Well... Why do you need 2PC if nothing is sacrificed? :) If you choose things like Raft (or other RSM), you can get a consistent key space to do txn over keys.

Well... Why do you need 2PC if nothing is sacrificed? :) If you choose things like Raft (or other RSM), you can get a consistent key space to do txn over keys. For a metadata store like etcd, one RSM group is OK. Performance/availability is better than something requires 2PC. For database systems, there are quite a few txns that can actually fall into one shard and can bypass 2PC. Of course, it is highly depend on the workload and use cases.