Allow numeric_fac() to be interrupted, since it can take quite a while for

large inputs.  Also cause it to error out immediately if the result will
overflow, instead of grinding through a lot of calculation first.
Per gripe from Jim Nasby.

src/backend/utils/adt/numeric.c

@@ -14,7 +14,7 @@
  * Copyright (c) 1998-2007, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/numeric.c,v 1.103 2007/06/05 21:31:06 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/numeric.c,v 1.104 2007/06/09 15:52:30 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -29,6 +29,7 @@
 #include "access/hash.h"
 #include "catalog/pg_type.h"
 #include "libpq/pqformat.h"
+#include "miscadmin.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
 #include "utils/int8.h"
@@ -1560,6 +1561,11 @@ numeric_fac(PG_FUNCTION_ARGS)
 		res = make_result(&const_one);
 		PG_RETURN_NUMERIC(res);
 	}
+	/* Fail immediately if the result would overflow */
+	if (num > 32177)
+		ereport(ERROR,
+				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
+				 errmsg("value overflows numeric format")));
 
 	init_var(&fact);
 	init_var(&result);
@@ -1568,6 +1574,9 @@ numeric_fac(PG_FUNCTION_ARGS)
 
 	for (num = num - 1; num > 1; num--)
 	{
+		/* this loop can take awhile, so allow it to be interrupted */
+		CHECK_FOR_INTERRUPTS();
+
 		int8_to_numericvar(num, &fact);
 
 		mul_var(&result, &fact, &result, 0);