This is terrible advice on how to build an application. As everyone who has worked on a large enterprise type project before knows, the decisions you make at t

This is terrible advice on how to build an application. As everyone who has worked on a large enterprise type project before knows, the decisions you make at the start live on. It is very rare to completely switch major parts of your architecture especially today where the database you choose will affect your entire architecture. Cassandra like Riak is multi master which means your deployment strategy would be very different to MongoDB which is still effectively master/slave.