In my case, at least, PouchDB is still a lot handier of an offline-first mobile-capable DB than just about anything else, and because it speaks the CouchDB replication/sync API that still leaves a lot of use cases where CouchDB is more feasible. (It would be great to have more document DBs converge on a replication/sync API for offline-first applications. I've voted on the UserVoice suggestions to CosmosDB on the idea.)
I'm thinking about the use case to have a native app be able to work nicely with no internet connection, but then once the internet connection resumes, it downloads new data from the server and sends its offline-modified data up to the server.
From a quick search online [0] [1], I see people doing offline MongoDB sync using SQLite, but nothing like using Mongo directly. With CouchDB, we can use either the old Couchbase native app SDK, or the Cloudant native app SDK, to sync up nicely with a CouchDB instance in the cloud. We've had this running for awhile, and it works quite well, and we do not have to shuffle information to and from a SQLite database... at least, we're not doing it, since the Cloudant or Couchbase SDKs for iOS and Android keep track of all the data and store it on the mobile device however they'd like.
If there is anything similar for Mongo, I'd be interested to know!
Dunno if this thread is too cold for you to notice my reply, but there absolutely is... MongoDB Mobile was released last year, and along with Stitch, MognoDB’s serverless application platform, you can get exactly what you want — mobile sync.
CouchDB "replication" was designed to be "master-master" (or "no master" sort of) where replication is not a coordinated process but a distributed push/pull of concurrent revisions with basic conflict resolution rules.
Whereas, Mongo only built support for classic RDMS-style replication where one database serves as the master or primary, and any number of secondaries can try to keep up with it.
It's a bit like SVN versus git. Mongo when replicated still has the SVN centralized mentality, whereas CouchDB is a lot more like git.
