The guide doc said setup NTP for physical time, but HLC can work with ad hoc clock synchronization protocols, so if PTP will get much more performance compared to NTP?
We recommend NTP because it is already familiar for a lot of people.
However, CockroachDB itself does not interact with NTP, we just want the host clocks to be reasonably accurate.
Any method that achieves that is acceptable.
PTP is more precise, so if use PTP will gain more performance?
You should see better performance and fewer retries in the case of conflicting transactions. That’s because the clock offset dictates the window of time we need to examine for other operations on the same keys.
In the case on non-conflicting operations I don’t think it will make a difference but I really need someone else to chime in here. @tschottdorf will probably know.
In the meantime, I recommend reading our blog post which covers some of the clock considerations in CockroachDB.