In response to Scott Ribe <scott_r...@elevated-dev.com>: > On Jan 5, 2011, at 8:05 AM, Bill Moran wrote: > > > Beyond that, the namespace size for a UUID is so incomprehensibly huge > > that the chance of two randomly generated UUIDs having the same value > > is incomprehensibly unlikely > > Yes, as in: it is *far* more likely that all of your team members and all of > your client contacts will be simultaneously struck by lightning and killed in > their sleep, and it is *far* more likely that all life on earth will be wiped > out by an asteroid impact, and it is *far* more likely that the solar system > orbits are not actually stable and earth will fly off into space... If you're > worried about UUID collisions, then either your priorities are completely > wrong, or you live in a bomb shelter--that's not sarcasm by the way, it's > simply true, the chance of a collision is so vanishingly small that it is > dwarfed by all sorts of risks that we all ignore because the chances are so > low, including the chance that all drives in all your RAIDs across all your > replicas will simultaneously fail on the same day that fires start in all the > locations where your tapes are stored and all the sprinkler systems fail... > (By "far" more likely, I mean many many many orders of magnitude...)
That statement demonstrates a lack of investigation and/or consideration of the circumstances. I can't find my math or I'd reproduce it here, but consider this: If you have 50 devices, each generating 100 UUIDs per hour, and you'll keep records for 1 year, then your argument above is probably accurate. However, if there are 5000 devices generating 100 UUIDs per hour, and you'll be keeping those records for 10+ years, the chances of collisions near the end of that 10 year span get high enough to actually make developers nervous. -- Bill Moran http://www.potentialtech.com http://people.collaborativefusion.com/~wmoran/ -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
