alt Hacker NewsThat’s actually not at all what TrueTime guarantees and assuming they’ve solved a physical impossibility is dangerous technically as a founding assumption for higher level tech (which thankfully Spanner does not do).
What TrueTime says is that clocks are synchronized within some delta just like NTP, but that delta is significantly smaller thanks to GPS time sync. That enables applications to have tighter bounds on waiting to see if a conflict may exist before committing which is why Spanner is fast. CockroachDB works similarly but given the logistical challenge of getting GPS receivers into data centers, they worked to achieve a smaller delta through better NTP-like timestamps and generally get fairly close performance.
https://programmingappliedai.substack.com/p/what-is-true-tim...
> Bounded Uncertainty: TrueTime provides a time interval, [earliest, latest], rather than a single timestamp. This interval represents the possible range of the current time with bounded uncertainty. The uncertainty is caused by clock drift, synchronization delays, and other factors in distributed systems.
That’s exactly what I’m saying but you simply provided more details. TrueTime guarantees clocks are well synchronized: and of course that means synchronized to a reasonable upper bound. It’s no more possible for clocks to be absolutely synchronized, than for two line segments drawn independently to have absolutely the same length.