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Modify planner's implied-equality-deduction code so that when a set

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of known-equal expressions includes any constant expressions (including
Params from outer queries), we actively suppress any 'var = var'
clauses that are or could be deduced from the set, generating only the
deducible 'var = const' clauses instead.  The idea here is to push down
the restrictions implied by the equality set to base relations whenever
possible.  Once we have applied the 'var = const' clauses, the 'var = var'
clauses are redundant, and should be suppressed both to save work at
execution and to avoid double-counting restrictivity.
This commit is contained in:
Tom Lane
2003-01-24 03:58:44 +00:00
parent ef7422510e
commit f5e83662d0
12 changed files with 395 additions and 168 deletions
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13
src/backend/optimizer/util/relnode.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.44 2003/01/20 18:54:56 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.45 2003/01/24 03:58:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -549,14 +549,19 @@ subbuild_joinrel_joinlist(RelOptInfo *joinrel,
/*
* These clauses are still join clauses at this level, so find
* or make the appropriate JoinInfo item for the joinrel, and
* add the clauses to it (eliminating duplicates).
* add the clauses to it, eliminating duplicates. (Since
* RestrictInfo nodes are normally multiply-linked rather than
* copied, pointer equality should be a sufficient test. If
* two equal() nodes should happen to sneak in, no great harm
* is done --- they'll be detected by redundant-clause testing
* when they reach a restriction list.)
*/
JoinInfo *new_joininfo;
new_joininfo = make_joininfo_node(joinrel, new_unjoined_relids);
new_joininfo->jinfo_restrictinfo =
set_union(new_joininfo->jinfo_restrictinfo,
joininfo->jinfo_restrictinfo);
set_ptrUnion(new_joininfo->jinfo_restrictinfo,
joininfo->jinfo_restrictinfo);
}
}
}