How does consul KV consistency works in regards to updating the same key

Question

If given a consul KV key a/key, where there are multiple agent server instances running, what happens if:

Two requests A (set value to val-a) and B (set value to val-b) are made to the create key endpoint without making use of the parameters cas or acquire in order to update the same key a/key:

• If A and B are made in parallel can the key's value become corrupted?
• Or if A comes slightly before B can the final value still become val-a?

Answer 1

The data will not be corrupted if Consul receives two write requests at the same time. The write requests would be processed serially by the leader, so the value of a/key would become either val-a or val-b, whichever is processed last.

You can find details on how Consul writes data in Consul's Consensus Protocol documentation.