title: How to implement difference aggregations / rollups on time series data in Cassandra
body: <p>I have a situation where I will be collect many time series metrics (electricity used, hours used, hours idle) from operating equipment in a manufacturing plan.  I need to create many different rollup numbers on individual and grouped assets.  For example, I need to create min, max, average electricity used over 1,5,10,30 days for a given machine.  Create same types of metrics for different groups of machines.... Many of the calculated values are driven from the raw values retrieved from the assets.  </p>
  
  <p>What is the best approach for calculating these values within a Cassandra environment?  </p>
  
  <ol>
  <li>Do I need to create 'batch jobs' that execute the calculations?</li>
  <li>It seems as if there are some built in data types (counter) in Cassandra, but seem to be some issues (simply reading some comments on stack overflow)</li>
  <li>Has anyone integrate Cassandra with a Twitter storm or something  to constantly update the counters?</li>
  </ol>
  
  <p>Thanks</p>