[emmelaich]

You can have the main key issuing server issue blocks to distributed key issuing servers. The keys are not necessarily increasing with respect to row creation time nor are they gapless but it's good enough for many purposes. It's also still a SPoF but not a single point of contention bad enough to affect performance significantly.

[jaylevitt]

Interesting.. how do you deal with ID collisions after rollover? That was our big problem, even with 8-byte IDs - the ID allocator had to know the Global Truth. Dealing with collisions as "exception, try the next one" was too expensive, though with faster hardware that may be moot.

[emmelaich]

Yes, rollover is an interesting problem. With the app and scale that we're operating at that will not happen within the next few thousand centuries though. I'm actually describing how I might go about doing it, and what I /think/ Oracle RAC does.

I'm not actually certain as to the implementation.