public function update($update, $session, $sessionId)
    {

        $database = $this->database;
        if (isset($update["session_registry"])) {
            $update["session_registry"] = $database->quote($update["session_registry"]);
        }

        //now update the session;
        $database->update($session->table, $update, array("session_key" => $database->quote($sessionId)));

        return true;
    }