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Correct bug in best_innerjoin(): it should check all the

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rels that the inner path needs to join to, but it was only checking for
the first one.  Failure could only have been observed with an OR-clause
that mentions 3 or more tables, and then only if the bogus path was
actually selected as cheapest ...
This commit is contained in:
Tom Lane
1999-07-27 06:23:12 +00:00
parent 2f30d5a34a
commit b62fdc13f0
3 changed files with 64 additions and 53 deletions
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19
src/backend/optimizer/path/joinpath.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.41 1999/07/16 04:59:15 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.42 1999/07/27 06:23:12 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -147,13 +147,14 @@ update_rels_pathlist_for_joins(Query *root, List *joinrels)
/*
* best_innerjoin
* Find the cheapest index path that has already been identified by
* (indexable_joinclauses) as being a possible inner path for the given
* outer relation in a nestloop join.
* indexable_joinclauses() as being a possible inner path for the given
* outer relation(s) in a nestloop join.
*
* 'join_paths' is a list of join nodes
* 'outer_relid' is the relid of the outer join relation
* 'join_paths' is a list of potential inner indexscan join paths
* 'outer_relids' is the relid list of the outer join relation
*
* Returns the pathnode of the selected path.
* Returns the pathnode of the best path, or NULL if there's no
* usable path.
*/
static Path *
best_innerjoin(List *join_paths, Relids outer_relids)
@ -165,7 +166,11 @@ best_innerjoin(List *join_paths, Relids outer_relids)
{
Path *path = (Path *) lfirst(join_path);
if (intMember(lfirsti(path->joinid), outer_relids) &&
/* path->joinid is the set of base rels that must be part of
* outer_relids in order to use this inner path, because those
* rels are used in the index join quals of this inner path.
*/
if (is_subset(path->joinid, outer_relids) &&
(cheapest == NULL ||
path_is_cheaper(path, cheapest)))
cheapest = path;