If ?retrywrites=true, DeleteManyAsync() returns a MongoWriteException

Working with Data Drivers
,
1

using MongoDB C# Driver, and trying to use DeleteManyAsync() with retryable writes, so I configured it, and included ?retrywrites=true in the connection string.

Tried using DeleteManyAsync() and getting this error

```A write operation resulted in an error. WriteError: { Category : “Uncategorized”, Code : 72, Message : “Cannot use (or request) retryable writes with limit=0” }.`

So I set ?retrywrites=false, and ``DeleteManyAsync()` started working.

I saw in the documentation for retryable writes that DeleteMany isn’t supported, only single document operations are - but I would expect DeleteManyAsync to just not retry and go through, instead of erroring when used. Any ideas?

2

The backend storage is Azure Cosmos DB for MongoDB, so maybe it could be either a Cosmos DB or a MongoDB C# driver bug/issue, I’m not too sure.

3

Hi @Armies_Wagons,

Welcome to the MongoDB Community Forums! That does not sound right. Both deleteMany and deleteManyAsync still go through even if retryWrites=true is set. This does not look like a MongoDB issue. Hope that helps.

Thanks,

Rishit.

4

Hi @Rishit_Bhatia
I am using deleteMany() in the code with retrywrites=false . I get the below
Exception Message: ‘A write operation resulted in an error. WriteError: { Category : “Uncategorized”, Code : 72, Message : “Cannot use (or request) retryable writes with limit=0” }.’

5

@Maithili_Kalkar the error you described does appear to come from the MongoDB server (mongo/src/mongo/db/ops/write_ops_exec.cpp at 00da7f442804d6118cc4bbc57caf9862e9811e2b · mongodb/mongo · GitHub), so it’s possible there may be an issue here.

Do you have a self-contained reproduction you could share that shows this failure in action?

6

Hi @alexbevi
I am using deleteMany to delete the documents present. I am not sure what do you exactly need.
Here is the line of code - collection.DeleteMany(filter_id);

7

@Maithili_Kalkar can you just confirm the version of the C# driver you’re using as well as the version of MongoDB you’re connecting to?

Also how is filter_id defined?

8

@alexbevi The C# driver is 2.23.1 and MongoDb Verison is MongoDB 3.6.0 Community

filter_id its a bson document containing key and value of document to be deleted

9

Hi @Maithili_Kalkar ,

Unfortunately, I’m not able to reproduce this error. I’m using MongoDB Community 3.6.0 with the C# driver 2.23.1 as you mentioned. The retryWrites option is set in my connection string as follows:

private string connectionString = "mongodb://localhost:27017/retryWrites=false";

The query used to perform the deleteManyAsync operation looks like this:

  var filter = Builders<Restaurant>.Filter.Eq(r => r.Cuisine, "Brazilian");
  var result = await _restaurantsCollection.Find(filter).ToListAsync();
  Console.WriteLine("Trying to Delete " + result.Count + " Restaurants");
  return await _restaurantsCollection.DeleteManyAsync(filter);

Not sure if that helps but if there’s any more information you can share or a sample zip file containing sample code to reproduce this, we’d be happy to take a look at it.

Thanks,

Rishit.

10

@Rishit_Bhatia @alexbevi

I found the issue for me, it was a cosmosdb thing. You can only use DeleteMany with retryable writes enabled, as long as the filter has the partition key.

I think the error message from MongoDb driver is a little misleading then, or at least, not clear what the issue is.

11

@Maithili_Kalkar I can only tag 2 people per post for the last post. see if my comment applies to you.

12

Thanks for confirming @Armies_Wagons.

Since the MongoDB driver wasn’t designed with CosmosDB in mind the failure conditions within that environment would be unpredictable, and may surface in (potentially confusing) ways such as this.

1 Like