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Test for whether a previous IN join restricts the current join was too

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strict, per discussion with Dennis Haney.
Also, rearrange the preceding tests to avoid redundancy.
This commit is contained in:
Tom Lane 2004-03-08 17:20:17 +00:00
parent 0bdce30f6b
commit 7998e8ca6a
1 changed files with 31 additions and 21 deletions
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52
src/backend/optimizer/path/joinrels.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.66 2004/01/24 00:37:28 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.67 2004/03/08 17:20:17 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -483,35 +483,45 @@ make_join_rel(Query *root, RelOptInfo *rel1, RelOptInfo *rel2,
InClauseInfo *ininfo = (InClauseInfo *) lfirst(l);
/*
* Cannot join if proposed join contains part, but only part,
* of the RHS, *and* it contains rels not in the RHS.
* This IN clause is not relevant unless its RHS overlaps the
* proposed join. (Check this first as a fast path for dismissing
* most irrelevant INs quickly.)
*/
if (bms_overlap(ininfo->righthand, joinrelids) &&
!bms_is_subset(ininfo->righthand, joinrelids) &&
!bms_is_subset(joinrelids, ininfo->righthand))
if (!bms_overlap(ininfo->righthand, joinrelids))
continue;
/*
* If we are still building the IN clause's RHS, then this IN
* clause isn't relevant yet.
*/
if (bms_is_subset(joinrelids, ininfo->righthand))
continue;
/*
* Cannot join if proposed join contains rels not in the RHS
* *and* contains only part of the RHS. We must build the
* complete RHS (subselect's join) before it can be joined to
* rels outside the subselect.
*/
if (!bms_is_subset(ininfo->righthand, joinrelids))
{
bms_free(joinrelids);
return NULL;
}
/*
* No issue unless we are looking at a join of the IN's RHS to
* other stuff.
* At this point we are considering a join of the IN's RHS to
* some other rel(s).
*
* If we already joined IN's RHS to any other rels in either
* input path, then this join is not constrained (the necessary
* work was done at the lower level where that join occurred).
*/
if (!(bms_is_subset(ininfo->righthand, joinrelids) &&
!bms_equal(ininfo->righthand, joinrelids)))
if (bms_is_subset(ininfo->righthand, rel1->relids) &&
!bms_equal(ininfo->righthand, rel1->relids))
continue;
/*
* If we already joined IN's RHS to any part of its LHS in
* either input path, then this join is not constrained (the
* necessary work was done at a lower level).
*/
if (bms_overlap(ininfo->lefthand, rel1->relids) &&
bms_is_subset(ininfo->righthand, rel1->relids))
continue;
if (bms_overlap(ininfo->lefthand, rel2->relids) &&
bms_is_subset(ininfo->righthand, rel2->relids))
if (bms_is_subset(ininfo->righthand, rel2->relids) &&
!bms_equal(ininfo->righthand, rel2->relids))
continue;
/*