protected function getMetaColumns($sPrefix = '', $aCols = [])
    {
        if ($this->aMetaColumns === null) {

            $oDb                = Factory::service('Database');
            $aResult            = $oDb->query('DESCRIBE `' . $this->tableMeta . '`')->result();
            $this->aMetaColumns = [];

            foreach ($aResult as $oResult) {
                if ($oResult->Field !== 'user_id') {
                    $this->aMetaColumns[] = $oResult->Field;
                }
            }
        }

        $aCols = array_merge($aCols, $this->aMetaColumns);

        return $this->prepareDbColumns($sPrefix, $aCols);
    }