diff --git a/src/backend/commands/variable.c b/src/backend/commands/variable.c
index 2c813dcd597..9cd2c5d699c 100644
--- a/src/backend/commands/variable.c
+++ b/src/backend/commands/variable.c
@@ -2,7 +2,7 @@
  * Routines for handling of 'SET var TO',
  *	'SHOW var' and 'RESET var' statements.
  *
- * $Id: variable.c,v 1.12 1998/09/01 04:28:07 momjian Exp $
+ * $Id: variable.c,v 1.13 1998/09/03 02:34:29 momjian Exp $
  *
  */
 
@@ -24,6 +24,7 @@ extern Cost _cpu_index_page_wight_;
 extern bool _use_geqo_;
 extern int32 _use_geqo_rels_;
 extern bool _use_right_sided_plans_;
+extern bool _use_keyset_query_optimizer;
 
 /*-----------------------------------------------------------------------*/
 static const char *
@@ -558,6 +559,9 @@ struct VariableParsers
 		"server_encoding", parse_server_encoding, show_server_encoding, reset_server_encoding
 	},
 #endif
+	{
+		"ksqo", parse_ksqo, show_ksqo, reset_ksqo
+	},
 	{
 		NULL, NULL, NULL, NULL
 	}
@@ -613,3 +617,47 @@ ResetPGVariable(const char *name)
 
 	return TRUE;
 }
+
+
+/*-----------------------------------------------------------------------
+KSQO code will one day be unnecessary when the optimizer makes use of 
+indexes when multiple ORs are specified in the where clause.
+See optimizer/prep/prepkeyset.c for more on this.
+	daveh@insightdist.com    6/16/98
+-----------------------------------------------------------------------*/
+bool
+parse_ksqo(const char *value)
+{
+	if (value == NULL)
+	{
+		reset_ksqo();
+		return TRUE;
+	}
+
+	if (strcasecmp(value, "on") == 0)
+		_use_keyset_query_optimizer = true;
+	else if (strcasecmp(value, "off") == 0)
+		_use_keyset_query_optimizer = false;
+	else
+		elog(ERROR, "Bad value for Key Set Query Optimizer (%s)", value);
+
+	return TRUE;
+}
+
+bool
+show_ksqo()
+{
+
+	if (_use_keyset_query_optimizer)
+		elog(NOTICE, "Key Set Query Optimizer is ON");
+	else
+		elog(NOTICE, "Key Set Query Optimizer is OFF");
+	return TRUE;
+}
+
+bool
+reset_ksqo()
+{
+	_use_keyset_query_optimizer = false;
+	return TRUE;
+}
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 7d4091c4aa0..e513b4f3680 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.32 1998/09/01 04:29:53 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.33 1998/09/03 02:34:30 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -68,6 +68,7 @@ planner(Query *parse)
 	PlannerInitPlan = NULL;
 	PlannerPlanId = 0;
 
+	transformKeySetQuery(parse);
 	result_plan = union_planner(parse);
 
 	Assert(PlannerQueryLevel == 1);
diff --git a/src/backend/optimizer/prep/Makefile b/src/backend/optimizer/prep/Makefile
index 6255a853d49..8ece58c872a 100644
--- a/src/backend/optimizer/prep/Makefile
+++ b/src/backend/optimizer/prep/Makefile
@@ -4,7 +4,7 @@
 #    Makefile for optimizer/prep
 #
 # IDENTIFICATION
-#    $Header: /cvsroot/pgsql/src/backend/optimizer/prep/Makefile,v 1.7 1998/04/06 00:23:48 momjian Exp $
+#    $Header: /cvsroot/pgsql/src/backend/optimizer/prep/Makefile,v 1.8 1998/09/03 02:34:32 momjian Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -13,7 +13,7 @@ include ../../../Makefile.global
 
 CFLAGS += -I../..
 
-OBJS = prepqual.o preptlist.o prepunion.o
+OBJS = prepqual.o preptlist.o prepunion.o prepkeyset.o
 
 # not ready yet: predmig.o xfunc.o
 
diff --git a/src/include/commands/variable.h b/src/include/commands/variable.h
index 4acb4267106..2a92f327bfb 100644
--- a/src/include/commands/variable.h
+++ b/src/include/commands/variable.h
@@ -2,7 +2,7 @@
  * Headers for handling of 'SET var TO', 'SHOW var' and 'RESET var'
  * statements
  *
- * $Id: variable.h,v 1.6 1998/09/01 04:35:40 momjian Exp $
+ * $Id: variable.h,v 1.7 1998/09/03 02:34:34 momjian Exp $
  *
  */
 #ifndef VARIABLE_H
@@ -54,5 +54,8 @@ extern bool set_geqo(void);
 extern bool show_geqo(void);
 extern bool reset_geqo(void);
 extern bool parse_geqo(const char *);
+extern bool show_ksqo(void);
+extern bool reset_ksqo(void);
+extern bool parse_ksqo(const char *);
 
 #endif	 /* VARIABLE_H */
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index b0d74cd5f70..9860af8a752 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: planmain.h,v 1.15 1998/09/01 04:37:17 momjian Exp $
+ * $Id: planmain.h,v 1.16 1998/09/03 02:34:35 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -61,5 +61,6 @@ extern void del_agg_tlist_references(List *tlist);
 extern List *check_having_qual_for_aggs(Node *clause,
 						   List *subplanTargetList, List *groupClause);
 extern List *check_having_qual_for_vars(Node *clause, List *targetlist_so_far);
+extern void transformKeySetQuery(Query *origNode);
 
 #endif	 /* PLANMAIN_H */