public int Delete(string collection, IEnumerable <BsonValue> ids)
 {
     try
     {
         NotificationService.Cache.AddDocuments(collection, ids);
         var result = _engine.Delete(collection, ids);
         NotificationService.Notify();
         return(result);
     }
     catch (Exception ex)
     {
         throw ex;
     }
     finally
     {
         NotificationService.Clear();
     }
 }