semi-immutable CQL rows

There are many use cases, where data is immutable at the domain model level. Most time-series/audit trail/logging applications fit this approach.

A relatively simple way to implement a bare-bones version of this would be to have a table-level schema option for "first writer wins", so that in the event of any conflict, the more recent version would be thrown on the floor.

Obviously, this is not failure proof in the face of inconsistent timestamps, but that is a problem to be addressed outside of Cassandra.

Optional additional features could include logging any non-identical cells discarded due to collision.