diff -Nurb postgresql-8.1.4/src/backend/utils/adt/numutils.c postgresql-8.1.4-patched/src/backend/utils/adt/numutils.c
--- postgresql-8.1.4/src/backend/utils/adt/numutils.c	2005-12-01 00:10:16.000000000 +0100
+++ postgresql-8.1.4-patched/src/backend/utils/adt/numutils.c	2006-10-13 12:05:34.000000000 +0200
@@ -55,6 +55,9 @@
  * Unlike plain atoi(), this will throw ereport() upon bad input format or
  * overflow.
  */
+
+bool empty_equals_0;
+
 int32
 pg_atoi(char *s, int size, int c)
 {
@@ -68,6 +71,9 @@
 	if (s == NULL)
 		elog(ERROR, "NULL pointer");
 	if (*s == 0)
+		if(empty_equals_0)
+			return (int32)0;
+		else
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
 				 errmsg("invalid input syntax for integer: \"%s\"",
diff -Nurb postgresql-8.1.4/src/backend/utils/misc/guc.c postgresql-8.1.4-patched/src/backend/utils/misc/guc.c
--- postgresql-8.1.4/src/backend/utils/misc/guc.c	2006-05-21 22:11:02.000000000 +0200
+++ postgresql-8.1.4-patched/src/backend/utils/misc/guc.c	2006-10-13 12:05:57.000000000 +0200
@@ -97,6 +97,7 @@
 extern int	CommitSiblings;
 extern char *default_tablespace;
 extern bool fullPageWrites;
+extern bool empty_equals_0;

 #ifdef TRACE_SORT
 extern bool trace_sort;
@@ -395,6 +396,14 @@
 static struct config_bool ConfigureNamesBool[] =
 {
 	{
+                {"empty_equals_0", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
+                        gettext_noop("Treats the empty string as 0 when dealing with integers"),
+                        NULL
+                },
+                &empty_equals_0,
+                false, NULL, NULL
+        },
+	{
 		{"enable_seqscan", PGC_USERSET, QUERY_TUNING_METHOD,
 			gettext_noop("Enables the planner's use of sequential-scan plans."),
 			NULL