MongoDB Optimistic Concurrency Control With .NET

Question

Using the .NET MongoDB API (MongoDB.Driver), what is the recommended approach for implementing optimistic concurrency control? For example, is there anything analogous to SQL Server's ROWVERSION/TIMESTAMP, e.g., a property that is automatically updated whenever the document changes? Or is there a trigger mechanism? Or any other mechanism?

Answer 1

There isn't anything built-in regarding optimistic concurrency in MongoDB. You need to implement that yourself if you need it.

You can do that by adding a DateTime timestamp, reading it before performing an update and using that timestamp as the filter for update. If the timestamp was changed before you had a chance to update than the update operation won't be able to find the document.

For example:

UpdateResult updateResult;
do
{
    var document = await collection.Find(_ => _.Id == id).SingleAsync(); // Get the current document
    updateResult = await collection.UpdateOneAsync(_ => _.Id == id && _.TimeStamp == document.TimeStamp, Builders<Item>.Update...); // Update the document only if the timestamp is the same
} while (updateResult.ModifiedCount == 0); // Try until an update was successfull