Separate predicate-testing code out of indxpath.c, making it a module

in its own right.  As proposed by Simon Riggs, but with some editorializing
of my own.

src/backend/optimizer/plan/createplan.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.191 2005/06/05 22:32:55 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.192 2005/06/10 22:25:36 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -22,9 +22,9 @@
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
-#include "optimizer/paths.h"
 #include "optimizer/plancat.h"
 #include "optimizer/planmain.h"
+#include "optimizer/predtest.h"
 #include "optimizer/restrictinfo.h"
 #include "optimizer/tlist.h"
 #include "optimizer/var.h"
@@ -782,8 +782,8 @@ create_indexscan_plan(PlannerInfo *root,
 	 * spot duplicate RestrictInfos, so we try that first.  In some situations
 	 * (particularly with OR'd index conditions) we may have scan_clauses
 	 * that are not equal to, but are logically implied by, the index quals;
-	 * so we also try a pred_test() check to see if we can discard quals
-	 * that way.
+	 * so we also try a predicate_implied_by() check to see if we can discard
+	 * quals that way.
 	 *
 	 * While at it, we strip off the RestrictInfos to produce a list of
 	 * plain expressions.
@@ -796,7 +796,8 @@ create_indexscan_plan(PlannerInfo *root,
 		Assert(IsA(rinfo, RestrictInfo));
 		if (list_member_ptr(nonlossy_indexquals, rinfo))
 			continue;
-		if (pred_test(list_make1(rinfo->clause), nonlossy_indexquals))
+		if (predicate_implied_by(list_make1(rinfo->clause),
+								 nonlossy_indexquals))
 			continue;
 		qpqual = lappend(qpqual, rinfo->clause);
 	}
@@ -878,7 +879,7 @@ create_bitmap_scan_plan(PlannerInfo *root,
 	 * clauses, so we try that first.  In some situations (particularly with
 	 * OR'd index conditions) we may have scan_clauses that are not equal to,
 	 * but are logically implied by, the index quals; so we also try a
-	 * pred_test() check to see if we can discard quals that way.
+	 * predicate_implied_by() check to see if we can discard quals that way.
 	 */
 	qpqual = NIL;
 	foreach(l, scan_clauses)
@@ -887,7 +888,8 @@ create_bitmap_scan_plan(PlannerInfo *root,
 
 		if (list_member(indexquals, clause))
 			continue;
-		if (pred_test(list_make1(clause), indexquals))
+		if (predicate_implied_by(list_make1(clause),
+								 indexquals))
 			continue;
 		qpqual = lappend(qpqual, clause);
 	}

src/backend/optimizer/util/Makefile

@@ -4,7 +4,7 @@
 #    Makefile for optimizer/util
 #
 # IDENTIFICATION
-#    $PostgreSQL: pgsql/src/backend/optimizer/util/Makefile,v 1.15 2003/11/29 19:51:51 pgsql Exp $
+#    $PostgreSQL: pgsql/src/backend/optimizer/util/Makefile,v 1.16 2005/06/10 22:25:36 tgl Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -12,8 +12,8 @@ subdir = src/backend/optimizer/util
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = restrictinfo.o clauses.o plancat.o \
-       joininfo.o pathnode.o relnode.o tlist.o var.o
+OBJS = clauses.o joininfo.o pathnode.o plancat.o predtest.o \
+       relnode.o restrictinfo.o tlist.o var.o
 
 all: SUBSYS.o
 

src/backend/utils/adt/selfuncs.c

@@ -15,7 +15,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.180 2005/06/05 22:32:57 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.181 2005/06/10 22:25:36 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -4221,12 +4221,11 @@ genericcostestimate(PlannerInfo *root,
 	 * of partial redundancy (such as "x < 4" from the qual and "x < 5"
 	 * from the predicate) will be recognized and handled correctly by
 	 * clauselist_selectivity().  This assumption is somewhat fragile,
-	 * since it depends on pred_test() and clauselist_selectivity() having
-	 * similar capabilities, and there are certainly many cases where we
-	 * will end up with a too-low selectivity estimate.  This will bias
-	 * the system in favor of using partial indexes where possible, which
-	 * is not necessarily a bad thing.	But it'd be nice to do better
-	 * someday.
+	 * since it depends on predicate_implied_by() and clauselist_selectivity()
+	 * having similar capabilities, and there are certainly many cases where
+	 * we will end up with a too-low selectivity estimate.  This will bias the
+	 * system in favor of using partial indexes where possible, which is not
+	 * necessarily a bad thing. But it'd be nice to do better someday.
 	 *
 	 * Note that index->indpred and indexQuals are both in implicit-AND form,
 	 * so ANDing them together just takes merging the lists.  However,

src/include/optimizer/paths.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.84 2005/06/05 22:32:58 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.85 2005/06/10 22:25:37 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -49,7 +49,6 @@ extern bool match_index_to_operand(Node *operand, int indexcol,
 extern List *expand_indexqual_conditions(IndexOptInfo *index,
 										 List *clausegroups);
 extern void check_partial_indexes(PlannerInfo *root, RelOptInfo *rel);
-extern bool pred_test(List *predicate_list, List *restrictinfo_list);
 extern List *flatten_clausegroups_list(List *clausegroups);
 
 /*

src/include/optimizer/predtest.h

+/*-------------------------------------------------------------------------
+ *
+ * predtest.h
+ *	  prototypes for predtest.c
+ *
+ *
+ * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * $PostgreSQL: pgsql/src/include/optimizer/predtest.h,v 1.1 2005/06/10 22:25:37 tgl Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef PREDTEST_H
+#define PREDTEST_H
+
+#include "nodes/primnodes.h"
+
+
+extern bool predicate_implied_by(List *predicate_list,
+								 List *restrictinfo_list);
+
+#endif   /* PREDTEST_H */