Context

It appears there's a way to emulate SELECT ... FOR UPDATE in MongoDB.

After setting DatabaseFeatures.has_select_for_update = True and implementing the necessary logic in the backend's SQLCompiler, check Django's `select_for_update` test app.

The MongoDB blog and and Django's documentation for select_for_update() motivate use cases.

Potential Implementation Strategy

I'm not sure where the logic will go offhand (or if it's even feasible). In SQL, it's part of the query (see query.select_for_update in SQLCompiler.as_sql()) but it seems for MongoDB, the solution is to use db.findOneAndUpdate() rather than to add something to the pipeline.

Acceptance Criteria

Pass the `select_for_update` test app with the DatabaseFeature.has_select_for_update = True set as a flag

Pitfalls

Feasibility needs research