual time=0.127..17.379 rows=1154 loops=8335)" +" Index Cond: (((yryotype)::text = 'Client'::text) AND +((yryonum)::text = 'Comptabilite.Recevable.Regroupement'::text))" +"Total runtime: 200235.732 ms" + + +From pgsql-performance-owner@postgresql.org Mon Nov 28 19:47:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 86F7A9DCC43 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 19:47:48 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 72619-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 19:47:12 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from presinet.com (presinet.com [209.53.156.1]) + by postgresql.org (Postfix) with ESMTP id BE2319DCC33 + for <pgsql-performance@postgresql.org>; + Mon, 28 Nov 2005 19:47:07 -0400 (AST) +Received: from [10.10.1.151] ([10.10.1.151]) by presinet.com with Microsoft + SMTPSVC(6.0.3790.1830); Mon, 28 Nov 2005 15:44:25 -0800 +Message-ID: <438B96C6.4090902@PresiNET.com> +Date: Mon, 28 Nov 2005 15:46:14 -0800 +From: Bricklen Anderson <BAnderson@PresiNET.com> +User-Agent: Debian Thunderbird 1.0.7 (X11/20051017) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: David Gagnon <dgagnon@siunik.com> +CC: pgsql-performance@postgresql.org +Subject: Re: Please help with this explain analyse... +References: <438B958B.3010602@siunik.com> +In-Reply-To: <438B958B.3010602@siunik.com> +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: 7bit +X-OriginalArrivalTime: 28 Nov 2005 23:44:25.0750 (UTC) + FILETIME=[AA6C4360:01C5F475] +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/543 +X-Sequence-Number: 15800 + +David Gagnon wrote: + +> " -> Index Scan using cr_pk on cr (cost=0.00..6.02 rows=1 +> width=828) (actual time=0.073..0.077 rows=1 loops=13587)" +> " Index Cond: (((cr.crypnum)::text = 'M'::text) AND +> (cr.crnum = "outer".cscrnum))" +> " Filter: ((crdate + '00:00:00'::interval) <= +> '2005-01-28 00:00:00'::timestamp without time zone)" +> " -> Index Scan using rr_pk on rr (cost=0.00..5.99 rows=1 +> width=5637) (actual time=0.062..0.069 rows=1 loops=8335)" +> " Index Cond: (("outer".crrrnum)::text = (rr.rrnum)::text)" +> " -> Index Scan using yr_idx1 on yr (cost=0.00..5.99 rows=1 +> width=926) (actual time=0.127..17.379 rows=1154 loops=8335)" + +Your loops are what is causing the time spent. +eg. "actual time=0.127..17.379 rows=1154 loops=8335)" == +8335*(17.379-0.127)/1000=>143 secs (if my math is correct). + + + +-- +_______________________________ + +This e-mail may be privileged and/or confidential, and the sender does +not waive any related rights and obligations. Any distribution, use or +copying of this e-mail or the information it contains by other than an +intended recipient is unauthorized. If you received this e-mail in +error, please advise me (by return e-mail or otherwise) immediately. +_______________________________ + +From pgsql-performance-owner@postgresql.org Mon Nov 28 20:01:09 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 6D48A9DCC42 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 20:01:08 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 72712-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 20:00:32 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by postgresql.org (Postfix) with ESMTP id A4F439DCC57 + for <pgsql-performance@postgresql.org>; + Mon, 28 Nov 2005 20:00:27 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAT00U6S017299; + Mon, 28 Nov 2005 19:00:30 -0500 (EST) +To: Bricklen Anderson <BAnderson@PresiNET.com> +cc: David Gagnon <dgagnon@siunik.com>, pgsql-performance@postgresql.org +Subject: Re: Please help with this explain analyse... +In-reply-to: <438B96C6.4090902@PresiNET.com> +References: <438B958B.3010602@siunik.com> <438B96C6.4090902@PresiNET.com> +Comments: In-reply-to Bricklen Anderson <BAnderson@PresiNET.com> + message dated "Mon, 28 Nov 2005 15:46:14 -0800" +Date: Mon, 28 Nov 2005 19:00:30 -0500 +Message-ID: <17298.1133222430@sss.pgh.pa.us> +From: Tom Lane <tgl@sss.pgh.pa.us> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.004 required=5 tests=[AWL=0.004] +X-Spam-Score: 0.004 +X-Spam-Level: +X-Archive-Number: 200511/544 +X-Sequence-Number: 15801 + +Bricklen Anderson <BAnderson@PresiNET.com> writes: +> Your loops are what is causing the time spent. +> eg. "actual time=0.127..17.379 rows=1154 loops=8335)" == +> 8335*(17.379-0.127)/1000=>143 secs (if my math is correct). + +As for where the problem is, I think it's the horrid misestimate of the +number of matching rows in cs_pk: + +>> " -> Index Scan using cs_pk on cs (cost=0.00..12.83 +>> rows=2 width=144) (actual time=0.087..444.999 rows=13587 loops=1)" +>> " Index Cond: (('M'::text = (cs.csypnum)::text) +>> AND ((cs.csglnum)::text = ("outer".glnum)::text))" + +Has that table been ANALYZEd recently? How about the gl table? + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Mon Nov 28 22:13:07 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 78D159DCB0C + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 22:13:06 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 92272-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 22:13:09 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from relais.videotron.ca (relais.videotron.ca [24.201.245.36]) + by postgresql.org (Postfix) with ESMTP id 68A7C9DCAB3 + for <pgsql-performance@postgresql.org>; + Mon, 28 Nov 2005 22:13:02 -0400 (AST) +Received: from [192.168.1.100] ([24.202.23.128]) by + VL-MO-MR004.ip.videotron.ca + (Sun Java System Messaging Server 6.2-2.05 (built Apr 28 2005)) + with ESMTP id <0IQP004MG25U4XB0@VL-MO-MR004.ip.videotron.ca> for + pgsql-performance@postgresql.org; Mon, 28 Nov 2005 21:13:07 -0500 (EST) +Date: Mon, 28 Nov 2005 21:16:52 -0500 +From: David Gagnon <dgagnon@siunik.com> +Subject: Re: Please help with this explain analyse... +In-reply-to: <17298.1133222430@sss.pgh.pa.us> +To: Tom Lane <tgl@sss.pgh.pa.us> +Cc: Bricklen Anderson <BAnderson@PresiNET.com>, + pgsql-performance@postgresql.org +Message-id: <438BBA14.5080103@siunik.com> +MIME-version: 1.0 +Content-type: text/plain; charset=ISO-8859-1; format=flowed +Content-transfer-encoding: 7BIT +X-Accept-Language: en-us, en +References: <438B958B.3010602@siunik.com> <438B96C6.4090902@PresiNET.com> + <17298.1133222430@sss.pgh.pa.us> +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.229 required=5 tests=[AWL=0.229] +X-Spam-Score: 0.229 +X-Spam-Level: +X-Archive-Number: 200511/545 +X-Sequence-Number: 15802 + +I restored my db but haven't run the analyse... That was the problem. + +Thanks +/David + +"Merge Left Join (cost=2273.54..2290.19 rows=228 width=816) (actual +time=2098.257..2444.472 rows=8335 loops=1)" +" Merge Cond: (("outer".rrnum)::text = "inner"."?column8?")" +" -> Merge Join (cost=2131.25..2141.31 rows=228 width=744) (actual +time=2037.953..2251.289 rows=8335 loops=1)" +" Merge Cond: ("outer"."?column31?" = "inner"."?column77?")" +" -> Sort (cost=1975.03..1975.60 rows=228 width=235) (actual +time=1798.556..1811.828 rows=8335 loops=1)" +" Sort Key: (cr.crrrnum)::text" +" -> Hash Join (cost=1451.41..1966.10 rows=228 width=235) +(actual time=267.751..515.396 rows=8335 loops=1)" +" Hash Cond: ("outer".crnum = "inner".cscrnum)" +" -> Seq Scan on cr (cost=0.00..489.77 rows=4529 +width=101) (actual time=0.077..97.615 rows=8335 loops=1)" +" Filter: (((crypnum)::text = 'M'::text) AND +((crdate + '00:00:00'::interval) <= '2005-01-28 00:00:00'::timestamp +without time zone))" +" -> Hash (cost=1449.70..1449.70 rows=684 +width=134) (actual time=267.568..267.568 rows=13587 loops=1)" +" -> Nested Loop (cost=20.59..1449.70 +rows=684 width=134) (actual time=33.099..178.524 rows=13587 loops=1)" +" -> Seq Scan on gl (cost=0.00..5.21 +rows=2 width=91) (actual time=0.021..0.357 rows=1 loops=1)" +" Filter: (glsoctrl = 1)" +" -> Bitmap Heap Scan on cs +(cost=20.59..684.42 rows=3026 width=43) (actual time=33.047..115.151 +rows=13587 loops=1)" +" Recheck Cond: ((cs.csglnum)::text += ("outer".glnum)::text)" +" Filter: ('M'::text = +(csypnum)::text)" +" -> Bitmap Index Scan on +cs_gl_fk (cost=0.00..20.59 rows=3026 width=0) (actual +time=32.475..32.475 rows=13587 loops=1)" +" Index Cond: +((cs.csglnum)::text = ("outer".glnum)::text)" +" -> Sort (cost=156.22..159.65 rows=1372 width=509) (actual +time=239.315..254.024 rows=8974 loops=1)" +" Sort Key: (rr.rrnum)::text" +" -> Seq Scan on rr (cost=0.00..84.72 rows=1372 +width=509) (actual time=0.055..33.564 rows=1372 loops=1)" +" -> Sort (cost=142.29..144.55 rows=903 width=72) (actual +time=60.246..74.813 rows=8932 loops=1)" +" Sort Key: (yr.yrref)::text" +" -> Bitmap Heap Scan on yr (cost=16.42..97.96 rows=903 +width=72) (actual time=8.513..13.587 rows=1154 loops=1)" +" Recheck Cond: (((yryotype)::text = 'Client'::text) AND +((yryonum)::text = 'Comptabilite.Recevable.Regroupement'::text))" +" -> Bitmap Index Scan on yr_idx1 (cost=0.00..16.42 +rows=903 width=0) (actual time=8.471..8.471 rows=1154 loops=1)" +" Index Cond: (((yryotype)::text = 'Client'::text) +AND ((yryonum)::text = 'Comptabilite.Recevable.Regroupement'::text))" +"Total runtime: 2466.197 ms" + +>Bricklen Anderson <BAnderson@PresiNET.com> writes: +> +> +>>Your loops are what is causing the time spent. +>>eg. "actual time=0.127..17.379 rows=1154 loops=8335)" == +>>8335*(17.379-0.127)/1000=>143 secs (if my math is correct). +>> +>> +> +>As for where the problem is, I think it's the horrid misestimate of the +>number of matching rows in cs_pk: +> +> +> +>>>" -> Index Scan using cs_pk on cs (cost=0.00..12.83 +>>>rows=2 width=144) (actual time=0.087..444.999 rows=13587 loops=1)" +>>>" Index Cond: (('M'::text = (cs.csypnum)::text) +>>>AND ((cs.csglnum)::text = ("outer".glnum)::text))" +>>> +>>> +> +>Has that table been ANALYZEd recently? How about the gl table? +> +> regards, tom lane +> +> +> + + +From pgsql-performance-owner@postgresql.org Mon Nov 28 23:19:46 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id A62939DCBE6 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 23:19:44 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 01264-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 23:19:47 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from cobalt.clickspace.com (mail.clickspace.com [65.110.166.234]) + by postgresql.org (Postfix) with ESMTP id 6CE109DCB6F + for <pgsql-performance@postgresql.org>; + Mon, 28 Nov 2005 23:19:41 -0400 (AST) +Received: from [192.168.5.172] ([68.145.108.192]) + by cobalt.clickspace.com (8.10.2/8.10.2) with ESMTP id jAT3JRK03281; + Mon, 28 Nov 2005 20:19:27 -0700 +In-Reply-To: <Pine.LNX.4.62.0511271903180.2807@qnivq.ynat.uz> +References: <BFB0BF1B.1495C%llonergan@greenplum.com> + <179B5137-F0BB-4037-A5AD-3459B914E580@clickspace.com> + <Pine.LNX.4.62.0511271903180.2807@qnivq.ynat.uz> +Mime-Version: 1.0 (Apple Message framework v746.2) +Content-Type: multipart/signed; micalg=sha1; boundary=Apple-Mail-2-308359218; + protocol="application/pkcs7-signature" +Message-Id: <3017A204-1BAF-4E62-ADA6-695E34557645@clickspace.com> +Cc: pgsql-performance@postgresql.org +From: Brendan Duddridge <brendan@clickspace.com> +Subject: Re: Hardware/OS recommendations for large databases ( +Date: Mon, 28 Nov 2005 20:19:41 -0700 +To: David Lang <dlang@invendra.net> +X-Mailer: Apple Mail (2.746.2) +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/546 +X-Sequence-Number: 15803 + + +--Apple-Mail-2-308359218 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; + charset=US-ASCII; + delsp=yes; + format=flowed + +Hi David, + +Thanks for your reply. So how is that different than something like +Slony2 or pgcluster with multi-master replication? Is it similar +technology? We're currently looking for a good clustering solution +that will work on our Apple Xserves and Xserve RAIDs. + +Thanks, + +____________________________________________________________________ +Brendan Duddridge | CTO | 403-277-5591 x24 | brendan@clickspace.com + +ClickSpace Interactive Inc. +Suite L100, 239 - 10th Ave. SE +Calgary, AB T2G 0V9 + +http://www.clickspace.com + +On Nov 27, 2005, at 8:09 PM, David Lang wrote: + +> On Mon, 28 Nov 2005, Brendan Duddridge wrote: +> +>> Forgive my ignorance, but what is MPP? Is that part of Bizgres? Is +>> it possible to upgrade from Postgres 8.1 to Bizgres? +> +> MPP is the Greenplum propriatary extention to postgres that spreads +> the data over multiple machines, (raid, but with entire machines +> not just drives, complete with data replication within the cluster +> to survive a machine failing) +> +> for some types of queries they can definantly scale lineraly with +> the number of machines (other queries are far more difficult and +> the overhead of coordinating the machines shows more. this is one +> of the key things that the new version they recently announced the +> beta for is supposed to be drasticly improving) +> +> early in the year when I first looked at them their prices were +> exorbadent, but Luke says I'm wildly mistake on their current +> prices so call them for details +> +> it uses the same interfaces as postgres so it should be a drop in +> replacement to replace a single server with a cluster. +> +> it's facinating technology to read about. +> +> I seem to remember reading that one of the other postgres companies +> is also producing a clustered version of postgres, but I don't +> remember who and know nothing about them. +> +> David Lang +> + + +--Apple-Mail-2-308359218 +Content-Transfer-Encoding: base64 +Content-Type: application/pkcs7-signature; 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+ Mon, 28 Nov 2005 23:30:54 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 01674-06 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Mon, 28 Nov 2005 23:30:57 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from toad.mtbrook.bozemanpass.com (toad.mtbrook.bozemanpass.com + [69.145.82.195]) + by postgresql.org (Postfix) with ESMTP id E1C5B9DCC19 + for <pgsql-performance@postgresql.org>; + Mon, 28 Nov 2005 23:30:50 -0400 (AST) +Received: from [69.145.82.253] (unknown [69.145.82.253]) + by toad.mtbrook.bozemanpass.com (Postfix) with ESMTP id 2E69B1102E6 + for <pgsql-performance@postgresql.org>; + Mon, 28 Nov 2005 19:30:52 -0800 (PST) +Message-ID: <438BCB6D.3090406@boreham.org> +Date: Mon, 28 Nov 2005 20:30:53 -0700 +From: David Boreham <david_list@boreham.org> +User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: Hardware/OS recommendations for large databases ( +References: <BFB0BF1B.1495C%llonergan@greenplum.com> + <179B5137-F0BB-4037-A5AD-3459B914E580@clickspace.com> + <Pine.LNX.4.62.0511271903180.2807@qnivq.ynat.uz> + <3017A204-1BAF-4E62-ADA6-695E34557645@clickspace.com> +In-Reply-To: <3017A204-1BAF-4E62-ADA6-695E34557645@clickspace.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/547 +X-Sequence-Number: 15804 + +Brendan Duddridge wrote: + +> Thanks for your reply. So how is that different than something like +> Slony2 or pgcluster with multi-master replication? Is it similar +> technology? We're currently looking for a good clustering solution +> that will work on our Apple Xserves and Xserve RAIDs. + +I think you need to be more specific about what you're trying to do. +'clustering' encompasses so many things that it means almost nothing by +itself. + +slony provides facilities for replicating data. Its primary purpose is +to improve reliability. MPP distributes both data and queries. Its +primary purpose is to improve performance for a subset of all query types. + + + +From pgsql-performance-owner@postgresql.org Tue Nov 29 03:34:07 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 95DC89DD600 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 29 Nov 2005 03:33:43 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 00746-01-4 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 29 Nov 2005 03:33:40 -0400 (AST) +X-Greylist: delayed 00:31:09.386303 by SQLgrey- +Received: from mx2.buaa.edu.cn (mx2.buaa.edu.cn [219.239.227.26]) + by postgresql.org (Postfix) with ESMTP id 2471C9DD557 + for <pgsql-performance@postgresql.org>; + Tue, 29 Nov 2005 03:31:38 -0400 (AST) +Received: from mx1.buaa.edu.cn (mx1.buaa.edu.cn [192.168.128.5]) + by mx2.buaa.edu.cn (Postfix) with ESMTP id 8294B37F78 + for <pgsql-performance@postgresql.org>; + Tue, 29 Nov 2005 14:59:44 +0800 (CST) +Received: from [203.86.95.74] by 10.0.0.130 with StormMail ESMTP id + 99741.1939646864; Tue, 29 Nov 2005 15:52:07 +0800 (CST) +Date: Tue, 29 Nov 2005 15:00:22 +0800 +From: "energumen@buaa.edu.cn" <energumen@buaa.edu.cn> +To: "pgsql-performance" <pgsql-performance@postgresql.org> +Subject: index auto changes after copying data ? +X-mailer: Foxmail 5.0 [cn] +Mime-Version: 1.0 +Content-Type: text/plain; + charset="gb2312" +Content-Transfer-Encoding: 7bit +Message-Id: <20051129065944.8294B37F78@mx2.buaa.edu.cn> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=4.813 required=5 tests=[DNS_FROM_RFC_ABUSE=0.479, + DNS_FROM_RFC_WHOIS=0.879, RCVD_DOUBLE_IP_SPAM=3.455] +X-Spam-Score: 4.813 +X-Spam-Level: **** +X-Archive-Number: 200511/550 +X-Sequence-Number: 15807 + +I know in mysql, index will auto change after copying data +Of course, index will change after inserting a line in postgresql, but what about copying data? + + +From pgsql-performance-owner@postgresql.org Tue Nov 29 08:17:09 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id B695B9DCC80 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 29 Nov 2005 08:17:06 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 21583-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 29 Nov 2005 08:17:07 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.metronet.co.uk (mail.metronet.co.uk [213.162.97.75]) + by postgresql.org (Postfix) with ESMTP id 241C09DCBF7 + for <pgsql-performance@postgresql.org>; + Tue, 29 Nov 2005 08:17:03 -0400 (AST) +Received: from mainbox.archonet.com + (84-51-143-99.archon037.adsl.metronet.co.uk [84.51.143.99]) + by smtp.metronet.co.uk (MetroNet Mail) with ESMTP + id AC6D5408E5E; Tue, 29 Nov 2005 12:16:13 +0000 (GMT) +Received: from [192.168.1.17] (client17.office.archonet.com [192.168.1.17]) + by mainbox.archonet.com (Postfix) with ESMTP id 0B2C315EA4; + Tue, 29 Nov 2005 12:16:21 +0000 (GMT) +Message-ID: <438C4694.3010502@archonet.com> +Date: Tue, 29 Nov 2005 12:16:20 +0000 +From: Richard Huxton <dev@archonet.com> +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: "energumen@buaa.edu.cn" <energumen@buaa.edu.cn> +Cc: pgsql-performance <pgsql-performance@postgresql.org> +Subject: Re: index auto changes after copying data ? +References: <20051129065944.8294B37F78@mx2.buaa.edu.cn> +In-Reply-To: <20051129065944.8294B37F78@mx2.buaa.edu.cn> +Content-Type: text/plain; charset=GB2312 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/551 +X-Sequence-Number: 15808 + +energumen@buaa.edu.cn wrote: +> I know in mysql, index will auto change after copying data +> Of course, index will change after inserting a line in postgresql, but what about copying data? + +The index will (of course) know about the new data. +You might want to ANALYZE the table again after a large copy in case the +statistics about how many different values are present changes. + +-- + Richard Huxton + Archonet Ltd + +From pgsql-performance-owner@postgresql.org Tue Nov 29 15:04:12 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 95CBD9DCBB7 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 29 Nov 2005 15:04:10 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 17436-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Tue, 29 Nov 2005 15:04:09 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) + by postgresql.org (Postfix) with ESMTP id F266E9DCADF + for <pgsql-performance@postgresql.org>; + Tue, 29 Nov 2005 15:04:06 -0400 (AST) +Received: by floppy.pyrenet.fr (Postfix, from userid 106) + id 752643358C; Tue, 29 Nov 2005 20:04:07 +0100 (MET) +From: Chris Browne <cbbrowne@acm.org> +X-Newsgroups: pgsql.performance +Subject: Re: index auto changes after copying data ? +Date: Tue, 29 Nov 2005 13:48:49 -0500 +Organization: cbbrowne Computing Inc +Lines: 19 +Message-ID: <60zmnn1e9a.fsf@dba2.int.libertyrms.com> +References: <20051129065944.8294B37F78@mx2.buaa.edu.cn> +Mime-Version: 1.0 +Content-Type: text/plain; charset=iso-8859-1 +X-Complaints-To: usenet@news.hub.org +User-Agent: Gnus/5.1007 (Gnus v5.10.7) XEmacs/21.4.17 (Jumbo Shrimp, linux) +Cancel-Lock: sha1:p2ywLvgGkAWWRVpnxWqLIcB/rpA= +To: pgsql-performance@postgresql.org +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.142 required=5 tests=[AWL=0.142] +X-Spam-Score: 0.142 +X-Spam-Level: +X-Archive-Number: 200511/552 +X-Sequence-Number: 15809 + +energumen@buaa.edu.cn ("energumen@buaa.edu.cn") writes: +> I know in mysql, index will auto change after copying data Of +> course, index will change after inserting a line in postgresql, but +> what about copying data? + +Do you mean, by this, something like... + +"Are indexes affected by loading data using the COPY command just as +they are if data is loaded using INSERT?" + +If so, then the answer is "Yes, certainly." Indexes are updated +whichever statement you use to load in data. +-- +let name="cbbrowne" and tld="acm.org" in name ^ "@" ^ tld;; +http://www.ntlug.org/~cbbrowne/finances.html +Rules of the Evil Overlord #160. "Before being accepted into my +Legions of Terror, potential recruits will have to pass peripheral +vision and hearing tests, and be able to recognize the sound of a +pebble thrown to distract them." <http://www.eviloverlord.com/> + +From pgsql-performance-owner@postgresql.org Wed Nov 30 08:37:44 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 451089DCAD3 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 08:37:43 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14458-02 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 08:37:44 -0400 (AST) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.206]) + by postgresql.org (Postfix) with ESMTP id 5F9229DCBC4 + for <pgsql-performance@postgresql.org>; + Wed, 30 Nov 2005 08:37:40 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id 69so83628wri + for <pgsql-performance@postgresql.org>; + Wed, 30 Nov 2005 04:37:42 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:from:to:subject:date:message-id:mime-version:content-type:content-transfer-encoding:x-priority:x-msmail-priority:x-mailer:importance:x-mimeole; + b=L19YFDnsYN71RwBVaSTv/OFEHHI3eMuGAftk1yLKNnVvuWP2PWUmJTwNgIhm0gGPk4v6vnhQfcAkb/fddhG8mgiEWhyV0zOU7VZQq9MASWqFGDhrm6SOS5ZSNzI+pQLZP4zRxcEaTk38Q4CwJIAYwe2jBbtk/4t8AiTrgYbWXQ0= +Received: by 10.54.62.18 with SMTP id k18mr463212wra; + Wed, 30 Nov 2005 04:37:41 -0800 (PST) +Received: from FRANKLIN ( [200.180.51.99]) + by mx.gmail.com with ESMTP id 34sm254011wra.2005.11.30.04.37.40; + Wed, 30 Nov 2005 04:37:41 -0800 (PST) +From: "Franklin Haut" <franklin.haut@gmail.com> +To: <pgsql-performance@postgresql.org> +Subject: pg_dump slow +Date: Wed, 30 Nov 2005 10:35:05 -0300 +Message-ID: <000201c5f5b2$e0dc87a0$8500a8c0@FRANKLIN> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: quoted-printable +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook, Build 10.0.4024 +Importance: Normal +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/553 +X-Sequence-Number: 15810 + +Hi=20 + +i=B4m using PostgreSQL on windows 2000, the pg_dump take around 50 = +minutes +to do backup of 200Mb data ( with no compression, and 15Mb with +compression), but in windows XP does not pass of 40 seconds... :( + +This happens with 8.1 and version 8.0, somebody passed for the same +situation?=20 + +It will be that a configuration in the priorities of the exists +processes ? in Windows XP the processing of schemes goes 70% and +constant accesses to the HardDisk, while that in windows 2000 it does +not pass of 3%. + +thanks + +Franklin + + +From pgsql-performance-owner@postgresql.org Wed Nov 30 09:56:49 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 9BDB89DCC70 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 09:56:48 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 18799-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 09:56:50 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtpauth01.mail.atl.earthlink.net + (smtpauth01.mail.atl.earthlink.net [209.86.89.61]) + by postgresql.org (Postfix) with ESMTP id AD1BD9DCC3E + for <pgsql-performance@postgresql.org>; + Wed, 30 Nov 2005 09:56:45 -0400 (AST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; + d=earthlink.net; + b=CnMSTS2LnkEbMpI5cN+7igqKMCJXQGpzPzV7uWy5OLsDYfl1m09mjl/7PoS9J6u8; + h=Received:Message-Id:X-Mailer:Date:To:From:Subject:In-Reply-To:References:Mime-Version:Content-Type:Content-Transfer-Encoding:X-ELNK-Trace:X-Originating-IP; +Received: from [70.22.193.119] (helo=ron-6d52adff2a6.earthlink.net) + by smtpauth01.mail.atl.earthlink.net with asmtp (Exim 4.34) + id 1EhSRx-0000Nh-78; Wed, 30 Nov 2005 08:56:45 -0500 +Message-Id: <6.2.5.6.0.20051130081636.01da1d48@earthlink.net> +X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6 +Date: Wed, 30 Nov 2005 08:56:41 -0500 +To: "Franklin Haut" <franklin.haut@gmail.com>, + <pgsql-performance@postgresql.org> +From: Ron <rjpeace@earthlink.net> +Subject: Re: pg_dump slow +In-Reply-To: <000201c5f5b2$e0dc87a0$8500a8c0@FRANKLIN> +References: <000201c5f5b2$e0dc87a0$8500a8c0@FRANKLIN> +Mime-Version: 1.0 +Content-Type: text/plain; charset="iso-8859-1"; format=flowed +Content-Transfer-Encoding: quoted-printable +X-ELNK-Trace: + acd68a6551193be5d780f4a490ca69563f9fea00a6dd62bc48be752cdf4fcce139ec5dd9f6f6a343350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c +X-Originating-IP: 70.22.193.119 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.359 required=5 tests=[AWL=-0.120, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.359 +X-Spam-Level: +X-Archive-Number: 200511/554 +X-Sequence-Number: 15811 + +At 08:35 AM 11/30/2005, Franklin Haut wrote: +>Hi +> +>i=B4m using PostgreSQL on windows 2000, the pg_dump take around 50 minutes +>to do backup of 200Mb data ( with no compression, and 15Mb with +>compression), + +Compression is reducing the data to 15/200=3D 3/40=3D 7.5% of original size? + +>but in windows XP does not pass of 40 seconds... :( + +You mean that 40 secs in pg_dump under Win XP=20 +crashes, and therefore you have a WinXP problem? + +Or do you mean that pg_dump takes 40 secs to=20 +complete under WinXP and 50 minutes under W2K and=20 +therefore you have a W2K problem? + +In fact, either 15MB/40secs=3D 375KBps or=20 +200MB/40secs=3D 5MBps is _slow_, so there's a problem under either platform! + +>This happens with 8.1 and version 8.0, somebody=20 +>passed for the same situation? +> +>It will be that a configuration in the priorities of the exists +>processes ? in Windows XP the processing of schemes goes 70% and +>constant accesses to the HardDisk, while that in windows 2000 it does +>not pass of 3%. +Assuming Win XP completes the dump, the first thing to do is +*don't use W2K* +M$ has stopped supporting it in anything but absolutely minimum fashion= + anyway. + _If_ you are going to use an M$ OS you should be using WinXP. +(You want to pay licensing fees for your OS, but=20 +you are using free DB SW? Huh? If you are=20 +trying to save $$$, use Open Source SW like Linux=20 +or *BSD. pg will perform better under it, and it's cheaper!) + + +Assuming that for some reason you can't/won't=20 +migrate to a non-M$ OS, the next problem is the=20 +slow HD IO you are getting under WinXP. + +What is the HW involved here? Particularly the=20 +HD subsystem and the IO bus(es) it is plugged into? + +For some perspective, Raw HD average IO rates for=20 +even reasonably modern 7200rpm HD's is in the=20 +~50MBps per HD range. Top of the line 15Krpm=20 +SCSI and FC HD's have raw average IO rates of=20 +just under 80MBps per HD as of this post. + +Given that most DB's are not on 1 HD (if you DB=20 +_is_ on only 1 HD, change that ASAP before you=20 +lose data...), for anything other than a 2 HD=20 +RAID 1 set I'd expect raw HD average IO rates to be at least 100MBps. + +If you are getting >=3D 100MBps of average HD IO,=20 +you should be getting > 5MBps during pg_dump, and certainly > 375MBps! + +Ron + + + +From pgsql-performance-owner@postgresql.org Wed Nov 30 11:23:32 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 9364C9DCCDD + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 11:23:31 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 24351-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 11:23:34 -0400 (AST) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.192]) + by postgresql.org (Postfix) with ESMTP id 0ECAD9DCCBE + for <pgsql-performance@postgresql.org>; + Wed, 30 Nov 2005 11:23:26 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id 71so4277wra + for <pgsql-performance@postgresql.org>; + Wed, 30 Nov 2005 07:23:32 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:from:to:subject:date:message-id:mime-version:content-type:content-transfer-encoding:x-priority:x-msmail-priority:x-mailer:in-reply-to:x-mimeole:importance; + b=WtvlmfG2BPDq6PUczw2aH5f38ucS8KwZgF5+sSPUGfLUY30CZhY/wuKlUqPrpz6+uVIC9Z7i+gScihDIDjRqUVH9AksWoSqKFAf/rWvyFK/rqm9qkXUHt+sFP+Q/XgXkPW52CBPBPoNxXdqAqRPqPsVQV+k9s4O9cMFsLG5h7Ds= +Received: by 10.54.76.17 with SMTP id y17mr356431wra; + Wed, 30 Nov 2005 07:23:31 -0800 (PST) +Received: from FRANKLIN ( [200.180.51.99]) + by mx.gmail.com with ESMTP id 39sm67476wrl.2005.11.30.07.23.28; + Wed, 30 Nov 2005 07:23:31 -0800 (PST) +From: "Franklin Haut" <franklin.haut@gmail.com> +To: "'Ron'" <rjpeace@earthlink.net>, + <pgsql-performance@postgresql.org> +Subject: RES: pg_dump slow +Date: Wed, 30 Nov 2005 13:20:51 -0300 +Message-ID: <000401c5f5ca$0aed7420$8500a8c0@FRANKLIN> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: quoted-printable +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook, Build 10.0.4024 +In-Reply-To: <6.2.5.6.0.20051130081636.01da1d48@earthlink.net> +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 +Importance: Normal +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/555 +X-Sequence-Number: 15812 + +Hi, + +Yes, my problem is that the pg_dump takes 40 secs to complete under +WinXP and 50 minutes under W2K! The same database, the same hardware!, +only diferrent Operational Systems. + +The hardware is:=20 + Pentium4 HT 3.2 GHz + 1024 Mb Memory + HD 120Gb SATA + +Im has make again the test, and then real size of database is 174Mb +(avaliable on pg_admin, properties) and the file size of pg_dump is 18Mb +( with command line pg_dump -i -F c -b -v -f "C:\temp\BackupTest.bkp" +NameOfDatabase ). The time was equal in 40 seconds on XP and 50 minutes +on W2K, using PG 8.1 + +Unhappyly for some reasons I cannot use other platforms, I need use PG +on Windows, and must be W2K. + +Is strange to have a so great difference in the time of execution of +dump, therefore the data are the same ones and the archive is being +correctly generated in both OS. + +Franklin + +-----Mensagem original----- +De: Ron [mailto:rjpeace@earthlink.net]=20 +Enviada em: quarta-feira, 30 de novembro de 2005 10:57 +Para: Franklin Haut; pgsql-performance@postgresql.org +Assunto: Re: [PERFORM] pg_dump slow + + +At 08:35 AM 11/30/2005, Franklin Haut wrote: +>Hi +> +>i=B4m using PostgreSQL on windows 2000, the pg_dump take around 50=20 +>minutes to do backup of 200Mb data ( with no compression, and 15Mb with + +>compression), + +Compression is reducing the data to 15/200=3D 3/40=3D 7.5% of original = +size? + +>but in windows XP does not pass of 40 seconds... :( + +You mean that 40 secs in pg_dump under Win XP=20 +crashes, and therefore you have a WinXP problem? + +Or do you mean that pg_dump takes 40 secs to=20 +complete under WinXP and 50 minutes under W2K and=20 +therefore you have a W2K problem? + +In fact, either 15MB/40secs=3D 375KBps or=20 +200MB/40secs=3D 5MBps is _slow_, so there's a problem under either +platform! + +>This happens with 8.1 and version 8.0, somebody +>passed for the same situation? +> +>It will be that a configuration in the priorities of the exists=20 +>processes ? in Windows XP the processing of schemes goes 70% and=20 +>constant accesses to the HardDisk, while that in windows 2000 it does=20 +>not pass of 3%. +Assuming Win XP completes the dump, the first thing to do is *don't use +W2K* M$ has stopped supporting it in anything but absolutely minimum +fashion anyway. + _If_ you are going to use an M$ OS you should be using WinXP. (You +want to pay licensing fees for your OS, but=20 +you are using free DB SW? Huh? If you are=20 +trying to save $$$, use Open Source SW like Linux=20 +or *BSD. pg will perform better under it, and it's cheaper!) + + +Assuming that for some reason you can't/won't=20 +migrate to a non-M$ OS, the next problem is the=20 +slow HD IO you are getting under WinXP. + +What is the HW involved here? Particularly the=20 +HD subsystem and the IO bus(es) it is plugged into? + +For some perspective, Raw HD average IO rates for=20 +even reasonably modern 7200rpm HD's is in the=20 +~50MBps per HD range. Top of the line 15Krpm=20 +SCSI and FC HD's have raw average IO rates of=20 +just under 80MBps per HD as of this post. + +Given that most DB's are not on 1 HD (if you DB=20 +_is_ on only 1 HD, change that ASAP before you=20 +lose data...), for anything other than a 2 HD=20 +RAID 1 set I'd expect raw HD average IO rates to be at least 100MBps. + +If you are getting >=3D 100MBps of average HD IO,=20 +you should be getting > 5MBps during pg_dump, and certainly > 375MBps! + +Ron + + + +From pgsql-performance-owner@postgresql.org Wed Nov 30 13:22:26 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 0DD4B9DD675 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 13:21:51 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 00620-04-2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 13:21:46 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by postgresql.org (Postfix) with ESMTP id 4E1689DD551 + for <pgsql-performance@postgresql.org>; + Wed, 30 Nov 2005 12:56:56 -0400 (AST) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: quoted-printable +X-MimeOLE: Produced By Microsoft Exchange V6.5 +Subject: Re: pg_dump slow +Date: Wed, 30 Nov 2005 11:56:50 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD9BE@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] pg_dump slow +Thread-Index: AcX1tfwWOKcWjlb8Th6i5ZAuqxXZdQACwGbg +From: "Merlin Moncure" <merlin.moncure@rcsonline.com> +To: "Ron" <rjpeace@earthlink.net> +Cc: <pgsql-performance@postgresql.org>, + "Franklin Haut" <franklin.haut@gmail.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/556 +X-Sequence-Number: 15813 + +> At 08:35 AM 11/30/2005, Franklin Haut wrote: +> >Hi +> > +> >i=B4m using PostgreSQL on windows 2000, the pg_dump take around 50 = +minutes +> >to do backup of 200Mb data ( with no compression, and 15Mb with +> >compression), +>=20 +> Compression is reducing the data to 15/200=3D 3/40=3D 7.5% of original = +size? +>=20 +> >but in windows XP does not pass of 40 seconds... :( +>=20 +> You mean that 40 secs in pg_dump under Win XP +> crashes, and therefore you have a WinXP problem? +>=20 +> Or do you mean that pg_dump takes 40 secs to +> complete under WinXP and 50 minutes under W2K and +> therefore you have a W2K problem? + +I think he is saying the time to dump does not take more than 40 = +seconds, but I'm not sure. +=20 +> In fact, either 15MB/40secs=3D 375KBps or +> 200MB/40secs=3D 5MBps is _slow_, so there's a problem under either = +platform! + +5 mb/sec dump output from psql is not terrible or even bad, depending on = +hardware. + +> >not pass of 3%. +> Assuming Win XP completes the dump, the first thing to do is +> *don't use W2K* + +XP is not a server platform. Next level up is 2003 server. Many = +organizations still have 2k deployed. About half of my servers still = +run it. Anyways, the 2k/xp issue does not explain why there is a = +performance problem. + +> M$ has stopped supporting it in anything but absolutely minimum = +fashion +> anyway. +> _If_ you are going to use an M$ OS you should be using WinXP. +> (You want to pay licensing fees for your OS, but +> you are using free DB SW? Huh? If you are +> trying to save $$$, use Open Source SW like Linux +> or *BSD. pg will perform better under it, and it's cheaper!) + +I would like to see some benchmarks supporting those claims. No comment = +on licensing issue, but there are many other factors in considering = +server platform than licensing costs. That said, there were several = +win32 specific pg performance issues that were rolled up into the 8.1 = +release. So for win32 you definitely want to be running 8.1. +=20 +> Assuming that for some reason you can't/won't +> migrate to a non-M$ OS, the next problem is the +> slow HD IO you are getting under WinXP. + +Problem is almost certainly not related to disk unless there is a = +imminent disk failure. Could be TCP/IP issue (are you running pg_dump = +from remote box?), or possibly a network driver issue or some other = +weird software issue. Can you determine if disk is running normally = +with respect to other applications? Is this a fresh win2k install? A = +LSP, virus scanner, backup software, or some other garbage can really = +ruin your day. + +Merlin + + +From pgsql-performance-owner@postgresql.org Wed Nov 30 13:38:19 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 47E189DCAB1 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 13:38:16 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 01957-05 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 13:38:14 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from mail.metronet.co.uk (mail.metronet.co.uk [213.162.97.75]) + by postgresql.org (Postfix) with ESMTP id 7A3C69DCAD3 + for <pgsql-performance@postgresql.org>; + Wed, 30 Nov 2005 13:38:12 -0400 (AST) +Received: from mainbox.archonet.com + (84-51-143-99.archon037.adsl.metronet.co.uk [84.51.143.99]) + by smtp.metronet.co.uk (MetroNet Mail) with ESMTP + id BE84C43B8CB; Wed, 30 Nov 2005 17:27:23 +0000 (GMT) +Received: from [192.168.1.17] (client17.office.archonet.com [192.168.1.17]) + by mainbox.archonet.com (Postfix) with ESMTP id 068F7FF1A; + Wed, 30 Nov 2005 17:27:35 +0000 (GMT) +Message-ID: <438DE107.9000507@archonet.com> +Date: Wed, 30 Nov 2005 17:27:35 +0000 +From: Richard Huxton <dev@archonet.com> +User-Agent: Thunderbird 1.5 (X11/20051025) +MIME-Version: 1.0 +To: Franklin Haut <franklin.haut@gmail.com> +Cc: 'Ron' <rjpeace@earthlink.net>, pgsql-performance@postgresql.org +Subject: Re: RES: pg_dump slow +References: <000401c5f5ca$0aed7420$8500a8c0@FRANKLIN> +In-Reply-To: <000401c5f5ca$0aed7420$8500a8c0@FRANKLIN> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[AWL=0.000] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/557 +X-Sequence-Number: 15814 + +Franklin Haut wrote: +> Hi, +> +> Yes, my problem is that the pg_dump takes 40 secs to complete under +> WinXP and 50 minutes under W2K! The same database, the same hardware!, +> only diferrent Operational Systems. +> +> The hardware is: +> Pentium4 HT 3.2 GHz +> 1024 Mb Memory +> HD 120Gb SATA + +There have been reports of very slow network performance on Win2k +systems with the default configuration. You'll have to check the +archives for details I'm afraid. This might apply to you. + +If you're happy that doesn't affect you then I'd look at the disk system +- perhaps XP has newer drivers than Win2k. + +What do the MS performance-charts show is happening? Specifically, CPU +and disk I/O. + +-- + Richard Huxton + Archonet Ltd + +From pgsql-performance-owner@postgresql.org Wed Nov 30 15:22:04 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 9D1379DCD40 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 15:21:13 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 09390-03 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 15:21:12 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from svr2.postgresql.org (svr2.postgresql.org [65.19.161.25]) + by postgresql.org (Postfix) with ESMTP id 2E0E79DCD3C + for <pgsql-performance@postgresql.org>; + Wed, 30 Nov 2005 15:21:10 -0400 (AST) +Received: from dc1.storediq.com (66-194-80-196.gen.twtelecom.net + [66.194.80.196]) + by svr2.postgresql.org (Postfix) with ESMTP id 0611AF0B01 + for <pgsql-performance@postgresql.org>; + Wed, 30 Nov 2005 19:19:50 +0000 (GMT) +content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Select with grouping plan question +X-MIMEOLE: Produced By Microsoft Exchange V6.0.6603.0 +Date: Wed, 30 Nov 2005 13:21:07 -0600 +Message-ID: <E387E2E9622FDD408359F98BF183879E222A6A@dc1.storediq.com> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: Select with grouping plan question +Thread-Index: AcX10FdK1onJ28n0QO2nK/b0p2adYQAEs69g +From: "Brad Might" <bmight@storediq.com> +To: <pgsql-performance@postgresql.org> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/558 +X-Sequence-Number: 15815 + +=20 + +This seems to me to be an expensive plan and I'm wondering if there's a +way to improve it or a better way to do what I'm trying to do here (get +a count of distinct values for each record_id and map that value to the +entity type) entity_type_id_mapping is 56 rows +volume_node_entity_data_values is approx 500,000,000 rows vq_record_id +has approx 11,000,000 different values vq_entity_type is a value in +entity_type_id_mapping.entity_type + +I thought that the idx_vq_entities_1 index would allow an ordered scan +of the table. I created it based pon the sort key given in the explain +statement.=20 + +Thanks in advance. + + Table "data_schema.volume_queue_entities" + Column | Type | Modifiers + +-----------------+-------------------+---------------------------------- +-----------------+-------------------+------------- + vq_record_id | bigint | default +currval('seq_vq_fsmd_auto'::regclass) + vq_entity_type | character varying | + vq_entity_value | character varying | +Indexes: + "idx_vq_entities_1" btree (vq_record_id, vq_entity_type, +vq_entity_value) + + + + Table "volume_8.entity_type_id_mapping" + Column | Type | Modifiers + +-------------+-------------------+-------------------------------------- +-------------+-------------------+-------------------- + entity_id | integer | default +nextval('volume_8.entity_id_sequence'::regclass) + entity_type | character varying |=20 + + + +explain insert into volume_8.volume_node_entity_data_values +(vs_volume_id, vs_latest_node_synthetic_id, vs_base_entity_id, vs_value, +vs_value_count, vs_base_entity_revision_id) + select 8, vq_record_id, entity_id , vq_entity_value, +count(vq_entity_value),1 from data_schema.volume_queue_entities qe, +volume_8.entity_type_id_mapping emap + where qe.vq_entity_type =3D emap.entity_type group by +vq_record_id, vq_entity_type, vq_entity_value, entity_id ; + + +------------------------------------------------------------------------ +---------------------------------------- + Subquery Scan "*SELECT*" (cost=3D184879640.90..210689876.26 +rows=3D543373376 width=3D60) + -> GroupAggregate (cost=3D184879640.90..199822408.74 = +rows=3D543373376 +width=3D37) + -> Sort (cost=3D184879640.90..186238074.34 rows=3D543373376 +width=3D37) + Sort Key: qe.vq_record_id, qe.vq_entity_type, +qe.vq_entity_value, emap.entity_id + -> Hash Join (cost=3D1.70..18234833.10 rows=3D543373376 +width=3D37) + Hash Cond: (("outer".vq_entity_type)::text =3D +("inner".entity_type)::text) + -> Seq Scan on volume_queue_entities qe +(cost=3D0.00..10084230.76 rows=3D543373376 width=3D33) + -> Hash (cost=3D1.56..1.56 rows=3D56 width=3D16) + -> Seq Scan on entity_type_id_mapping emap +(cost=3D0.00..1.56 rows=3D56 width=3D16) +(9 rows) + + +From pgsql-performance-owner@postgresql.org Wed Nov 30 16:41:28 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 901409DCD2A + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 16:41:26 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 13123-07 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 16:41:25 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) + by postgresql.org (Postfix) with ESMTP id E23839DCD40 + for <pgsql-performance@postgresql.org>; + Wed, 30 Nov 2005 16:41:21 -0400 (AST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id jAUKfMte000816; + Wed, 30 Nov 2005 15:41:22 -0500 (EST) +To: "Brad Might" <bmight@storediq.com> +cc: pgsql-performance@postgresql.org +Subject: Re: Select with grouping plan question +In-reply-to: <E387E2E9622FDD408359F98BF183879E222A6A@dc1.storediq.com> +References: <E387E2E9622FDD408359F98BF183879E222A6A@dc1.storediq.com> +Comments: In-reply-to "Brad Might" <bmight@storediq.com> + message dated "Wed, 30 Nov 2005 13:21:07 -0600" +Date: Wed, 30 Nov 2005 15:41:22 -0500 +Message-ID: <815.1133383282@sss.pgh.pa.us> +From: Tom Lane <tgl@sss.pgh.pa.us> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.004 required=5 tests=[AWL=0.004] +X-Spam-Score: 0.004 +X-Spam-Level: +X-Archive-Number: 200511/560 +X-Sequence-Number: 15817 + +"Brad Might" <bmight@storediq.com> writes: +> This seems to me to be an expensive plan and I'm wondering if there's a +> way to improve it or a better way to do what I'm trying to do here (get +> a count of distinct values for each record_id and map that value to the +> entity type) entity_type_id_mapping is 56 rows +> volume_node_entity_data_values is approx 500,000,000 rows vq_record_id +> has approx 11,000,000 different values vq_entity_type is a value in +> entity_type_id_mapping.entity_type + +Hmm, what Postgres version is that? And have you ANALYZEd +entity_type_id_mapping lately? I'd expect the planner to realize that +there cannot be more than 56 output groups, which ought to lead it to +prefer a hashed aggregate over the sort+group method. That's what I +get in a test case with a similar query structure, anyway. + +If you're stuck on an old PG version, it might help to do the +aggregation first and then join, ie + + select ... from + (select count(vq_entity_value) as vcount, vq_entity_type + from data_schema.volume_queue_entities group by vq_entity_type) qe, + volume_8.entity_type_id_mapping emap + where qe.vq_entity_type = emap.entity_type; + + regards, tom lane + +From pgsql-performance-owner@postgresql.org Wed Nov 30 17:05:54 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 130EB9DCD5A + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 17:05:52 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 14272-08-2 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 17:05:50 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from smtpauth01.mail.atl.earthlink.net + (smtpauth01.mail.atl.earthlink.net [209.86.89.61]) + by postgresql.org (Postfix) with ESMTP id CE7229DCB0E + for <pgsql-performance@postgresql.org>; + Wed, 30 Nov 2005 17:05:46 -0400 (AST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; + d=earthlink.net; + b=X1dDyinABaAaFyjD1XIqd170C3eR7oxgkx8fLn6r2rX2uIOj44W2NMNsx71A3Vt8; + h=Received:Message-Id:X-Mailer:Date:To:From:Subject:Cc:In-Reply-To:References:Mime-Version:Content-Type:X-ELNK-Trace:X-Originating-IP; +Received: from [70.22.193.119] (helo=ron-6d52adff2a6.earthlink.net) + by smtpauth01.mail.atl.earthlink.net with asmtp (Exim 4.34) + id 1EhZ95-0000Z0-E2; Wed, 30 Nov 2005 16:05:43 -0500 +Message-Id: <6.2.5.6.0.20051130152830.01d9e178@earthlink.net> +X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6 +Date: Wed, 30 Nov 2005 16:05:38 -0500 +To: Richard Huxton <dev@archonet.com>, Franklin Haut <franklin.haut@gmail.com> +From: Ron <rjpeace@earthlink.net> +Subject: Re: RES: pg_dump slow +Cc: pgsql-performance@postgresql.org +In-Reply-To: <438DE107.9000507@archonet.com> +References: <000401c5f5ca$0aed7420$8500a8c0@FRANKLIN> + <438DE107.9000507@archonet.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset="us-ascii"; format=flowed +X-ELNK-Trace: + acd68a6551193be5d780f4a490ca69563f9fea00a6dd62bca8a481d806247b11d5ac4574241f7dda350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c +X-Originating-IP: 70.22.193.119 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0.359 required=5 tests=[AWL=-0.120, + DNS_FROM_RFC_ABUSE=0.479] +X-Spam-Score: 0.359 +X-Spam-Level: +X-Archive-Number: 200511/561 +X-Sequence-Number: 15818 + +At 12:27 PM 11/30/2005, Richard Huxton wrote: +>Franklin Haut wrote: +>>Hi, +>>Yes, my problem is that the pg_dump takes 40 secs to complete under +>>WinXP and 50 minutes under W2K! The same database, the same hardware!, +>>only diferrent Operational Systems. +>>The hardware is: Pentium4 HT 3.2 GHz +>> 1024 MB Memory + +Get the RAM up to at least 4096MB= 4GB for a DB server. 4 1GB DIMMs +or 2 2GB DIMMS are ~ the same $$ as a HD (~$250-$300 US) and well +worth the expense. + +>> HD 120GB SATA +"b" is "bit". "B" is "Byte". I made the correction. + +You have =1= HD? and you are using it for everything: OS, pq, swap, etc? +Very Bad Idea. + +At the very least, a DB server should have the OS on separate +spindles from pg, and pg tables should be on something like a 4 HD +RAID 10. At the very least. + +DB servers are about HDs. Lots and lots of HDs compared to anything +outside the DB realm. Start thinking in terms of at least 6+ HD's +attached to the system in question (I've worked on system with +literally 100's). Usually only a few of these are directly attached +to the DB server and most are attached by LAN or FC. But the point +remains: DBs and DB servers eat HDs in prodigious quantities. + + +>There have been reports of very slow network performance on Win2k +>systems with the default configuration. You'll have to check the +>archives for details I'm afraid. This might apply to you. +Unless you are doing IO across a network, this issue will not apply to you. + +By default W2K systems often had a default TCP/IP packet size of 576B +and a tiny RWIN. Optimal for analog modems talking over noisy POTS +lines, but horrible for everything else + +Packet size needs to be boosted to 1500B, the maximum. RWIN should +be boosted to _at least_ the largest number <= 2^16 that you can use +without TCP scaling. Benchmark network IO rates. Then TCP scaling +should be turned on and RWIN doubled and network IO benched +again. Repeat until there is no performance benefit to doubling RWIN +or you run out of RAM that you can afford to toss at the problem or +you hit the max for RWIN (very doubtful). + + + +>If you're happy that doesn't affect you then I'd look at the disk +>system - perhaps XP has newer drivers than Win2k. +I'll reiterate: Do _not_ run a production DB server on W2K. M$ has +obsoleted the platform and that it is not supported _nor_ any of +reliable, secure, etc. etc. + +A W2K based DB server, particularly one with a connection to the +Internet, is a ticking time bomb at this point. +Get off W2K as a production platform ASAP. Take to your +CEO/Dean/whatever you call your Fearless Leader if you have to. + +Economically and probably performance wise, it's best to use an Open +Source OS like Linux or *BSD. However, if you must use M$, at least +use OS's that M$ is actively supporting. + +Despite M$ marketing propaganda and a post in this thread to the +contrary, you =CAN= often run a production DB server under WinXP and +not pay M$ their usurious licensing fees for W2003 Server or any of +their other products with "server" in the title. How much RAM and +how many CPUs you want in your DB server is the main issue. For a +1P, <= 4GB RAM vanilla box, WinXp will work just fine. + + +>What do the MS performance-charts show is happening? Specifically, +>CPU and disk I/O. +His original post said ~3% CPU under W2K and ~70% CPU under WinXP + +Ron + + + +From pgsql-performance-owner@postgresql.org Wed Nov 30 16:39:37 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 6B51E9DCD2A + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 16:39:35 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 13999-04 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 16:39:31 -0400 (AST) +X-Greylist: domain auto-whitelisted by SQLgrey- +Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.197]) + by postgresql.org (Postfix) with ESMTP id 8BECC9DCB0E + for <pgsql-performance@postgresql.org>; + Wed, 30 Nov 2005 16:39:27 -0400 (AST) +Received: by wproxy.gmail.com with SMTP id 71so79247wra + for <pgsql-performance@postgresql.org>; + Wed, 30 Nov 2005 12:39:28 -0800 (PST) +DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; + h=received:from:to:subject:date:message-id:mime-version:content-type:content-transfer-encoding:x-priority:x-msmail-priority:x-mailer:importance:in-reply-to:x-mimeole; + b=hZbVbnU5b9Ukop59iwqW1qF9UHnXR4THE+r48apHLv16nP4vVfcdEtFcbShKnVi2dk64xZxbVZY479VwXtNlHWfQWNdlptMXIFgMpaSv3zQ3lrr9widlkIzC+iUbKO29v/HXEulo6gdeKt8lr+fRxuZfCGjiJXcPqx2byjiBDa8= +Received: by 10.54.110.5 with SMTP id i5mr778588wrc; + Wed, 30 Nov 2005 12:39:20 -0800 (PST) +Received: from FRANKLIN ( [200.180.51.99]) + by mx.gmail.com with ESMTP id 24sm580732wrl.2005.11.30.12.39.18; + Wed, 30 Nov 2005 12:39:19 -0800 (PST) +From: "Franklin Haut" <franklin.haut@gmail.com> +To: "'Merlin Moncure'" <merlin.moncure@rcsonline.com>, + "'Ron'" <rjpeace@earthlink.net>, <pgsql-performance@postgresql.org> +Subject: RES: pg_dump slow +Date: Wed, 30 Nov 2005 18:36:42 -0300 +Message-ID: <000001c5f5f6$29709090$8500a8c0@FRANKLIN> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: quoted-printable +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook, Build 10.0.4024 +Importance: Normal +In-Reply-To: <6EE64EF3AB31D5448D0007DD34EEB3417DD9BE@Herge.rcsinc.local> +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/559 +X-Sequence-Number: 15816 + +Complementing... + + +The test was maked at the same machine ( localhost ) at Command-Prompt, +no client=B4s connected, no concurrent processes only PostgreSQL = +running. + +In windows XP, exists much access to the processor (+- 70%) and HD (I +see HD Led allways on), while in the W2K almost without activity of +processor (3%)and little access to the HardDisk (most time of the led HD +is off). + +Look, the database has 81 Tables, one of these, has 2 fields ( one +integer and another ByteA ), these table as 5.150 Records.=20 +I=B4m Dumpped only this table and the file size is 7Mb (41% of total +(17MB is the total)) was very slow.... Then I Maked Backup of the others +tables was fast! + +So i=B4m conclused that pg_dump and pg_restore is very slow when +manipulates ByteA type on W2K!, is this possible ? + + +Franklin + + + +-----Mensagem original----- +De: Merlin Moncure [mailto:merlin.moncure@rcsonline.com]=20 +Enviada em: quarta-feira, 30 de novembro de 2005 13:57 +Para: Ron +Cc: pgsql-performance@postgresql.org; Franklin Haut +Assunto: RE: [PERFORM] pg_dump slow + + +> At 08:35 AM 11/30/2005, Franklin Haut wrote: +> >Hi +> > +> >i=B4m using PostgreSQL on windows 2000, the pg_dump take around 50=20 +> >minutes to do backup of 200Mb data ( with no compression, and 15Mb=20 +> >with compression), +>=20 +> Compression is reducing the data to 15/200=3D 3/40=3D 7.5% of original = + +> size? +>=20 +> >but in windows XP does not pass of 40 seconds... :( +>=20 +> You mean that 40 secs in pg_dump under Win XP +> crashes, and therefore you have a WinXP problem? +>=20 +> Or do you mean that pg_dump takes 40 secs to +> complete under WinXP and 50 minutes under W2K and +> therefore you have a W2K problem? + +I think he is saying the time to dump does not take more than 40 +seconds, but I'm not sure. +=20 +> In fact, either 15MB/40secs=3D 375KBps or +> 200MB/40secs=3D 5MBps is _slow_, so there's a problem under either=20 +> platform! + +5 mb/sec dump output from psql is not terrible or even bad, depending on +hardware. + +> >not pass of 3%. +> Assuming Win XP completes the dump, the first thing to do is *don't=20 +> use W2K* + +XP is not a server platform. Next level up is 2003 server. Many +organizations still have 2k deployed. About half of my servers still +run it. Anyways, the 2k/xp issue does not explain why there is a +performance problem. + +> M$ has stopped supporting it in anything but absolutely minimum=20 +> fashion anyway. +> _If_ you are going to use an M$ OS you should be using WinXP. (You +> want to pay licensing fees for your OS, but you are using free DB SW? + +> Huh? If you are trying to save $$$, use Open Source SW like Linux +> or *BSD. pg will perform better under it, and it's cheaper!) + +I would like to see some benchmarks supporting those claims. No comment +on licensing issue, but there are many other factors in considering +server platform than licensing costs. That said, there were several +win32 specific pg performance issues that were rolled up into the 8.1 +release. So for win32 you definitely want to be running 8.1. +=20 +> Assuming that for some reason you can't/won't +> migrate to a non-M$ OS, the next problem is the +> slow HD IO you are getting under WinXP. + +Problem is almost certainly not related to disk unless there is a +imminent disk failure. Could be TCP/IP issue (are you running pg_dump +from remote box?), or possibly a network driver issue or some other +weird software issue. Can you determine if disk is running normally +with respect to other applications? Is this a fresh win2k install? A +LSP, virus scanner, backup software, or some other garbage can really +ruin your day. + +Merlin + + +From pgsql-performance-owner@postgresql.org Wed Nov 30 18:13:14 2005 +X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org +Received: from localhost (av.hub.org [200.46.204.144]) + by postgresql.org (Postfix) with ESMTP id 224179DCB0D + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 18:13:13 -0400 (AST) +Received: from postgresql.org ([200.46.204.71]) + by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) + with ESMTP id 17686-10 + for <pgsql-performance-postgresql.org@localhost.postgresql.org>; + Wed, 30 Nov 2005 18:13:12 -0400 (AST) +X-Greylist: from auto-whitelisted by SQLgrey- +Received: from Herge.rcsinc.local (mail.rcsonline.com [70.89.208.142]) + by postgresql.org (Postfix) with ESMTP id 4336F9DCAB5 + for <pgsql-performance@postgresql.org>; + Wed, 30 Nov 2005 18:13:07 -0400 (AST) +Content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-MimeOLE: Produced By Microsoft Exchange V6.5 +Subject: Re: RES: pg_dump slow +Date: Wed, 30 Nov 2005 17:13:08 -0500 +Message-ID: <6EE64EF3AB31D5448D0007DD34EEB3417DD9CC@Herge.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: RES: [PERFORM] pg_dump slow +Thread-Index: AcX18fRf1JsLmgu6Q3CN2R7scBGU/AABkDrA +From: "Merlin Moncure" <merlin.moncure@rcsonline.com> +To: "Ron" <rjpeace@earthlink.net> +Cc: <pgsql-performance@postgresql.org>, + "Franklin Haut" <franklin.haut@gmail.com> +X-Virus-Scanned: by amavisd-new at hub.org +X-Spam-Status: No, score=0 required=5 tests=[none] +X-Spam-Score: 0 +X-Spam-Level: +X-Archive-Number: 200511/562 +X-Sequence-Number: 15819 + +> By default W2K systems often had a default TCP/IP packet size of 576B +> and a tiny RWIN. Optimal for analog modems talking over noisy POTS +> lines, but horrible for everything else + +wrong. default MTU for windows 2000 server is 1500, as was NT4. +http://support.microsoft.com/?id=3D140375 + +However tweaking rwin is certainly something to look at. + +> >If you're happy that doesn't affect you then I'd look at the disk +> >system - perhaps XP has newer drivers than Win2k. +> I'll reiterate: Do _not_ run a production DB server on W2K. M$ has +> obsoleted the platform and that it is not supported _nor_ any of +> reliable, secure, etc. etc. + +wrong again. WIN2k gets free security hotfixes and paid support until +2010. +http://www.microsoft.com/windows2000/support/lifecycle/ +=20 +> A W2K based DB server, particularly one with a connection to the +> Internet, is a ticking time bomb at this point. +> Get off W2K as a production platform ASAP. Take to your +> CEO/Dean/whatever you call your Fearless Leader if you have to. + +wrong again!! There is every reason to believe win2k is *more* secure +than win2003 sever because it is a more stable platform. This of course +depends on what other services are running, firewall issues, etc etc. + +>> Economically and probably performance wise, it's best to use an Open +> Source OS like Linux or *BSD. However, if you must use M$, at least +> use OS's that M$ is actively supporting. + +I encourage use of open source software. However encouraging other +people to spontaneously switch hardware/software platforms (especially +when they just stated when win2k is a requirement) is just or at least +not helpful. +=20 +> Despite M$ marketing propaganda and a post in this thread to the +> contrary, you =3DCAN=3D often run a production DB server under WinXP = +and +> not pay M$ their usurious licensing fees for W2003 Server or any of +> their other products with "server" in the title. How much RAM and + +you are on a roll here. You must not be aware of 10 connection limit +for win2k pro and winxp pro. + +http://winhlp.com/WxConnectionLimit.htm + +There are hackerish ways of getting around this which are illegal. +Cheating to get around this by pooling connections via tcp proxy for +example is also against EULA (and, in my opinion, unethical). + +> how many CPUs you want in your DB server is the main issue. For a +> 1P, <=3D 4GB RAM vanilla box, WinXp will work just fine. + +Now, who is guilty of propaganda here? Also, your comments regarding +hard disks while correct in the general sense are not helpful. This is +clearly not a disk bandwidth problem. + +> >What do the MS performance-charts show is happening? Specifically, +> >CPU and disk I/O. +> His original post said ~3% CPU under W2K and ~70% CPU under WinXP + +Slow performance in extraction of bytea column strongly suggests tcp/ip. +issue. I bet if you blanked out bytea column pg_dump will be fast.=20 + +Franlin: are you making pg_dump from local or remote box and is this a +clean install? Try fresh patched win2k install and see what happens. + +Merlin +