You're right, you haven't tried REQL =]. As a developer of a RethinkDB driver and a fairly active user of the database, and also a previous fan of Mongo, I can

You're right, you haven't tried REQL =]. As a developer of a RethinkDB driver and a fairly active user of the database, and also a previous fan of Mongo, I can tell you that REQL kicks the shit out of MongoDB's querying. SQL really is well-geared towards relational, flat database systems. Mongo's querying is an obtuse command-based language that always felt like it was adding hacks on hacks to get the data you wanted. REQL is almost like having your data in-memory, and you're running programmatic expressions on it that seamlessly melt into your native language. The lack of a query optimizer almost makes it better because you have to think about your query plans and indexes instead of just firing it off at the server and crossing your fingers. You're not running commands, you're processing data. I don't have a lot of experience scaling Rethink, but I do know from reading the docs and architecture that it scales out better than most SQL servers will and certainly scale up better than Mongo. I've tried to scale both MySQL and Mongo. Both are difficult and painful. You can't conclude that because of Mongo's failures, SQL beats Rethink. Rethink is light years ahead of Mongo.