protected function aggregateUsers()
    {
        $userIdFieldName = self::USER_ID_FIELD;
        $visitorIdFieldName = self::VISITOR_ID_FIELD;

        /** @var \Zend_Db_Statement $query */
        $query = $this->getLogAggregator()->queryVisitsByDimension(
            array(self::USER_ID_FIELD),
            "log_visit.$userIdFieldName IS NOT NULL AND log_visit.$userIdFieldName != ''",
            array("LOWER(HEX($visitorIdFieldName)) as $visitorIdFieldName")
        );

        if ($query === false) {
            return;
        }

        $rowsCount = 0;
        while ($row = $query->fetch()) {
            $rowsCount++;
            $this->arrays->sumMetricsVisits($row[$userIdFieldName], $row);
            $this->rememberVisitorId($row);
        }
    }