public function count($useMasterKey = false)
    {
        $this->limit = 0;
        $this->count = 1;
        $queryString = $this->buildQueryString($this->_getOptions());
        $result = AVClient::_request('GET', '/classes/' . $this->className . '?' . $queryString, null, null,
            $useMasterKey);

        return $result['count'];
    }