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My recent fix for semijoin planning didn't actually work for a semijoin with a 

RHS that can't be unique-ified --- join_is_legal has to check that before
deciding to build a join, else we'll have an unimplementable joinrel.
Per report from Greg Stark.
This commit is contained in:
Tom Lane 2008-11-28 19:29:07 +00:00
parent 5f77b1ac51
commit 213256cfa9
1 changed files with 12 additions and 5 deletions
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17
src/backend/optimizer/path/joinrels.c
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@ -8,7 +8,7 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.95 2008/11/22 22:47:06 tgl Exp $ * $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.96 2008/11/28 19:29:07 tgl Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -420,11 +420,13 @@ join_is_legal(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
reversed = true; reversed = true;
} }
else if (sjinfo->jointype == JOIN_SEMI && else if (sjinfo->jointype == JOIN_SEMI &&
bms_equal(sjinfo->syn_righthand, rel2->relids)) bms_equal(sjinfo->syn_righthand, rel2->relids) &&
create_unique_path(root, rel2, rel2->cheapest_total_path,
sjinfo) != NULL)
{ {
/* /*
* For a semijoin, we can join the RHS to anything else by * For a semijoin, we can join the RHS to anything else by
* unique-ifying the RHS. * unique-ifying the RHS (if the RHS can be unique-ified).
*/ */
if (match_sjinfo) if (match_sjinfo)
return false; /* invalid join path */ return false; /* invalid join path */
@ -432,7 +434,9 @@ join_is_legal(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
reversed = false; reversed = false;
} }
else if (sjinfo->jointype == JOIN_SEMI && else if (sjinfo->jointype == JOIN_SEMI &&
bms_equal(sjinfo->syn_righthand, rel1->relids)) bms_equal(sjinfo->syn_righthand, rel1->relids) &&
create_unique_path(root, rel1, rel1->cheapest_total_path,
sjinfo) != NULL)
{ {
/* Reversed semijoin case */ /* Reversed semijoin case */
if (match_sjinfo) if (match_sjinfo)
@ -664,7 +668,10 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2)
/* /*
* If we know how to unique-ify the RHS and one input rel is * If we know how to unique-ify the RHS and one input rel is
* exactly the RHS (not a superset) we can consider unique-ifying * exactly the RHS (not a superset) we can consider unique-ifying
* it and then doing a regular join. * it and then doing a regular join. (The create_unique_path
* check here is probably redundant with what join_is_legal did,
* but if so the check is cheap because it's cached. So test
* anyway to be sure.)
*/ */
if (bms_equal(sjinfo->syn_righthand, rel2->relids) && if (bms_equal(sjinfo->syn_righthand, rel2->relids) &&
create_unique_path(root, rel2, rel2->cheapest_total_path, create_unique_path(root, rel2, rel2->cheapest_total_path,