On Thursday 06 January 2011 7:14:00 am Bill Moran wrote:
> In response to Scott Ribe <scott_ribe@elevated-dev.com>:
> > On Jan 6, 2011, at 1:52 AM, Stuart Bishop wrote:
> > > If you are looking at these extreme
> > > improbabilities, your SERIAL isn't guaranteed unique either when you
> > > take into account cosmic rays flipping the right bits in your ECC
> > > memory or on your disk platter.
> >
> > Yes, that's rather the point, the probability is so extremely low that it
> > in most cases it should be treated as 0. Some people seem to have a
> > problem wrapping their heads around relative magnitudes that extreme.
>
>
> There. I Godwined the damn thing.
>
> --
> Bill Moran
Maybe a wrap up is in order:)
As I said earlier this is one of those arguments that could go forever because
everyone is right, so to summarize:
1) UUIDs can have a very to extremely large namespace but less than infinite.
2) There are other alternatives i.e SERIAL
3) Managing the above is based on the interaction of three components -
software,hardware,wetware(people). Any one of which can have a weakness and in
combination their are many permutations.
4) DBAs need to plan for the worse. Worse being somewhat contextual. Real time
control of a nuclear plant versus Web social media. Choosing a unique number
generator and dealing with possible collisions is contingent on this context.
--
Adrian Klaver
adrian.klaver@gmail.com