| From: | Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | meetesh(dot)karia(at)alumni(dot)duke(dot)edu, pgsql-bugs(at)postgresql(dot)org |
| Subject: | Re: UUIDs generated using ossp-uuid on windows not unique |
| Date: | 2008-06-16 20:01:57 |
| Message-ID: | 4856C6B5.2030303@kaltenbrunner.cc |
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| Lists: | pgsql-bugs |
Tom Lane wrote:
> Meetesh Karia <meetesh(dot)karia(at)gmail(dot)com> writes:
>> As best as I can tell, the problem is caused because generation of v1
>> UUIDs uses GetSystemTimeAsFileTime which is stated to have a resolution
>> of 100 nanoseconds but in practice has a resolution of around 15ms
>> (http://www.ddj.com/showArticle.jhtml?documentID=win0305a&pgno=17).
>
> Well, any real-time clock reading is going to have finite resolution.
> If your app is expecting that version-1 UUIDs generated in rapid
> succession will be distinct, I think your app is broken. It's just
> a little more obvious on Windows :-(.
>
> Perhaps the v4 generation method would work better for you?
actually this has been reported before and seems to be an issue in the
windows port of the ossp-uuid library:
http://archives.postgresql.org/pgsql-bugs/2008-05/msg00059.php
Stefan
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