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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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14
src/include/optimizer/joininfo.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: joininfo.h,v 1.22 2003/01/20 18:55:04 tgl Exp $
* $Id: joininfo.h,v 1.23 2003/01/24 03:58:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -16,7 +16,15 @@
#include "nodes/relation.h"
extern JoinInfo *find_joininfo_node(RelOptInfo *this_rel, List *join_relids);
extern JoinInfo *make_joininfo_node(RelOptInfo *this_rel, List *join_relids);
extern JoinInfo *find_joininfo_node(RelOptInfo *this_rel, Relids join_relids);
extern JoinInfo *make_joininfo_node(RelOptInfo *this_rel, Relids join_relids);
extern void add_join_clause_to_rels(Query *root,
RestrictInfo *restrictinfo,
Relids join_relids);
extern void remove_join_clause_from_rels(Query *root,
RestrictInfo *restrictinfo,
Relids join_relids);
#endif /* JOININFO_H */

4
src/include/optimizer/paths.h
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@@ -8,7 +8,7 @@
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: paths.h,v 1.63 2002/12/16 21:30:30 tgl Exp $
* $Id: paths.h,v 1.64 2003/01/24 03:58:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -17,6 +17,7 @@
#include "nodes/relation.h"
/* default GEQO threshold (default value for geqo_rels) */
/* If you change this, update backend/utils/misc/postgresql.sample.conf */
#define DEFAULT_GEQO_RELS 11
@@ -92,6 +93,7 @@ typedef enum
} PathKeysComparison;
extern void add_equijoined_keys(Query *root, RestrictInfo *restrictinfo);
extern bool exprs_known_equal(Query *root, Node *item1, Node *item2);
extern void generate_implied_equalities(Query *root);
extern List *canonicalize_pathkeys(Query *root, List *pathkeys);
extern PathKeysComparison compare_pathkeys(List *keys1, List *keys2);

10
src/include/optimizer/planmain.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: planmain.h,v 1.67 2003/01/20 18:55:05 tgl Exp $
* $Id: planmain.h,v 1.68 2003/01/24 03:58:44 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -57,9 +57,11 @@ extern Result *make_result(List *tlist, Node *resconstantqual, Plan *subplan);
extern void add_base_rels_to_query(Query *root, Node *jtnode);
extern void build_base_rel_tlists(Query *root, List *tlist);
extern Relids distribute_quals_to_rels(Query *root, Node *jtnode);
extern void process_implied_equality(Query *root, Node *item1, Node *item2,
Oid sortop1, Oid sortop2);
extern bool exprs_known_equal(Query *root, Node *item1, Node *item2);
extern void process_implied_equality(Query *root,
Node *item1, Node *item2,
Oid sortop1, Oid sortop2,
Relids item1_relids, Relids item2_relids,
bool delete_it);
/*
* prototypes for plan/setrefs.c