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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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3
src/backend/nodes/copyfuncs.c
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@ -15,7 +15,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.310 2005/06/28 05:08:56 tgl Exp $
* $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.311 2005/07/02 23:00:39 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1249,7 +1249,6 @@ _copyRestrictInfo(RestrictInfo *from)
COPY_NODE_FIELD(clause);
COPY_SCALAR_FIELD(is_pushed_down);
COPY_SCALAR_FIELD(valid_everywhere);
COPY_SCALAR_FIELD(can_join);
COPY_BITMAPSET_FIELD(clause_relids);
COPY_BITMAPSET_FIELD(required_relids);