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Take OUTER JOIN semantics into account when estimating the size of join

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relations.  It's not very bright, but at least it now knows that
A LEFT JOIN B must produce at least as many rows as are in A ...
This commit is contained in:
Tom Lane
2001-02-16 00:03:08 +00:00
parent ca71c66190
commit b29f68f611
5 changed files with 47 additions and 11 deletions
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6
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 1.31 2001/01/24 19:43:00 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.32 2001/02/16 00:03:08 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -152,6 +152,7 @@ find_join_rel(Query *root, Relids relids)
*
* 'outer_rel' and 'inner_rel' are relation nodes for the relations to be
* joined
* 'jointype': type of join (inner/outer)
* 'restrictlist_ptr': result variable. If not NULL, *restrictlist_ptr
* receives the list of RestrictInfo nodes that apply to this
* particular pair of joinable relations.
@ -163,6 +164,7 @@ RelOptInfo *
get_join_rel(Query *root,
RelOptInfo *outer_rel,
RelOptInfo *inner_rel,
JoinType jointype,
List **restrictlist_ptr)
{
List *joinrelids;
@ -252,7 +254,7 @@ get_join_rel(Query *root,
* Set estimates of the joinrel's size.
*/
set_joinrel_size_estimates(root, joinrel, outer_rel, inner_rel,
restrictlist);
jointype, restrictlist);
/*
* Add the joinrel to the query's joinrel list.