From ad511a3ff352e2b6ef94791bb27b4b670a8dcb96 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 11 Nov 2001 19:18:54 +0000
Subject: [PATCH] sort_inner_and_outer needs a check to ensure that it's
consumed all the mergeclauses in RIGHT/FULL join cases, just like the other
routines have. I'm not quite sure why I thought it didn't need one --- but
Nick Fankhauser's recent bug report proves that it does.
---
src/backend/optimizer/path/joinpath.c | 29 ++++++++++++++++++++++++++-
1 file changed, 28 insertions(+), 1 deletion(-)
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c
index 15bb56757d1..4d60569e7ef 100644
--- a/src/backend/optimizer/path/joinpath.c
+++ b/src/backend/optimizer/path/joinpath.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.66 2001/10/25 05:49:32 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.67 2001/11/11 19:18:54 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -150,9 +150,31 @@ sort_inner_and_outer(Query *root,
List *mergeclause_list,
JoinType jointype)
{
+ bool useallclauses;
List *all_pathkeys;
List *i;
+ /*
+ * If we are doing a right or full join, we must use *all* the
+ * mergeclauses as join clauses, else we will not have a valid plan.
+ */
+ switch (jointype)
+ {
+ case JOIN_INNER:
+ case JOIN_LEFT:
+ useallclauses = false;
+ break;
+ case JOIN_RIGHT:
+ case JOIN_FULL:
+ useallclauses = true;
+ break;
+ default:
+ elog(ERROR, "sort_inner_and_outer: unexpected join type %d",
+ (int) jointype);
+ useallclauses = false; /* keep compiler quiet */
+ break;
+ }
+
/*
* Each possible ordering of the available mergejoin clauses will
* generate a differently-sorted result path at essentially the same
@@ -212,6 +234,11 @@ sort_inner_and_outer(Query *root,
mergeclause_list);
Assert(cur_mergeclauses != NIL);
+ /* Forget it if can't use all the clauses in right/full join */
+ if (useallclauses &&
+ length(cur_mergeclauses) != length(mergeclause_list))
+ continue;
+
/*
* Build sort pathkeys for both sides.
*
--
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