From aca467b9b343dccd52a8c8da74ffcf70559fb468 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 24 Nov 2007 19:08:51 +0000 Subject: [PATCH] Save another little bit of planner overhead on simple queries, by having clauselist_selectivity skip some analysis that's useless when there's only one clause in the given list. Actually this can win even for not-so-simple queries, because we also apply clauselist_selectivity to sublists such as the quals matching an index; which are likely to have only a single entry even when the total query is quite complicated. --- src/backend/optimizer/path/clausesel.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/src/backend/optimizer/path/clausesel.c b/src/backend/optimizer/path/clausesel.c index f5ee929c56..dd4a27b96c 100644 --- a/src/backend/optimizer/path/clausesel.c +++ b/src/backend/optimizer/path/clausesel.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/path/clausesel.c,v 1.87 2007/08/31 23:35:22 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/path/clausesel.c,v 1.88 2007/11/24 19:08:51 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -100,6 +100,14 @@ clauselist_selectivity(PlannerInfo *root, RangeQueryClause *rqlist = NULL; ListCell *l; + /* + * If there's exactly one clause, then no use in trying to match up + * pairs, so just go directly to clause_selectivity(). + */ + if (list_length(clauses) == 1) + return clause_selectivity(root, (Node *) linitial(clauses), + varRelid, jointype); + /* * Initial scan over clauses. Anything that doesn't look like a potential * rangequery clause gets multiplied into s1 and forgotten. Anything that