From David’s notes on Jonathan Ellis’ Cassandra by example presentation at Devoxx:
When designing a relational schema we tend to think of objects and relationships. With Cassandra we need to think of objects and the queries we want to run against them. For each type of query you will need a column family (something like a table).
Remember the role of data modeling with NoSQL databases?
Original title and link: Notes from Cassandra by Example at Devoxx (NoSQL databases © myNoSQL)