From fb9e56eea11a970e574260b82d6b05b4fe5a4308 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 19 Aug 2006 02:48:53 +0000 Subject: Suppress subquery pullup/pushdown when a subquery contains volatile functions in its targetlist, to avoid introducing multiple evaluations of volatile functions that textually appear only once. This is a slightly tighter version of Jaime Casanova's recent patch. --- src/backend/optimizer/prep/prepjointree.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'src/backend/optimizer/prep/prepjointree.c') diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c index ef92d9d3c9f..bea7c03a739 100644 --- a/src/backend/optimizer/prep/prepjointree.c +++ b/src/backend/optimizer/prep/prepjointree.c @@ -15,7 +15,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.42 2006/08/12 20:05:55 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.43 2006/08/19 02:48:53 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -656,6 +656,15 @@ is_simple_subquery(Query *subquery) if (expression_returns_set((Node *) subquery->targetList)) return false; + /* + * Don't pull up a subquery that has any volatile functions in its + * targetlist. Otherwise we might introduce multiple evaluations of + * these functions, if they get copied to multiple places in the upper + * query, leading to surprising results. + */ + if (contain_volatile_functions((Node *) subquery->targetList)) + return false; + /* * Hack: don't try to pull up a subquery with an empty jointree. * query_planner() will correctly generate a Result plan for a jointree -- cgit v1.2.3