title: Cassandra triggers for updating a table when another is updated
body: <p>I was going through the triggers implementation in cassandra.
  I wanted to implement triggers so as to update a table with old values of the tables that has been modified.
  suppose i have a table say test_table in keyspace keyspace1.
  i also have a table say table_track in the same keyspace with columns columnname and columnvalue.
  now when a row is updated in test_table, i would like to populate the track_table with row data(in test_table before update query was executed)  in to the columns columnname and columnvalue respectively.</p>
  
  <p>i couldn't find any proper documentation regarding cassandra triggers anywhere.
  i managed to somehow implement InvertedIndex and some minor examples</p>
  
  <pre><code>public Collection&lt;Mutation&gt; augment(ByteBuffer key, ColumnFamily update)
  {
      List&lt;Mutation&gt; mutations = new ArrayList&lt;Mutation&gt;(update.getColumnCount());
  
      for (Cell cell : update)
      {
          // Skip the row marker and other empty values, since they lead to an empty key.
          if (cell.value().remaining() &gt; 0)
          {
              Mutation mutation = new Mutation(properties.getProperty("keyspace"), cell.value());
              mutation.add(properties.getProperty("columnfamily"), cell.name(), key, System.currentTimeMillis());
              mutations.add(mutation);
          }
      }
  
      return mutations;
  }
  </code></pre>
  
  <p>how can i modify the augment method to implement the functionality.
  Tnx</p>