title: How to manage duplicated Data between different tables in Query-Driven Data Model in Cassandra?
body: <p>I'm new in Cassandra NOSQL DB. I've read <a href="http://www.cs.wayne.edu/andrey/papers/TR-BIGDATA-05-2015-CKL.pdf" rel="nofollow noreferrer">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 noreferrer">Basic Rules of Cassandra Data Modeling</a> as useful articles about data modelling in Cassandra. In this pages, it's mentioned that, data duplication is used to achieve best performance (more write) based on Query-Driven methodology.OK! We will have a physical diagram as this:<br>
  <a href="https://i.stack.imgur.com/plmZc.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/plmZc.jpg" alt="enter image description here"></a><br>
  As you see, ave-rating is duplicated in three tables.The question is that, when we want to update or insert ave-rating:</p>
  
  <ul>
  <li>Does Cassandra have any tools itself to manage write in any tables having this column?(CRUD operations in duplicated Data toward some columns)</li>
  <li>Is there any third-party tool for issue, above?  </li>
  <li>Should this issue be handled in application level? if yes, what is the best practice, then?  </li>
  </ul>