|
|
|
|
|
|
by kiitos
561 days ago
|
|
|
> When multiple messages are in flight in the same 'simultaneity window', different observers may receive them in different orders and vector clocks can't determine a consistent order of those events. That's right! Vector clocks only provide partial order. But partial order is the only actual truth in any distributed system. Total order is a fiction, which only exists in the context of a specific node, based on that specific node's experience of reality (message receipt). In any non-trivial distributed system, there is no consistent (total) order of events, at least not without a consensus protocol. There are lots of ways to hack a (fake) total order, and many of those approaches are enormously successful nearly all of the time. But, still, you know. |
|
|
> Logical ordering of events in a distributed system is a solved problem. The solution is vector clocks (or something like them).
A partial order solves the problem when messages are not simultaneous and so the partial order provides a total order. That there is in fact no total ordering of simultaneous messages doesn't solve the problem that users would like to have messages arrive in a consistent order without delay. This is unsolved, because it's unsolvable, therefore vector clocks aren't the solution.