On Wed, Nov 24, 2010 at 21:52, Tom Lane <t...@sss.pgh.pa.us> wrote: > Bruce Momjian <br...@momjian.us> writes: >> Notice the to_date()'s were not converted to constants in EXPLAIN so >> they are evaluated for every row. to_date() is marked STABLE.
> No. This is per expectation. Only IMMUTABLE functions can be folded to > constants in advance of the query. This is something that has bit me in the past. I realize that STABLE functions cannot be constant-folded at planning-time. But are there good reasons why it cannot called only once at execution-time? As long as *only* STABLE or IMMUTABLE functions are used in a query, we can assume that settings like timezone won't change in the middle of the execution of a function, thus STABLE function calls can be collapsed -- right? Regards, Marti -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
