Re: [DOCS] uuid type not documented

Neil Conway <neilc@samurai.com> writes:
> On Tue, 2007-04-10 at 18:28 +0200, Peter Eisentraut wrote:
>> The problem is that most of the standard methods are platform dependent, as 
>> they require MAC addresses or a "good" random source, for instance.

> http://archives.postgresql.org/pgsql-patches/2007-01/msg00392.php

> ISTM random() or similar sources is a sufficient PSRNG for the purposes
> of UUID generation -- I can't see anything in the RFC that would
> contradict that.

Doesn't seem like quite enough bits of uniqueness.

We could improve matters by incorporating the database's
pg_control.system_identifier into the UUID, substituting for the MAC
address we don't have a good way to get.  system_identifier is currently
determined by the system clock at initdb time (to gettimeofday
precision), so it would add at least some additional bits of
randomness...
        regards, tom lane