There's actually two distinct things you might want to know: 1) The current state of the system. 2) Whether the current state of the system is equal to or lat

There's actually two distinct things you might want to know: 1) The current state of the system. 2) Whether the current state of the system is equal to or later than one reflecting your change. #1 is technically unknowable without a locking mechanism, but #2 is theoretically possible. Assuming reliable time synchronization, your worst-case scenario would be a timestamp on every record, and checking the timestamp on each node (you can do this with Cassandra, for example).