Cassandra is essentially a key-value-store. Accessing data by key is fast, everything else is slow as molasses and something you really should avoid. So to work

Cassandra is essentially a key-value-store. Accessing data by key is fast, everything else is slow as molasses and something you really should avoid. So to work with that, you fit your data to that model. Think of it as a RDBMS where you can only do primary key lookups and you're pretty much there.