protected function get_unique_db_instance_id() {
        global $CFG;

        $strkey = $CFG->dbname . ':' . $CFG->prefix;
        $intkey = crc32($strkey);
        // Normalize between 64 bit unsigned int and 32 bit signed ints. Php could return either from crc32.
        if (PHP_INT_SIZE == 8) {
            if ($intkey > 0x7FFFFFFF) {
                $intkey -= 0x100000000;
            }
        }

        return $intkey;
    }