Choosing a database service - mongohq vs dynamodb
===

Currently I am gathering information what database servce we should use.
I am still very new to web development but we think we want to have a noSQL database.

We are using Java with Play! 2.

We only need a database for user registration.


Now I am already familiar with GAE ndb which is a key value store such as dynamoDB. MongoDB is a document db.
I am not sure what advantages each solution has.

I also know that dynamoDB runs on SSD's and mongoDB is inmemory.

An advantage of mongoDB would be that Java Play! already "supports" mongodb.


Now we don't expect too much database usage, but we would need to scale pretty fast if our app grows.

What alternatives do I have? What pros/cons do they have?
Considering:

- Pricing
- Scaling
- Ease of use
- Play! support?

