Comment by n_u

Regarding cross-shard consistency, there's a doc here[1] on the options. In short you can just send the writes to all replicas, you can disallow cross-replica transactions (read and write), use two-phase commit to perform a distributed transaction or use their own hybrid approach that they set as the default.

[1] https://vitess.io/docs/20.0/user-guides/configuration-advanc...