Back-patch fix for erroneous selectivity of not-equals.

diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index 4718dc668a7313fb5a21d6b50c666f0360acf733..246a8d6086d23974846563ace02a9a7ac0bb16c1 100644 (file)
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -15,7 +15,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.66 2000/05/26 17:19:15 tgl Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.66.2.1 2000/09/23 21:27:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -255,9 +255,24 @@ neqsel(Oid opid,
           Datum value,
           int32 flag)
 {
+       Oid                     eqopid;
        float64         result;
 
-       result = eqsel(opid, relid, attno, value, flag);
+       /*
+        * We want 1 - eqsel() where the equality operator is the one associated
+        * with this != operator, that is, its negator.
+        */
+       eqopid = get_negator(opid);
+       if (eqopid)
+       {
+               result = eqsel(eqopid, relid, attno, value, flag);
+       }
+       else
+       {
+               /* Use default selectivity (should we raise an error instead?) */
+               result = (float64) palloc(sizeof(float64data));
+               *result = DEFAULT_EQ_SEL;
+       }
        *result = 1.0 - *result;
        return result;
 }