> "This guarantees chronological ordering, since the ServerValue.TIMESTAMP will be resolved on the Firebase server to be an accurate timestamp."
To be sure, this can't possibly guarantee chronological ordering. But it can get you fairly close and perhaps almost predictable chronological ordering...
If at any level there is a clock which can skew and is being adjusted with a stochastic process, there is jitter, and you can get out of order. The solution is simply to apply corrective factors in a continuous manor -- slow down or speed up time. That's what the client adjustment should have been doing all along, and then you would never need the ServerValue.TIMESTAMP hack.
If Firebase is relying on a ntp utility, I'm not sure but I would assume that they are smart enough to slow or speedup time and not jerk to a new setting. Or at least they would have a flag to enable that functionality.
Edit: Distributed auto-incrementing counter is not that hard. A field for time, a field for ID. I don't see a reason to conflate the two. I guess it makes object instantiating easier, since you don't have to fetch an ID in any sense. 64 vs 128 bits is not a big difference. So in the end it's a good design decision and is a net positive for them.
Seems way easier than synchronizing a clock in the browser and one on the server, and you don't have to try to account for network latency between browser and server.
> If at any level there is a clock which can skew and is being adjusted with a stochastic process, there is jitter, and you can get out of order
My understanding is that Linux has support for a monotonic clock. As long as its a single box resolving the times this shouldn't be a hard problem.
Could you please elaborate on time speed up or slow down? Or if you could refer me to some reading material? It's an interesting problem and I'd love to deep dive into it.
To be sure, this can't possibly guarantee chronological ordering. But it can get you fairly close and perhaps almost predictable chronological ordering...
If at any level there is a clock which can skew and is being adjusted with a stochastic process, there is jitter, and you can get out of order. The solution is simply to apply corrective factors in a continuous manor -- slow down or speed up time. That's what the client adjustment should have been doing all along, and then you would never need the ServerValue.TIMESTAMP hack.
If Firebase is relying on a ntp utility, I'm not sure but I would assume that they are smart enough to slow or speedup time and not jerk to a new setting. Or at least they would have a flag to enable that functionality.
Edit: Distributed auto-incrementing counter is not that hard. A field for time, a field for ID. I don't see a reason to conflate the two. I guess it makes object instantiating easier, since you don't have to fetch an ID in any sense. 64 vs 128 bits is not a big difference. So in the end it's a good design decision and is a net positive for them.