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Fix an oversight in join-removal optimization: we have to check not only for

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plain Vars that are generated in the inner rel and used above the join, but
also for PlaceHolderVars.  Per report from Oleg K.
This commit is contained in:
Tom Lane
2010-03-22 13:57:16 +00:00
parent ecac5e6bfc
commit 8d3c4aa614
3 changed files with 89 additions and 2 deletions
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19
src/backend/optimizer/path/joinpath.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/joinpath.c,v 1.130 2010/02/26 02:00:44 momjian Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/joinpath.c,v 1.131 2010/03/22 13:57:15 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -192,7 +192,9 @@ clause_sides_match_join(RestrictInfo *rinfo, RelOptInfo *outerrel,
*
* This is true for a left join for which the join condition cannot match
* more than one inner-side row. (There are other possibly interesting
* cases, but we don't have the infrastructure to prove them.)
* cases, but we don't have the infrastructure to prove them.) We also
* have to check that the inner side doesn't generate any variables needed
* above the join.
*
* Note: there is no need to consider the symmetrical case of duplicating the
* right input, because add_paths_to_joinrel() will be called with each rel
@ -245,6 +247,19 @@ join_is_removable(PlannerInfo *root,
return false;
}
/*
* Similarly check that the inner rel doesn't produce any PlaceHolderVars
* that will be used above the join.
*/
foreach(l, root->placeholder_list)
{
PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(l);
if (bms_is_subset(phinfo->ph_eval_at, innerrel->relids) &&
!bms_is_subset(phinfo->ph_needed, joinrel->relids))
return false;
}
/*
* Search for mergejoinable clauses that constrain the inner rel against
* either the outer rel or a pseudoconstant. If an operator is