uuid type not documented

On Tue, 2007-04-10 at 17:24 +0200, Peter Eisentraut wrote:

The new uuid type is lacking documentation.

We had also talked about including some UUID generation functionality in
8.3, but it should be okay to leave that for 8.4.

-Neil

Am Dienstag, 10. April 2007 17:30 schrieb Neil Conway:

On Tue, 2007-04-10 at 17:24 +0200, Peter Eisentraut wrote:

The new uuid type is lacking documentation.

We had also talked about including some UUID generation functionality in
8.3, but it should be okay to leave that for 8.4.

The problem is that most of the standard methods are platform dependent, as
they require MAC addresses or a "good" random source, for instance. I'm not
sure how we wanted to solve that, but certainly leaving the uuid type with
*no* method to generate one is pretty poor.

--
Peter Eisentraut
http://developer.postgresql.org/~petere/

Peter Eisentraut wrote:

Am Dienstag, 10. April 2007 17:30 schrieb Neil Conway:

On Tue, 2007-04-10 at 17:24 +0200, Peter Eisentraut wrote:

The new uuid type is lacking documentation.

We had also talked about including some UUID generation functionality in
8.3, but it should be okay to leave that for 8.4.

The problem is that most of the standard methods are platform dependent, as
they require MAC addresses or a "good" random source, for instance. I'm not
sure how we wanted to solve that, but certainly leaving the uuid type with
*no* method to generate one is pretty poor.

Actually, I would say that not having the ability to generate a UUID is
just fine. Most languages, have the ability to generate them per their
particular platforms. Let's leave it to them.

Sincerely,

Joshua D. Drake

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"Joshua D. Drake" <jd@commandprompt.com> writes:

Peter Eisentraut wrote:

The problem is that most of the standard methods are platform dependent, as
they require MAC addresses or a "good" random source, for instance. I'm not
sure how we wanted to solve that, but certainly leaving the uuid type with
*no* method to generate one is pretty poor.

Actually, I would say that not having the ability to generate a UUID is
just fine. Most languages, have the ability to generate them per their
particular platforms. Let's leave it to them.

Let us *not* open that can of worms for 8.3. This patch would not have
got in except that it didn't attempt to solve that problem, and there's
even less time available now.

regards, tom lane

On Tue, 2007-04-10 at 18:28 +0200, Peter Eisentraut wrote:

The problem is that most of the standard methods are platform dependent, as
they require MAC addresses or a "good" random source, for instance.

http://archives.postgresql.org/pgsql-patches/2007-01/msg00392.php

ISTM random() or similar sources is a sufficient PSRNG for the purposes
of UUID generation -- I can't see anything in the RFC that would
contradict that.

-Neil

Neil Conway wrote:

On Tue, 2007-04-10 at 18:28 +0200, Peter Eisentraut wrote:

The problem is that most of the standard methods are platform dependent, as
they require MAC addresses or a "good" random source, for instance.

http://archives.postgresql.org/pgsql-patches/2007-01/msg00392.php

ISTM random() or similar sources is a sufficient PSRNG for the purposes
of UUID generation -- I can't see anything in the RFC that would
contradict that.

How about we set up a contrib (I wish we'd fixed that) module with an
example function or two?

cheers

andrew

Neil Conway wrote:

On Tue, 2007-04-10 at 18:28 +0200, Peter Eisentraut wrote:

The problem is that most of the standard methods are platform dependent, as
they require MAC addresses or a "good" random source, for instance.

http://archives.postgresql.org/pgsql-patches/2007-01/msg00392.php

ISTM random() or similar sources is a sufficient PSRNG for the purposes
of UUID generation -- I can't see anything in the RFC that would
contradict that.

Maybe a short-term solution could be a UUID-generated function that
takes some kind of seed as a parameter. People not concerned about
collisons could just pass some random value, while others could use
the mac-address of the client or something similar.

greetings, Florian Pflug

Neil Conway <neilc@samurai.com> writes:

On Tue, 2007-04-10 at 18:28 +0200, Peter Eisentraut wrote:

The problem is that most of the standard methods are platform dependent, as
they require MAC addresses or a "good" random source, for instance.

http://archives.postgresql.org/pgsql-patches/2007-01/msg00392.php

ISTM random() or similar sources is a sufficient PSRNG for the purposes
of UUID generation -- I can't see anything in the RFC that would
contradict that.

Doesn't seem like quite enough bits of uniqueness.

We could improve matters by incorporating the database's
pg_control.system_identifier into the UUID, substituting for the MAC
address we don't have a good way to get. system_identifier is currently
determined by the system clock at initdb time (to gettimeofday
precision), so it would add at least some additional bits of
randomness...

regards, tom lane

# andrew@dunslane.net / 2007-04-10 15:49:08 -0400:

Neil Conway wrote:

On Tue, 2007-04-10 at 18:28 +0200, Peter Eisentraut wrote:

The problem is that most of the standard methods are platform dependent,
as they require MAC addresses or a "good" random source, for instance.

http://archives.postgresql.org/pgsql-patches/2007-01/msg00392.php

ISTM random() or similar sources is a sufficient PSRNG for the purposes
of UUID generation -- I can't see anything in the RFC that would
contradict that.

How about we set up a contrib (I wish we'd fixed that) module with an
example function or two?

Thought I'd mention Ralph Engelschall's uuid library, comes with
a PostgreSQL binding:

http://www.ossp.org/pkg/lib/uuid/
http://cvs.ossp.org/fileview?f=ossp-pkg/uuid/pgsql/uuid.txt&amp;v=1.1

I only played with it some time ago.

--
How many Vietnam vets does it take to screw in a light bulb?
You don't know, man. You don't KNOW.
Cause you weren't THERE. http://bash.org/?255991

On 4/10/07, Peter Eisentraut <peter_e@gmx.net> wrote:

The problem is that most of the standard methods are platform dependent, as
they require MAC addresses or a "good" random source, for instance.

FYI: good random source is already available in pgcrypto,
it uses either OpenSSL RAND_bytes() or internal strong PRNG.

--
marko

Sorry for this late reply....
I go work on the docs. What is the deadline on this... (have to
rearrange some other things...)

The roadmap lists mid-may for all patches to be reviewed and applied, so
for a docs patch I guess we'd like to have it early may at the latest.

(We'll still accept docs patches later, but I think only when they're more
along the lines of correction, not when it's a whole feature that's not
documented)

//Magnus

Gevik Babakhani wrote:

Sorry for this late reply....
I go work on the docs. What is the deadline on this... (have to
rearrange some other things...)

I've written some basic documentation. Please check
<http://developer.postgresql.org/pgdocs/postgres/datatype.html&gt; (in a
while) to see if I got everything right.

--
Peter Eisentraut
http://developer.postgresql.org/~petere/

Hi,

I think the basic description for the UUID datatype is okay. Perhaps we
could add some basic examples to the documentation later. Thank you.

Regards,
Gevik.