In theory, in some cases it would be nice to select / deselect oversized events using $bsonSize function, e.g.:

{ $match: { $expr: { $lt: [{ $bsonSize: "$$ROOT" }, 16000000] } } }

Currently though, the $bsonSize function will throw BSONObjectTooLarge error when applied to a large documents in intermediate results.

It would be nice to allow $bsonSize expression on intermediate results >16MB.