1) is a your data relational or document. This should be the top decider if you're going to go for a relational database or a document store. Document stores ca

1) is a your data relational or document. This should be the top decider if you're going to go for a relational database or a document store. Document stores can be easy to work within the beginning, but they can also get in your way. Many companies as they grow end up with both. What is the best for you today? What's the best way to model your data. 2) once you know that, then you can start asking questions about what type of datastore to use. Don't think too hard about it at this point, once you know what you need to do, the difference between the different engines is unlikely to sway your decisions much. We started with DynamoDB, and recently ported over to MySQL (on RDS) prior to launch. DynamoDB was SO easy to get started with, but it wasn't too long before we were tripping over ourselves with things we could do very easily with an SQL database. We'll add in a document store again when we're bigger and need that functionality.