Yeah, I guess this is why I didn't understand how they could use 64 bit numbers to begin with... I couldn't see how they were going to be able to generate them

Yeah, I guess this is why I didn't understand how they could use 64 bit numbers to begin with... I couldn't see how they were going to be able to generate them all without leaving huge gaps in the number-space. If you used 64bit ints you'd be unable to have one machine do the generating, so you'd have to have some sort of offset for the worker who generated the ID at the very least. And once you've done that, why not just go all out and use UUIDs?