I am curious about the benefits and drawbacks of using a tailable cursor versus a change stream with filter for insert operations over a capped collection both in usability and performance-wise.
I have a capped collection that contains update objects. The only possible operation for this collection is insertion of new updates(as new records) which I need to relay to my application backend and distribute through SSE/WebSockets in real-time. I'll use a single parameter in the query for subscription and it is a timestamp which is part of the object's properties. The collection has an index on that field. I'll also do some basic filtering over the newly added records, so the aggregation framework of Change Streams would be helpful.
I've read: What is the difference between a changeStream and tailable cursor in MongoDB which summarizes the differences between tailable cursors and change streams in general.
Also, the mongodb article on Capped Collections just states the Tailable cursor approach and the article on Tailable cursors state that they do not use indexes and you should use a normal cursor to fetch the results.
In short, I need a reliable stream of collection updates based entirely on the insertion of new records in the collection. Which approach should I go for?
Tailable cursors and capped collections were created to support copying the oplog from a primary node to a secondary node. For any other activity the recommended approach is a ChangeStream. Change streams are integrated with the MongoDB authentication model and a change stream can be take at the collection, database, cluster and sharded cluster level. Tailable cursors only work on a single collection and are not resumable. Change streams are supported by all official MongoDB Drivers.