Etcd: Does etcd keep order by event occur order when send watch event?

[xiaoyulei]

I watch a key, and delete and add. etcd will send two event. Does these two event message order is same to operation order? Is it possible add message arrive first?

[xiang90]

etcd preserves the event ordering.

Does these two event message order is same to operation order?

Yes.

Is it possible add message arrive first?

No, unless there is a bug.

[inksink]

@xiang90 But how to understand :

etcd does not ensure linearizability for watch operations. Users are expected to verify the revision of watch responses to ensure correct ordering.

from https://coreos.com/etcd/docs/latest/learning/api_guarantees.html

thx.