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From Tatu Saloranta <tsalora...@gmail.com>
Subject Re: UUIDs whose alphanumeric order is the same as their chronological order
Date Tue, 22 Jun 2010 16:04:09 GMT
On Tue, Jun 22, 2010 at 5:58 AM, David Boxenhorn <david@lookin2.com> wrote:
> I want to use UUIDs whose alphanumeric order is the same as their
> chronological order. So I'm generating Version 4 UUIDs (
...
> Is there anything wrong with this idea?

If you want to keep it completely ordered, it's probably not enough to
rely on System.currentTimeMillis(). It seems likely that it would
sometimes be called twice for same clock value?  This is easy to solve
locally (just use an additional counter, that's what UUID packages do
to get to 100 nanosecond resolution); and it might not matter in
concurrent case (intra-node ordering is arbitrary but close enough).
The other theoretical problem is reduction in random value space, but
75 bits of randomness may be well is enough.

-+ Tatu +-

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