What’s Coming to Cassandra in 3.0: Improved Hint Storage and Delivery

Hinted handoff (HH) is an integral part of Cassandra's write path that helps reduce inconsistency caused by temporary node unavailability periods. In earlier versions, hints were stored in a regular Cassandra table called system.hints. However, this approach had some drawbacks, including the use of queues and potential tombstone issues. To address these issues, starting with Cassandra 3.0, hints are stored in flat files, bypassing the storage engine altogether. This new implementation simplifies the replay process and reduces overall overhead surrounding hints.