From 248182560c9577a7519cd4f817be560df7a53580 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 14 May 2001 20:25:00 +0000 Subject: [PATCH] Current implementation of FOR UPDATE has no hope of working correctly for relations on the nullable side of an OUTER JOIN. For now I think we'd better refuse such queries. --- src/backend/optimizer/plan/initsplan.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/src/backend/optimizer/plan/initsplan.c b/src/backend/optimizer/plan/initsplan.c index 5d67e02dac..c62fd5ecd7 100644 --- a/src/backend/optimizer/plan/initsplan.c +++ b/src/backend/optimizer/plan/initsplan.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.60 2001/05/07 00:43:21 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.61 2001/05/14 20:25:00 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -298,7 +298,8 @@ mark_baserels_for_outer_join(Query *root, Relids rels, Relids outerrels) foreach(relid, rels) { - RelOptInfo *rel = get_base_rel(root, lfirsti(relid)); + int relno = lfirsti(relid); + RelOptInfo *rel = get_base_rel(root, relno); /* * Since we do this bottom-up, any outer-rels previously marked @@ -306,6 +307,21 @@ mark_baserels_for_outer_join(Query *root, Relids rels, Relids outerrels) */ Assert(is_subseti(rel->outerjoinset, outerrels)); + /* + * Presently the executor cannot support FOR UPDATE marking of + * rels appearing on the nullable side of an outer join. + * (It's somewhat unclear what that would mean, anyway: what should + * we mark when a result row is generated from no element of the + * nullable relation?) So, complain if target rel is FOR UPDATE. + * It's sufficient to make this check once per rel, so do it only + * if rel wasn't already known nullable. + */ + if (rel->outerjoinset == NIL) + { + if (intMember(relno, root->rowMarks)) + elog(ERROR, "SELECT FOR UPDATE cannot be applied to the nullable side of an OUTER JOIN"); + } + rel->outerjoinset = outerrels; } }