Well I don't have any code ready yet but between falling asleep today i did a little more work on a versioned data-store i've been working on ... for years, a couple of decades infact.
In it's current iteration it utilises just 3 core (simple) relational(-like) tables and can support both SVN style branches (lightweight renames) and CVS style branches (even lighter weight). Like SVN it uses global revisions and transactions but like CVS it works on a version tree rather than a path tree, but both approaches are possible within the same small library.
Together with dez it allows for compact reverse delta storage.
Originally I started in C but i've been working Java since - but i'm looking at back-porting the latest design to C again for some performance comparisons. It's always used Berkeley DB (JE for Java) as storage although I did experiment with using a SQL version in the past.
My renewed interest is that the goal is eventually run this site with it as a backing storage - for code, documentation, musings. e.g. the ability to branch a document tree for versioning and yet have it served live from common storage. This was essentially the reason I started investigating the project many years ago but never quite got there. I'm pretty sure I've got a solid schema but still need to solidify the API around a few basic use-cases before I move forward.
The last time I touched the code as 2 years ago, and the last time I did any significant code on it was 3 years ago, so it's definitely a slow burner project!
Well, more when I have more to say.