title: aggregation operation in cloud bigtable
body: <p>I was going through BT documentation. Learned that data is stored in a column for a column family and accessed via row key. I want to understand if aggregation(such as count, sum) can be done by BT?
  As Cassandra or Scylla DB share a similar data model and provides the aggregation functionality. So heavy lifting is done at the Db side rather than application.</p>