MongoDB Transaction Performance

The article debunks the misconception that MongoDB transactions are inherently slow, explaining that perceived slowness typically stems from write contention under optimistic concurrency control rather than transaction overhead itself. It details how single-document operations are already transactional at the storage engine level, while multi-document transactions add snapshot isolation and atomicity across documents/collections. A benchmark inserting one million documents on a free MongoDB Atlas cluster compares single insertMany versus a session-based transaction to illustrate the actual performance characteristics.