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Restructure planning of nestloop inner indexscans so that the set of usable

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joinclauses is determined accurately for each join.  Formerly, the code only
considered joinclauses that used all of the rels from the outer side of the
join; thus for example
	FROM (a CROSS JOIN b) JOIN c ON (c.f1 = a.x AND c.f2 = b.y)
could not exploit a two-column index on c(f1,f2), since neither of the
qual clauses would be in the joininfo list it looked in.  The new code does
this correctly, and also is able to eliminate redundant clauses, thus fixing
the problem noted 24-Oct-02 by Hans-Jürgen Schönig.
This commit is contained in:
Tom Lane
2002-11-24 21:52:15 +00:00
parent 6bfc09baf4
commit 04c8785c7b
19 changed files with 742 additions and 579 deletions
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15
src/backend/optimizer/plan/initsplan.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.76 2002/11/19 23:21:58 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.77 2002/11/24 21:52:14 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -577,15 +577,12 @@ distribute_qual_to_rels(Query *root, Node *clause,
* the relid list. Set additional RestrictInfo fields for
* joining.
*
* We don't bother setting the merge/hashjoin info if we're not going
* to need it. We do want to know about mergejoinable ops in any
* potential equijoin clause (see later in this routine), and we
* ignore enable_mergejoin if isouterjoin is true, because
* mergejoin is the only implementation we have for full and right
* outer joins.
* We don't bother setting the hashjoin info if we're not going
* to need it. We do want to know about mergejoinable ops in all
* cases, however, because we use mergejoinable ops for other
* purposes such as detecting redundant clauses.
*/
if (enable_mergejoin || isouterjoin || can_be_equijoin)
check_mergejoinable(restrictinfo);
check_mergejoinable(restrictinfo);
if (enable_hashjoin)
check_hashjoinable(restrictinfo);