diff --git a/src/backend/executor/execUtils.c b/src/backend/executor/execUtils.c
index c6ae2d4296..5d6473dfc6 100644
--- a/src/backend/executor/execUtils.c
+++ b/src/backend/executor/execUtils.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/execUtils.c,v 1.168 2010/01/02 16:57:41 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/execUtils.c,v 1.169 2010/01/02 17:53:56 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1167,7 +1167,9 @@ check_exclusion_constraint(Relation heap, Relation index, IndexInfo *indexInfo,
 	int				i;
 	bool			conflict;
 	bool			found_self;
+	ExprContext	   *econtext;
 	TupleTableSlot *existing_slot;
+	TupleTableSlot *save_scantuple;
 
 	/*
 	 * If any of the input values are NULL, the constraint check is assumed
@@ -1194,9 +1196,19 @@ check_exclusion_constraint(Relation heap, Relation index, IndexInfo *indexInfo,
 					values[i]);
 	}
 
-	/* Need a TupleTableSlot to put existing tuples in */
+	/*
+	 * Need a TupleTableSlot to put existing tuples in.
+	 *
+	 * To use FormIndexDatum, we have to make the econtext's scantuple point
+	 * to this slot.  Be sure to save and restore caller's value for
+	 * scantuple.
+	 */
 	existing_slot = MakeSingleTupleTableSlot(RelationGetDescr(heap));
 
+	econtext = GetPerTupleExprContext(estate);
+	save_scantuple = econtext->ecxt_scantuple;
+	econtext->ecxt_scantuple = existing_slot;
+
 	/*
 	 * May have to restart scan from this point if a potential
 	 * conflict is found.
@@ -1311,6 +1323,8 @@ retry:
 						RelationGetRelationName(index)),
 				 errhint("This may be because of a non-immutable index expression.")));
 
+	econtext->ecxt_scantuple = save_scantuple;
+
 	ExecDropSingleTupleTableSlot(existing_slot);
 
 	return !conflict;
diff --git a/src/test/regress/input/constraints.source b/src/test/regress/input/constraints.source
index ee396f3703..0d278212c0 100644
--- a/src/test/regress/input/constraints.source
+++ b/src/test/regress/input/constraints.source
@@ -376,26 +376,26 @@ CREATE TABLE circles (
   c1 CIRCLE,
   c2 TEXT,
   EXCLUDE USING gist
-    (c1 WITH &&, (c2::circle) WITH ~=)
+    (c1 WITH &&, (c2::circle) WITH &&)
     WHERE (circle_center(c1) <> '(0,0)')
 );
 
 -- these should succeed because they don't match the index predicate
 INSERT INTO circles VALUES('<(0,0), 5>', '<(0,0), 5>');
-INSERT INTO circles VALUES('<(0,0), 5>', '<(0,0), 5>');
+INSERT INTO circles VALUES('<(0,0), 5>', '<(0,0), 4>');
 
 -- succeed
 INSERT INTO circles VALUES('<(10,10), 10>', '<(0,0), 5>');
 -- fail, overlaps
-INSERT INTO circles VALUES('<(20,20), 10>', '<(0,0), 5>');
+INSERT INTO circles VALUES('<(20,20), 10>', '<(0,0), 4>');
 -- succeed because c1 doesn't overlap
 INSERT INTO circles VALUES('<(20,20), 1>', '<(0,0), 5>');
--- succeed because c2 is not the same
-INSERT INTO circles VALUES('<(20,20), 10>', '<(1,1), 5>');
+-- succeed because c2 doesn't overlap
+INSERT INTO circles VALUES('<(20,20), 10>', '<(10,10), 5>');
 
 -- should fail on existing data without the WHERE clause
 ALTER TABLE circles ADD EXCLUDE USING gist
-  (c1 WITH &&, (c2::circle) WITH ~=);
+  (c1 WITH &&, (c2::circle) WITH &&);
 
 DROP TABLE circles;
 
diff --git a/src/test/regress/output/constraints.source b/src/test/regress/output/constraints.source
index 684394fd83..0800365c26 100644
--- a/src/test/regress/output/constraints.source
+++ b/src/test/regress/output/constraints.source
@@ -520,29 +520,29 @@ CREATE TABLE circles (
   c1 CIRCLE,
   c2 TEXT,
   EXCLUDE USING gist
-    (c1 WITH &&, (c2::circle) WITH ~=)
+    (c1 WITH &&, (c2::circle) WITH &&)
     WHERE (circle_center(c1) <> '(0,0)')
 );
 NOTICE:  CREATE TABLE / EXCLUDE will create implicit index "circles_c1_c2_exclusion" for table "circles"
 -- these should succeed because they don't match the index predicate
 INSERT INTO circles VALUES('<(0,0), 5>', '<(0,0), 5>');
-INSERT INTO circles VALUES('<(0,0), 5>', '<(0,0), 5>');
+INSERT INTO circles VALUES('<(0,0), 5>', '<(0,0), 4>');
 -- succeed
 INSERT INTO circles VALUES('<(10,10), 10>', '<(0,0), 5>');
 -- fail, overlaps
-INSERT INTO circles VALUES('<(20,20), 10>', '<(0,0), 5>');
+INSERT INTO circles VALUES('<(20,20), 10>', '<(0,0), 4>');
 ERROR:  conflicting key value violates exclusion constraint "circles_c1_c2_exclusion"
-DETAIL:  Key (c1, (c2::circle))=(<(20,20),10>, <(0,0),5>) conflicts with existing key (c1, (c2::circle))=(<(10,10),10>, <(0,0),5>).
+DETAIL:  Key (c1, (c2::circle))=(<(20,20),10>, <(0,0),4>) conflicts with existing key (c1, (c2::circle))=(<(10,10),10>, <(0,0),5>).
 -- succeed because c1 doesn't overlap
 INSERT INTO circles VALUES('<(20,20), 1>', '<(0,0), 5>');
--- succeed because c2 is not the same
-INSERT INTO circles VALUES('<(20,20), 10>', '<(1,1), 5>');
+-- succeed because c2 doesn't overlap
+INSERT INTO circles VALUES('<(20,20), 10>', '<(10,10), 5>');
 -- should fail on existing data without the WHERE clause
 ALTER TABLE circles ADD EXCLUDE USING gist
-  (c1 WITH &&, (c2::circle) WITH ~=);
+  (c1 WITH &&, (c2::circle) WITH &&);
 NOTICE:  ALTER TABLE / ADD EXCLUDE will create implicit index "circles_c1_c2_exclusion1" for table "circles"
 ERROR:  could not create exclusion constraint "circles_c1_c2_exclusion1"
-DETAIL:  Key (c1, (c2::circle))=(<(0,0),5>, <(0,0),5>) conflicts with key (c1, (c2::circle))=(<(0,0),5>, <(0,0),5>).
+DETAIL:  Key (c1, (c2::circle))=(<(0,0),5>, <(0,0),5>) conflicts with key (c1, (c2::circle))=(<(0,0),5>, <(0,0),4>).
 DROP TABLE circles;
 -- Check deferred exclusion constraint
 CREATE TABLE deferred_excl (