Currently writing the backend for the registration module for our RDF-cataloguing system, a quick description:
Components: Cassandra, Cassandra-driver, JAX-RS (Jersey)
The setup is quite simple, we do atomic writes (one-line-per-triple) with a column for s,p,o and apply an ID, a activity status boolean (active/inactive), a prior version ID and a subsequent version ID. In this way, we can simply transition between old and new versions and export complete CBDs for each URI.
I see that it should be possible to export the data as PROV and other standards. I doubt that this will be particularly challenging…now…