I used CouchDB for a project back in 2012 when all of these things were fairly new. The reason was to embed the DB on an Android device. This turned out to no

I used CouchDB for a project back in 2012 when all of these things were fairly new. The reason was to embed the DB on an Android device. This turned out to not work as well as advertised. I have no idea what's happened with Couch since, but started got pretty familiar with Mongo in the last 12 months. It's OK, but it's expensive to make it performant. As other commenters here have mentioned, the primary use case for these Object/Document storage solutions seems to be to remove knowledge of Relational DB as a requirement for developers. I think it's probably excellent for prototyping, but I wouldn't want it running a heavily used product in production.