Kellabyte rightfully points out that leveldb was designed primarily for mobile devices, and that there have been many things that can be done that weren’t because of that design goal. I was already pointed out to HyperDex’s port of leveldb, and I am also looking into what Basho is doing with it.
You can read a bit about what HyperDex did to improve things here. And Basho challenges are detailed in the following presentation. The interesting thing about this is why people want to go to leveldb to start with.
To put it simply, it is a really good product, in the sense that it is doing what it needs to do, and it is small enough so you can understand it in a reasonably short order. The fun starts when you disagree with the decisions made for you by leveldb, it is actually quite easy to make changes to the root behavior of the project without making significant changes to the overall architecture. Looking over the HyperDex changes overview, it appears that they were able to make very targeted changes. All the hard problems (storing, searching, atomicity, etc) were already solved, now the problem is dealing with optimizing them.
I’m going to review the changes made by both Basho & HyperDex to leveldb, because I think that it would be a facinating object of study. In particular, I was impressed with how leveldb merged transactions, and I am looking forward at how HyperDex parallelized them.