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When a relation has been proven empty by constraint exclusion, propagate that

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knowledge up through any joins it participates in.  We were doing that already
in some special cases but not in the general case.  Also, defend against zero
row estimates for the input relations in cost_mergejoin --- this fix may have
eliminated the only scenario in which that can happen, but be safe.  Per
report from Alex Solovey.
This commit is contained in:
Tom Lane
2008-03-24 21:53:04 +00:00
parent 2a346725ba
commit fd791e7b5a
5 changed files with 113 additions and 11 deletions
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4
src/backend/optimizer/path/allpaths.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.168 2008/01/11 04:02:18 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.169 2008/03/24 21:53:03 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -428,7 +428,7 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
* Build a dummy path for a relation that's been excluded by constraints
*
* Rather than inventing a special "dummy" path type, we represent this as an
* AppendPath with no members.
* AppendPath with no members (see also IS_DUMMY_PATH macro).
*/
static void
set_dummy_rel_pathlist(RelOptInfo *rel)