I was asking about DocumentDB, not MongoDB, but maybe I missed something. From their site:

> Amazon DocumentDB implements the Apache 2.0 open source MongoDB 3.6 API by emulating the responses that a MongoDB client expects from a MongoDB server, allowing you to use your existing MongoDB drivers and tools with Amazon DocumentDB

So, is this a "managed MongoDB" or is it a NOSQL AmazonDB that just implements the same API as MongoDB? If the latter, I don't think we can assume this is the same thing as MongoDB, because the internals might be completely different.