public function getCustomIterator($dbSelect = null)
 {
     if ($dbSelect === null) {
         $db = Zend_Registry::get('dbAdapter');
         $handlerSelect = $db->select()->from('handlers', 'dataIntegrationDatasourceId')->where('handlerType = ?', $this->handlerType);
         $dbSelect = $db->select()->from($this->_table)->where('handlerType = ?', $this->handlerType)->where('dataIntegrationDatasourceId NOT IN ( ' . $handlerSelect->__toString() . ' )', $this->handlerType)->order('name');
     }
     return parent::getIterator($dbSelect);
 }