input: [Name] is_deterministic [Description] If the function is declared immutable (called deterministic in the SQL standard), then YES, else NO. (You cannot query the other volatility levels available in PostgreSQL through the information schema.) [Data Type] 
output: yes_or_no
options: s q l _ i d e n t i f i e r
options: c h a r a c t e r _ d a t a
options: c a r d i n a l _ n u m b e r
options: y e s _ o r _ n o
options: t i m e _ s t a m p