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Teach planner about some cases where a restriction clause can be

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propagated inside an outer join.  In particular, given
LEFT JOIN ON (A = B) WHERE A = constant, we cannot conclude that
B = constant at the top level (B might be null instead), but we
can nonetheless put a restriction B = constant into the quals for
B's relation, since no inner-side rows not meeting that condition
can contribute to the final result.  Similarly, given
FULL JOIN USING (J) WHERE J = constant, we can't directly conclude
that either input J variable = constant, but it's OK to push such
quals into each input rel.  Per recent gripe from Kim Bisgaard.
Along the way, remove 'valid_everywhere' flag from RestrictInfo,
as on closer analysis it was not being used for anything, and was
defined backwards anyway.
This commit is contained in:
Tom Lane
2005-07-02 23:00:42 +00:00
parent ea1e2b948d
commit cc5e80b8d1
13 changed files with 424 additions and 114 deletions
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5
src/backend/optimizer/plan/createplan.c
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@@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.192 2005/06/10 22:25:36 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.193 2005/07/02 23:00:41 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -1176,8 +1176,7 @@ create_nestloop_plan(PlannerInfo *root,
List *bitmapclauses;
bitmapclauses =
make_restrictinfo_from_bitmapqual(innerpath->bitmapqual,
true, true);
make_restrictinfo_from_bitmapqual(innerpath->bitmapqual, true);
joinrestrictclauses =
select_nonredundant_join_clauses(root,
joinrestrictclauses,