Re: GUID's and uniqueness

Louis Frolio wrote:

> Greetings All, I have read many upon many articles here regarding GUID
> data types and uniqueness. There have been many opinions regarding
> the effectiveness of GUID's and when they should/should not be used.
> However, every article strongly implies, if it does not state it
> outright, that GUID's are always unique. My question is this, what
> happens if you have a database that uses GUID's and the NIC is changed
> out on the box? From what I understand the MAC address of the NIC is
> used as part of the algorithm to generate a GUID. If you change out
> the NIC after generating 1 billion GUID's do you run the chance of
> generating a duplicate GUID?
>
> I look forward to your insightfulness on this issue.
>
> Regards, Louis.

GUIDs are not unique except in very specific controlled situations. They are highly likely to be unique ... but there are not guarantees. And I have personally seen problems where they weren't.

-- 
Daniel A. Morgan
University of Washington
damorgan_at_x.washington.edu
(replace 'x' with 'u' to respond)