[petermattis]

(Cockroach Labs co-founder here)

CockroachDB also stores SQL metadata inside of the KV store, but that metadata is also gossiped around the cluster (i.e. it is replicated to every node) so that SQL execution almost never has to read it from the KV store. Handling changes to this SQL metadata is challenging and required a design [1] that is unable to take advantage of the easy correctness of simply doing reads from the KV store on every operation.

[1] https://github.com/cockroachdb/cockroach/blob/master/docs/RF...

[elvinyung]

I see -- so how is performance? I see that there are no published numbers for e.g. TPC-C or YCSB.

(For the record -- in case I seem to be especially pessimistic -- I'm actually extremely hopeful that CRDB will actually make scaling OLTP applications significantly easier for everyone. It's just that this probably shouldn't be FDB all over again.)

[petermattis]

Performance is "ok". CockroachDB 1.0 won't be winning benchmarks, but that was never the goal. We have seen near linear scaling from 3-64 nodes on a uniformly random write workload. And the new distributed SQL execution engine has shown O(num-nodes-in-cluster) speedup on some queries. But none of this has been wrapped up into published numbers, so take it with a grain of salt.