We have a use case in which we want to read consistency data between service calls.

For example:

• Service A calls Service B.
  • Service B returns the data from MongoDB and the session timestamp.
• Service A then processes the data.
• Possible: Service C changes the data in MongoDB.
• Service A then calls Service B again, this time with the session timestamp from the first call.
  • Service B returns the data from MongoDB with the provided session timestamp, excluding changed data from Service C.

Note: We ensure that the time between the two read operations is short enough for Mongo to provide the data.

This solution was proposed by our MongoDB consultant.

Currently, we use the following code to set the snapshot time for the read operation:

session = await _mongoClient.StartSessionAsync(new ClientSessionOptions() { Snapshot = true }, cancellationToken);            session.WrappedCoreSession.SetSnapshotTimeIfNeeded(snapshotTimestamp.BsonTimestamp); 

This code uses the internals of the MongoDB driver, and there have been discussions to remove the WrappedCoreSession property.

We need an officially supported way to read snapshots with an externally provided timestamp.