If you are looking for something like CouchDB but only syncs partial subsets of the data you request (rather than the whole thing), try checking out https://git

If you are looking for something like CouchDB but only syncs partial subsets of the data you request (rather than the whole thing), try checking out https://github.com/amark/gun https://github.com/amark/gun (disclosure: I build it). However Postgres is probably the best database choice out there right now, so you made a good decision.