[jjirsa]

Cassandra is very good when all of these are true:

- You're willing to give up some common SQL-isms for leaderless, multi-dc, high-availability

- You're going to grow to need more than one machine taking writes - if you can fit on one normal commodity machine, just use something designed for one machine. Cassandra sacrifices a lot to scale to ~thousand-machines-per-cluster, so if you can use one machine, don't bother with Cassandra.

- You can model your data in a way that does SELECTs without JOINs, and always uses AT LEAST the partition key in the WHERE clause. Denormalizing and duplicating your data is PROBABLY ok.

- You're willing to run Java (so you understand that you may need to tune the JVM eventually), and you're willing to learn about data modeling before you just start writing code

If all of that is true, Cassandra starts being interesting.