CockroachDB is closer to Spanner. The globally distributed primitives that power their SQL layer which is F1.
I guess that TiDB is on layer above Cockroach.
Cockroach Dev here.
We're actively working on a SQL layer actually.
We really need to update our github readme to contain info about it. It's under active development and of course, it's inspired by F1.
Cockroach dev here.
We're actually currently implementing a SQL layer within cockroach. So it wont' be layered, it's the main method of interaction with CockroachDB.
One of TiDB authors here. Our design is more similar to Google F1, currently we're focusing on building an independent SQL layer above any transactional KV storage.
Does there exist any distributed transactional KV storage engine (open source) ?
Yes, currently TiDB works well with HBase. Coming soon.
There are alse some distribute transaction layer on HBase.Ex:https://github.com/XiaoMi/themis
So TiDB is similar to the (unfortunately) abandoned FoundationDB SQL Layer, but written in a proper language? Nice :)
Aha! You got it. And we also want to build the distributed kv part in a proper way.