function ruleDef($table, $rule)
    {
        $q = <<<END
SELECT definition FROM pg_rules
\tWHERE schemaname = %s
\t  AND tablename = %s
\t  AND rulename = %s
END;
        $r = $this->db->query(sprintf($q, $this->db->addQuotes($this->db->getCoreSchema()), $this->db->addQuotes($table), $this->db->addQuotes($rule)));
        $row = $this->db->fetchRow($r);
        if (!$row) {
            return null;
        }
        $d = $row[0];
        return $d;
    }