[tracker1]

RethinkDB is in my mind firstly Mongo done right... Cassandra is a very different beast, but seems to be the better option when you need massive (100+ node clusters) scaling, but that comes with a lot of work in terms of development.

While RethinkDB is probably most comparable to Mongo, it's worth noting that the sharding/replication/fail-over support and model is much better than Mongo's. Beyond that, the update notifications (streams) are in the box, where with mongo it's bolt-on. Also, rethink supports joins at the server (though best to avoid a lot of the time).

The admin ux is pretty awesome, and the dev team has been very cool to follow.

[bogomipz]

>"Also, rethink supports joins at the server (though best to avoid a lot of the time)."

Does RethinkDB have distributed joins then? These sort of notoriously difficult to implement well no? I see you say its best to avoid. I would curious to hear you experience with them.

[tracker1]

They are difficult, and costly, performance-wise. I wouldnt use them for a large expected result-set... maybe sub-items against a single parent.