public function dbSize($idServer = null)
    {
        if (is_null($idServer)) {
            $servers = $this->getServerConfig();

            $dbsize = array();
            foreach (array_keys($servers) as $idServer) {
                $redis = $this->getRedisFromServerConfig($idServer);

                $dbsize[$idServer] = $redis->dbsize();
            }
        } else {
            $redis = $this->getRedisFromServerConfig($idServer);

            $dbsize = $redis->dbsize();
        }

        return $dbsize;
    }