Yeah, I think MongoDB went through a set of steps
- atomically consistent at document level (which is fine for many apps as you have most related data in the single document anyways)
- atomically consistent within a collection
- and now, with MongoDB 4.0 and higher (released in 2017? 2018? whatever, a long time ago), MongoDB supports full transactional consistency across documents, collections, and shards.
It took them awhile, but they got there.
