2009/10/21 Merlin Moncure <mmonc...@gmail.com>: > On Tue, Oct 20, 2009 at 5:12 PM, Pavel Stehule <pavel.steh...@gmail.com> > wrote: >>> [ shrug... ] There are other possible reasons why the planner would >>> fail to flatten a subquery, but none of them apply to the example you >>> showed. And your example function *was* VOLATILE, by default. >> >> I checked this on 8.5 and function is evaluated more time although is >> immutable. >> >> postgres=# create or replace function foo(out a int, out b int) >> returns record as $$ >> begin >> raise notice 'start foo'; >> a := 10; b := 20; >> return; >> end; >> $$ language plpgsql immutable; >> CREATE FUNCTION >> >> postgres=# select (foo()).*; > > This is because select (func()).* is expanded to mean: > select func(f1), func(f2) ... func(fn); > > This is a general issue with '*' because in postgres it means: > 'evaluate me for each field of me', not 'return all fields of me'. I > don't think our behavior in this regard is correct (afaict i'm in the > minority though). >
I understand to this mechanism. This is only correction some previous messages. This behave isn't depend on function immutability or volatility. But I agree with you, so this is really problem - it is very silent. Maybe we could to raise some warning or we could to move funccall to subselect like SELECT (foo()).* to SELECT ( (SELECT foo()) ).* Regards Pavel Stehule > merlin > -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
