public function delete()
 {
     $this->openTransaction();
     if ($this->getDataID()) {
         $conn_w = $this->establishConnection('w');
         $data_table = new PhabricatorWorkerTaskData();
         queryfx($conn_w, 'DELETE FROM %T WHERE id = %d', $data_table->getTableName(), $this->getDataID());
     }
     $result = parent::delete();
     $this->saveTransaction();
     return $result;
 }