public function newQuery($class, $criteria= null, $cacheFlag= true) {
        $xpdoQueryClass= '\\xPDO\\Om\\' . $this->config['dbtype'] . '\\xPDOQuery';
        if ($query= new $xpdoQueryClass($this, $class, $criteria)) {
            $query->cacheFlag= $cacheFlag;
        }
        return $query;
    }