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Fix for bug #795: two clauses that seem redundant are not really, if

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one is pushed down into an outer join and the other is not.
This commit is contained in:
Tom Lane 2002-10-12 22:24:49 +00:00
parent 8031b066fa
commit 5bb46e7cd0
1 changed files with 18 additions and 6 deletions
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24
src/backend/optimizer/util/relnode.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.39 2002/09/04 20:31:22 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.40 2002/10/12 22:24:49 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -28,7 +28,8 @@ static List *new_join_tlist(List *tlist, int first_resdomno);
static List *build_joinrel_restrictlist(Query *root,
RelOptInfo *joinrel,
RelOptInfo *outer_rel,
RelOptInfo *inner_rel);
RelOptInfo *inner_rel,
JoinType jointype);
static void build_joinrel_joinlist(RelOptInfo *joinrel,
RelOptInfo *outer_rel,
RelOptInfo *inner_rel);
@ -334,7 +335,8 @@ build_join_rel(Query *root,
*restrictlist_ptr = build_joinrel_restrictlist(root,
joinrel,
outer_rel,
inner_rel);
inner_rel,
jointype);
return joinrel;
}
@ -419,7 +421,8 @@ build_join_rel(Query *root,
restrictlist = build_joinrel_restrictlist(root,
joinrel,
outer_rel,
inner_rel);
inner_rel,
jointype);
if (restrictlist_ptr)
*restrictlist_ptr = restrictlist;
build_joinrel_joinlist(joinrel, outer_rel, inner_rel);
@ -508,6 +511,7 @@ new_join_tlist(List *tlist,
* 'joinrel' is a join relation node
* 'outer_rel' and 'inner_rel' are a pair of relations that can be joined
* to form joinrel.
* 'jointype' is the type of join used.
*
* build_joinrel_restrictlist() returns a list of relevant restrictinfos,
* whereas build_joinrel_joinlist() stores its results in the joinrel's
@ -522,7 +526,8 @@ static List *
build_joinrel_restrictlist(Query *root,
RelOptInfo *joinrel,
RelOptInfo *outer_rel,
RelOptInfo *inner_rel)
RelOptInfo *inner_rel,
JoinType jointype)
{
List *result = NIL;
List *rlist;
@ -553,6 +558,11 @@ build_joinrel_restrictlist(Query *root,
* one clause that checks equality between any set member on the left
* and any member on the right; by transitivity, all the rest are then
* equal.
*
* Weird special case: if we have two clauses that seem redundant
* except one is pushed down into an outer join and the other isn't,
* then they're not really redundant, because one constrains the
* joined rows after addition of null fill rows, and the other doesn't.
*/
foreach(item, rlist)
{
@ -576,7 +586,9 @@ build_joinrel_restrictlist(Query *root,
if (oldrinfo->mergejoinoperator != InvalidOid &&
rinfo->left_pathkey == oldrinfo->left_pathkey &&
rinfo->right_pathkey == oldrinfo->right_pathkey)
rinfo->right_pathkey == oldrinfo->right_pathkey &&
(rinfo->ispusheddown == oldrinfo->ispusheddown ||
!IS_OUTER_JOIN(jointype)))
{
redundant = true;
break;