> However, it is guaranteed unique until the year 3040.

Can I ask where you got this snippet of information?

Specifically the ideas of "guarantee" and "year 3040".

I thought that GUIDs were effectively random numbers, created
in such a way that the _chances_ of duplication were extremely
small. But still only chance and not a guarantee.

I am guessing that the date must come about from estimating
how many computers there are generating so many GUIDs per
second that a duplication is likely by that time. (Of course
if you use GUIDs for a purely in-house database across 3 PCs
you can probably expect them to be useful for much longer. :-)

--
Geoff Worboys
Telesis Computing