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From:Christian Parpart Date:September 21 2005 7:42pm
Subject:Re: UUIDs - first usage for me
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On Saturday 17 September 2005 21:40, Dan Nelson wrote:
> In the last episode (Sep 17), Christian Parpart said:
> > On Saturday 17 September 2005 08:34, Gleb Paharenko wrote:
> > > mysql> show create table ui\G;
> > >
> > > Table: ui
> > > Create Table: CREATE TABLE `ui` (
> > > `uuid()` varchar(36) NOT NULL default ''
> >
> > I've been testing your example as I feel really much safer with UUIDs
> > instead of auto_increments, however, my column datatype is
> > VARCHAR(12) so 24bytes shorter than a usual UUID, although, all
> > uuid() SELECTs differ only in first 12 bytes - why?
>
> The node-based uuid format that mysql generates has this format:
>
> time_low "-" time_mid "-" time_high_and_version "-"
> clock_seq_and_reserved clock_seq_low "-" node
>
> Node should be contant as long as you don't switch network cards in the
> machine, clock_seq is usually only reset across reboots (or mysql
> restarts since mysql currently generates its own uuid even if the OS
> provides a uuid generator), and time is a timestamp accurate to 100
> nanoseconds.  So assuming a single mysql server that doesn't get
> rebooted, you'll only ever see different values in the first three
> hyphenated fields.
>
> See RFC 4122 for more details.  http://www.ossp.org/pkg/lib/uuid/ is a
> nice uuid library that includes a uuid decoder.

Heya, thanks. didn't know that this is even an RFC :)

Thanks for the description.

Regards,
Christian Parpart.

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Thread
UUIDs - first usage for mesean c peters16 Sep
  • Re: UUIDs - first usage for meGleb Paharenko17 Sep
    • Re: UUIDs - first usage for meChristian Parpart17 Sep
      • Re: UUIDs - first usage for meGleb Paharenko17 Sep
      • Re: UUIDs - first usage for meDan Nelson17 Sep
        • Re: UUIDs - first usage for meChristian Parpart21 Sep