 <p>I suggest you to get more information about Data modeling in Cassandra. I've read <a href="http://www.cs.wayne.edu/andrey/papers/TR-BIGDATA-05-2015-CKL.pdf" rel="nofollow">A Big Data Modeling Methodology for Apache Cassandra</a> and <a href="http://www.datastax.com/dev/blog/basic-rules-of-cassandra-data-modeling" rel="nofollow">Basic Rules of Cassandra Data Modeling</a> as useful articles in this case. They will help you understanding about modelling the tables based on your queries (Query-Driven methodology) and data duplication and its advantages/disadvantages. </p>