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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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3
src/include/nodes/pg_list.h
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@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: pg_list.h,v 1.31 2003/01/20 18:55:04 tgl Exp $
* $Id: pg_list.h,v 1.32 2003/01/24 03:58:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -141,6 +141,7 @@ extern List *set_differencei(List *list1, List *list2);
extern List *lreverse(List *l);
extern List *set_union(List *list1, List *list2);
extern List *set_unioni(List *list1, List *list2);
extern List *set_ptrUnion(List *list1, List *list2);
extern List *set_intersecti(List *list1, List *list2);
extern bool equali(List *list1, List *list2);