diff --git a/src/backend/utils/adt/network.c b/src/backend/utils/adt/network.c
index 56bc534c23..0a6e10f174 100644
--- a/src/backend/utils/adt/network.c
+++ b/src/backend/utils/adt/network.c
@@ -3,7 +3,7 @@
  *	is for IP V4 CIDR notation, but prepared for V6: just
  *	add the necessary bits where the comments indicate.
  *
- *	$Header: /cvsroot/pgsql/src/backend/utils/adt/network.c,v 1.29 2001/03/22 03:59:52 momjian Exp $
+ *	$Header: /cvsroot/pgsql/src/backend/utils/adt/network.c,v 1.30 2001/06/09 22:16:18 tgl Exp $
  *
  *	Jon Postel RIP 16 Oct 1998
  */
@@ -16,6 +16,7 @@
 #include <netinet/in.h>
 #include <arpa/inet.h>
 
+#include "catalog/pg_type.h"
 #include "utils/builtins.h"
 #include "utils/inet.h"
 
@@ -564,6 +565,55 @@ network_netmask(PG_FUNCTION_ARGS)
 	PG_RETURN_INET_P(dst);
 }
 
+
+/*
+ * Convert a value of a network datatype to an approximate scalar value.
+ * This is used for estimating selectivities of inequality operators
+ * involving network types.
+ *
+ * Currently, inet/cidr values are simply converted to the IPv4 address;
+ * this will need more thought when IPv6 is supported too.  MAC addresses
+ * are converted to their numeric equivalent as well (OK since we have a
+ * double to play in).
+ */
+double
+convert_network_to_scalar(Datum value, Oid typid)
+{
+	switch (typid)
+	{
+		case INETOID:
+		case CIDROID:
+		{
+			inet	   *ip = DatumGetInetP(value);
+
+			if (ip_family(ip) == AF_INET)
+				return (double) ip_v4addr(ip);
+			else
+				/* Go for an IPV6 address here, before faulting out: */
+				elog(ERROR, "unknown address family (%d)", ip_family(ip));
+			break;
+		}
+		case MACADDROID:
+		{
+			macaddr    *mac = DatumGetMacaddrP(value);
+			double		res;
+
+			res = (mac->a << 16) | (mac->b << 8) | (mac->c);
+			res *= 256*256*256;
+			res += (mac->d << 16) | (mac->e << 8) | (mac->f);
+			return res;
+		}
+	}
+
+	/*
+	 * Can't get here unless someone tries to use scalarltsel/scalargtsel
+	 * on an operator with one network and one non-network operand.
+	 */
+	elog(ERROR, "convert_network_to_scalar: unsupported type %u", typid);
+	return 0;
+}
+
+
 /*
  *	Bitwise comparison for V4 addresses.  Add V6 implementation!
  */
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index a56ac81042..099cc37e9d 100644
--- 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 1.92 2001/06/05 05:26:04 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.93 2001/06/09 22:16:18 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1326,6 +1326,9 @@ icnlikejoinsel(PG_FUNCTION_ARGS)
  *	  scale needed by scalarltsel()/scalargtsel().
  *	  Returns "true" if successful.
  *
+ * XXX this routine is a hack: ideally we should look up the conversion
+ * subroutines in pg_type.
+ *
  * All numeric datatypes are simply converted to their equivalent
  * "double" values.  XXX what about NUMERIC values that are outside
  * the range of "double"?
@@ -1398,10 +1401,22 @@ convert_to_scalar(Datum value, Oid valuetypid, double *scaledvalue,
 		case RELTIMEOID:
 		case TINTERVALOID:
 		case TIMEOID:
+		case TIMETZOID:
 			*scaledvalue = convert_timevalue_to_scalar(value, valuetypid);
 			*scaledlobound = convert_timevalue_to_scalar(lobound, boundstypid);
 			*scaledhibound = convert_timevalue_to_scalar(hibound, boundstypid);
 			return true;
+
+		/*
+		 * Built-in network types
+		 */
+		case INETOID:
+		case CIDROID:
+		case MACADDROID:
+			*scaledvalue = convert_network_to_scalar(value, valuetypid);
+			*scaledlobound = convert_network_to_scalar(lobound, boundstypid);
+			*scaledhibound = convert_network_to_scalar(hibound, boundstypid);
+			return true;
 	}
 	/* Don't know how to convert */
 	return false;
@@ -1694,6 +1709,13 @@ convert_timevalue_to_scalar(Datum value, Oid typid)
 			}
 		case TIMEOID:
 			return DatumGetTimeADT(value);
+		case TIMETZOID:
+			{
+				TimeTzADT  *timetz = DatumGetTimeTzADTP(value);
+
+				/* use GMT-equivalent time */
+				return (double) (timetz->time + timetz->zone);
+			}
 	}
 
 	/*
diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index 53a12d67fc..109d144494 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: builtins.h,v 1.149 2001/06/07 00:09:31 momjian Exp $
+ * $Id: builtins.h,v 1.150 2001/06/09 22:16:17 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -514,6 +514,7 @@ extern Datum network_broadcast(PG_FUNCTION_ARGS);
 extern Datum network_host(PG_FUNCTION_ARGS);
 extern Datum network_show(PG_FUNCTION_ARGS);
 extern Datum network_abbrev(PG_FUNCTION_ARGS);
+extern double convert_network_to_scalar(Datum value, Oid typid);
 
 /* mac.c */
 extern Datum macaddr_in(PG_FUNCTION_ARGS);