4 ms·
It’s not just tricky and elusive, I think it’s literally unknowable -- not a well-defined question. Like asking about the simultaneity of disconnected events in
by iainmerrick 6y ago
It’s not just tricky and elusive, I think it’s literally unknowable -- not a well-defined question. Like asking about the simultaneity of disconnected events in special relativity.
- zodiac 6y agoYou can modify the question to be well-defined and not suffer those measurement problems, eg "the total number of videos uploaded before midnight UTC on 2021-04-29"
- suprfsat 6y agoInteresting, I wonder if a distributed database could be developed to consistently answer queries phrased in this way.
- hderms 6y agoSeems like it would either need to be append only or have some kind of snapshot isolation
- mmcconnell1618 6y agoGoogle Developed Spanner which is a globally distributed database that uses atomic clocks to keep things synchronized: https://static.googleusercontent.com/media/research.google.com/en//archive/spanner-osdi2012.pdf https://static.googleusercontent.com/media/research.google.c...
- zodiac 6y agoI think the Chandy-Lamport snapshot algorithm tries to do something like this for all distributed systems (in their model, and it tries to get any consistent snapshot, not allowing you to specify the "time"); not sure if it's actually useful IRL though
- nine_k 6y agoAll these nodes are in the same light cone, so we theoretically can stop all mutation and wait for the exact final state to converge to a precise number of uploaded videos. But the question of the precise number of videos before that moment is indeed ill-defined.
- iainmerrick 6y agoYou can theoretically stop all mutation, but the users might start to complain!