protected function getNullUUIDs(\databox $databox)
    {
        $sql = 'SELECT r.coll_id, r.type, r.record_id, s.path, s.file, r.xml
                FROM record r, subdef s
                        WHERE ISNULL(uuid)
                        AND s.record_id = r.record_id AND s.name="document"
                        AND parent_record_id = 0 LIMIT 100';

        $stmt = $databox->get_connection()->prepare($sql);
        $stmt->execute();
        $rs = $stmt->fetchAll(\PDO::FETCH_ASSOC);
        $stmt->closeCursor();

        return $rs;
    }