MongoDB version 5.X+ introduced the new Slot Based Execution (SBE) query engine. At the same time, the Classic Query Engine is available as well. This is a feature request to introduce a functionality that will allow users to "hint" and use a particular Query Engine while running a query. The benefits of this will be:
- It will provide the ability to compare/investigate the performance difference for queries while using either query engine, in real-time.
- It would make it unnecessary to "switch" the entire query engine (by enabling/disabling SBE) for all the queries, just to compare/investigate the query performance difference with the 2 engines for a small subset of queries.