Hyperdex is no longer maintained [1]. While the technology is impressive, the author seems to have lost interest, and is now working on something called Consus [2].

Hyperdex's problem all along was that the author — a very talented developer from what I can tell — seems more invested in his projects from the perspective academic research (he's at Cornell) than in delivering a practical, living open source project. He tried to form a company around Hyperdex (the transactional "Warp" add-on thing was commercial) even though nobody seemed to be using it; and he was the sole developer. Unfortunately, as interesting as Consus is, history seems to be repeating itself there.

But yeah, Hyperdex seemed to have real potential at one point. It was the only NoSQL K/V store (at the time) that had transactions.

[1] https://github.com/rescrv/HyperDex/issues/233

[2] https://github.com/rescrv/Consus

> It was the only NoSQL K/V store (at the time) that had transactions.

What about FoundationDB?

Not open source, though.

Warp wasn't open source either.

Good point, but at least you could try out Hyperdex and consider whether you wanted transactions. But this is pretty moot at this point, unless someone picks up Hyperdex development again.