Simon Riggs <simon@xxxxxxxxxxxxxxx> writes: > On Mon, 2009-10-19 at 13:43 -0400, Tom Lane wrote: >> Simon Riggs <simon@xxxxxxxxxxxxxxx> writes: >>> I think we should have a 4th class of functions, >>> volatile-without-side-effects (better name needed, obviously). >> >> What for? There wouldn't be that many, I think. random() and >> clock_timestamp(), yeah, but most volatile user-defined functions >> are either volatile-with-side-effects or misdeclared. > Read only vs. read write? Most read-only functions are stable or even immutable. I don't say that there's zero usefulness in a fourth class, but I do say it's unlikely to be worth the trouble. (The only reason it even came up in this connection is that the default for user-defined functions is "volatile" which would defeat this optimization ... but we could hardly make the default anything else.) regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
