HUIDs have the birthday problem. How many people do you need to have in a group before two of them will have the same birthday? HUIDs can only be called LUID's (Locally Unique Identifiers) if you go to the trouble of ensuring uniqueness *before* using one. Validating Global uniqueness is, quite obviously, a very difficult problem.
> -----Original Message----- > From: sqlite-users-bounces at mailinglists.sqlite.org [mailto:sqlite-users- > bounces at mailinglists.sqlite.org] On Behalf Of Jean-Christophe Deschamps > Sent: Wednesday, 20 May, 2015 15:38 > To: General Discussion of SQLite Database > Subject: Re: [sqlite] AUTOINC vs. UUIDs > > At 23:24 20/05/2015, you wrote: > > >On Wed, May 20, 2015 at 2:20 PM, Steven M. McNeese > ><steven.mcneese at freedomparkdfw.com> wrote: > > > Often times people will use GUIDs as primary keys when different > > systems need to generate > > > rows and then merge together. Like an application that works with > > offline clients that push the > > > data to a server when the connect. However there are other ways of > > accomplishing the same thing. > > > >For curiosity - Is there a site/blog post somewhere > >enumerating/listing these other ways ? > > I don't know, but let's say your rowids range from -9223372036854775807 > to 9223372036854775807, that's 18446744073709551614 possible rowids. > > Imagine that in 50 years, the total population on Earth will grow to > (say) 50 billion people (I hope it won't!). > > 18 446 744 073 709 551 614 / 50 000 000 000 = 368 934 881.474 191 032 28 > > That leaves you the possibility to assign a unique identifier to every > potential client on the planet (and a big one) in nearly 369 million > servers concurrently without the faintest risk of collision. > > At this rate, you may limit rowids to only positive integers ... and > hire a large army of telemarketers. > > _______________________________________________ > sqlite-users mailing list > sqlite-users at mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
