On Jan 5, 2011, at 8:55 AM, Bill Moran wrote:

> That statement demonstrates a lack of investigation and/or consideration
> of the circumstances.

No, it doesn't.

> However, if there are 5000 devices generating 100 UUIDs per hour, and you'll
> be keeping those records for 10+ years, the chances of collisions near
> the end of that 10 year span get high enough to actually make developers
> nervous.

No, they don't. At the end of your hypothetical 10-year period, you will have used about 43,000,000,000 UUIDs, or about 1/100,000,000,000,000,000,000,000,000th of the UUID space (assuming random UUIDs). Leaving you with a chance of a single collision of about 1/18,000,000,000,000,000.

Assuming of course good entropy. If the generation of random numbers is bad, then UUIDs are not so useful ;-)

-- 
Scott Ribe
scott_ribe(at)elevated-dev(dot)com
http://www.elevated-dev.com/
(303) 722-0567 voice

In response to

• Re: UUID column as pimrary key? at 2011-01-05 15:55:22 from Bill Moran

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• Re: UUID column as pimrary key? at 2011-01-05 19:03:24 from Bill Moran

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