Optimizer can now estimate selectivity of IS NULL, IS NOT NULL,

IS TRUE, etc, with some degree of verisimilitude.  Split out
selectivity support functions from builtins.h into a new header
file selfuncs.h, so as to reduce the number of header files builtins.h
must depend on.  Fix a few missing inclusions exposed thereby.
From Joe Conway, with some kibitzing from Tom Lane.

1 files changed, 16 insertions, 1 deletions

diff --git a/src/backend/optimizer/path/clausesel.c b/src/backend/optimizer/path/clausesel.c
index cafc01fc33..36d8f229f1 100644
--- a/src/backend/optimizer/path/clausesel.c
+++ b/src/backend/optimizer/path/clausesel.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/clausesel.c,v 1.45 2001/06/05 05:26:04 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/clausesel.c,v 1.46 2001/06/25 21:11:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -24,6 +24,7 @@
 #include "parser/parsetree.h"
 #include "utils/fmgroids.h"
 #include "utils/lsyscache.h"
+#include "utils/selfuncs.h"
 
 
 /* note that pg_type.h hardwires size of bool as 1 ... duplicate it */
@@ -509,6 +510,16 @@ clause_selectivity(Query *root,
 		 */
 		s1 = (Selectivity) 0.5;
 	}
+	else if (IsA(clause, NullTest))
+	{
+		/* Use node specific selectivity calculation function */
+		s1 = nulltestsel(root, (NullTest *) clause, varRelid);
+	}
+	else if (IsA(clause, BooleanTest))
+	{
+		/* Use node specific selectivity calculation function */
+		s1 = booltestsel(root, (BooleanTest *) clause, varRelid);
+	}
 	else if (IsA(clause, RelabelType))
 	{
 		/* Not sure this case is needed, but it can't hurt */
@@ -517,5 +528,9 @@ clause_selectivity(Query *root,
 								varRelid);
 	}
 
+#ifdef SELECTIVITY_DEBUG
+	elog(NOTICE, "clause_selectivity: s1 %f", s1);
+#endif	 /* SELECTIVITY_DEBUG */
+
 	return s1;
 }