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

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.

4 files changed, 22 insertions, 9 deletions

diff --git a/src/include/nodes/pg_list.h b/src/include/nodes/pg_list.h
index d3b01b7fed0..56a66409161 100644
--- a/src/include/nodes/pg_list.h
+++ b/src/include/nodes/pg_list.h
@@ -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);
diff --git a/src/include/optimizer/joininfo.h b/src/include/optimizer/joininfo.h
index 37131b722d2..6fd806bbaf1 100644
--- a/src/include/optimizer/joininfo.h
+++ b/src/include/optimizer/joininfo.h
@@ -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 */
diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index 7ed5b403a87..76285bac408 100644
--- a/src/include/optimizer/paths.h
+++ b/src/include/optimizer/paths.h
@@ -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);
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index cf9c2ddeb64..399b3bb1310 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -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