MongoDB Cannot create a namespace in multi-document transaction
Today in this article we shall see how to fix the MongoDB error MongoDB Cannot create a namespace in a multi-document transaction.
Today in this article, we will cover below aspects,
Issue Description
MongoDB gives errors,
MongoDB Cannot create a namespace in multi-document transaction
Resolution
While performing a multi-document operation using MongoDB Driver produces the below error.
This error could be possible using any MongoDb driver like C# MongoDB or node.js or spring boot etc.
I had below sample example where i have defined Transaction scope,
using (var session = await _mongoClient.StartSessionAsync())
{
// Begin transaction
session.StartTransaction();
//Update the Books Order collection
var update = Builders<BsonDocument>.Update.Set("OrderId", orderId);
var updateBuilder = Builders<Library>.Update;
await orderCollection.UpdateOneAsync(filter, update);
//Update Books collection for nested array
await booksCollection.UpdateOneAsync(x => x.userId == inputUserId,
Builders<Library>.Update.Set("books.$[g].config.$[c].value", inputValue),
new UpdateOptions
{
ArrayFilters = new List<ArrayFilterDefinition>
{
new BsonDocumentArrayFilterDefinition<BsonDocument>(new BsonDocument("g.book_name", inputBookName)),
new BsonDocumentArrayFilterDefinition<BsonDocument>(new BsonDocument("c.key", key))
}
});
//All good , let's commit the transaction
await session.CommitTransactionAsync();
}
- After initial trivial, I found one of the collections in was not existing in the MongoDB Database.
- After some research, I found that transaction in mongo currently doesn’t support collection creation within the scope for Mongo Driver version 4.2 and below.
- You need to make sure collections exist before you perform the MongoDB transaction.
- Please verify your collection name is also correct.
After creating the collection and performing the transaction, I was able to resolve the issue.
MongoDB 4.4 and support for collection creation
This is one of the recent features added to MongoDB. With MongoDB version 4.4 and above now support implicit creation of the collection. You can now create an index within the transaction scope.
MongoDB 4.2 and earlier version – No Support for collection creation
For MongoDB 4.2 and earlier versions, creating or dropping a collection or an index, are disallowed for the Transaction operation as they affect the database catalog.
If needed you can perform the collection creation before any transaction.
References:
Did I miss anything else in these resolution steps?
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