From 4df8de7a682e98be2b9072458bb9e77513f53c47 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 24 Oct 2006 17:50:22 +0000
Subject: [PATCH] Fix check for whether a clauseless join has to be forced in
the presence of outer joins. Originally it was only looking for overlap of
the righthand side of a left join, but we have to do it on the lefthand side
too. Per example from Jean-Pierre Pelletier.
---
src/backend/optimizer/geqo/geqo_eval.c | 20 +++++++++++++-------
src/backend/optimizer/path/joinrels.c | 16 ++++++++++++----
2 files changed, 25 insertions(+), 11 deletions(-)
diff --git a/src/backend/optimizer/geqo/geqo_eval.c b/src/backend/optimizer/geqo/geqo_eval.c
index 2d2f5e68268..240672edaf5 100644
--- a/src/backend/optimizer/geqo/geqo_eval.c
+++ b/src/backend/optimizer/geqo/geqo_eval.c
@@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/backend/optimizer/geqo/geqo_eval.c,v 1.80 2006/03/05 15:58:28 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/geqo/geqo_eval.c,v 1.81 2006/10/24 17:50:22 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -262,23 +262,29 @@ desirable_join(PlannerInfo *root,
return true;
/*
- * Join if the rels are members of the same outer-join RHS. This is needed
- * to improve the odds that we will find a valid solution in a case where
- * an OJ RHS has a clauseless join.
+ * Join if the rels are members of the same outer-join side. This is
+ * needed to ensure that we can find a valid solution in a case where
+ * an OJ contains a clauseless join.
*/
foreach(l, root->oj_info_list)
{
OuterJoinInfo *ojinfo = (OuterJoinInfo *) lfirst(l);
+ /* ignore full joins --- other mechanisms preserve their ordering */
+ if (ojinfo->is_full_join)
+ continue;
if (bms_is_subset(outer_rel->relids, ojinfo->min_righthand) &&
bms_is_subset(inner_rel->relids, ojinfo->min_righthand))
return true;
+ if (bms_is_subset(outer_rel->relids, ojinfo->min_lefthand) &&
+ bms_is_subset(inner_rel->relids, ojinfo->min_lefthand))
+ return true;
}
/*
- * Join if the rels are members of the same IN sub-select. This is needed
- * to improve the odds that we will find a valid solution in a case where
- * an IN sub-select has a clauseless join.
+ * Join if the rels are members of the same IN sub-select. This is needed
+ * to ensure that we can find a valid solution in a case where an IN
+ * sub-select has a clauseless join.
*/
foreach(l, root->in_info_list)
{
diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c
index bed9db50430..17b5f31915a 100644
--- a/src/backend/optimizer/path/joinrels.c
+++ b/src/backend/optimizer/path/joinrels.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.80 2006/10/04 00:29:54 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.81 2006/10/24 17:50:22 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -87,9 +87,9 @@ make_rels_by_joins(PlannerInfo *root, int level, List **joinrels)
/*
* An exception occurs when there is a clauseless join inside a
- * construct that restricts join order, i.e., an outer join RHS or
+ * construct that restricts join order, i.e., an outer join or
* an IN (sub-SELECT) construct. Here, the rel may well have join
- * clauses against stuff outside the OJ RHS or IN sub-SELECT, but
+ * clauses against stuff outside its OJ side or IN sub-SELECT, but
* the clauseless join *must* be done before we can make use of
* those join clauses. So do the clauseless join bit.
*
@@ -331,7 +331,7 @@ make_rels_by_clauseless_joins(PlannerInfo *root,
/*
* has_join_restriction
* Detect whether the specified relation has join-order restrictions
- * due to being inside an OJ RHS or an IN (sub-SELECT).
+ * due to being inside an outer join or an IN (sub-SELECT).
*/
static bool
has_join_restriction(PlannerInfo *root, RelOptInfo *rel)
@@ -342,8 +342,16 @@ has_join_restriction(PlannerInfo *root, RelOptInfo *rel)
{
OuterJoinInfo *ojinfo = (OuterJoinInfo *) lfirst(l);
+ /* ignore full joins --- other mechanisms preserve their ordering */
+ if (ojinfo->is_full_join)
+ continue;
+ /* anything inside the RHS is definitely restricted */
if (bms_is_subset(rel->relids, ojinfo->min_righthand))
return true;
+ /* if it's a proper subset of the LHS, it's also restricted */
+ if (bms_is_subset(rel->relids, ojinfo->min_lefthand) &&
+ !bms_equal(rel->relids, ojinfo->min_lefthand))
+ return true;
}
foreach(l, root->in_info_list)
--
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