The basic goal of this issue is to fix the fact that if 2 different clients issue "simultaneously" the 2 following updates:
then, if both updates get the same timestamp, then currently, we don't guarantee that at the end the sum of v1 and v2 will be 0 (it won't be in that case).
The idea to solves this is to make sure 2 updates never get the same "timestamp" by making the timestamp be the sum of the current time (and we can relatively easily make sur no 2 update coordinated by the same node have the same current time) and a small ID unique to each server node. We can generate this small unique server id thanks to CAS (see
Let's note that this solution is only for server-side generated timestamps. Client provided timestamp will still be allowed, but in that case it will be the job of the client to synchronize to not generate 2 identical timestamp if they care about this behavior.
CASSANDRA-6106 for some related discussion on this issue.