From mailing list: https://groups.google.com/a/lists.datastax.com/forum/#!topic/java-driver-user/0io6HfftEuo
This policy retries queries in only two cases:
On a read timeout, if enough replicas replied but data was not retrieved.
On a write timeout, if we timeout while writing the distributed log used by batch statements.
This does not include detail about unavailable and request error cases, we should include those.