Re: primary key and existing unique fields - Mailing list pgsql-general

From Bruno Wolff III
Subject Re: primary key and existing unique fields
Date
Msg-id 20041027135534.GC3160@wolff.to
Whole thread Raw
In response to Re: primary key and existing unique fields  (Dawid Kuroczko <qnex42@gmail.com>)
List pgsql-general
On Wed, Oct 27, 2004 at 00:10:27 +0200,
  Dawid Kuroczko <qnex42@gmail.com> wrote:
> 3. If you'll need things like "last 50 keys", you can SELECT * FROM
> foo ORDER BY yourserialkey DESC LIMIT 50;

You really shouldn't be doing that if you are using sequences to generate
the key. Sequences are just guarenteed to return unique values, not to
return them in order. Because groups of sequences can be allocated to
a backend at once depending on a setting settable by a client, you can
get assignments out of order. Also for overlapping transactions what
the application means by the last 50 entries may not match what you
get when you get the 50 highest serial values.

pgsql-general by date:

Previous
From: Michael Glaesemann
Date:
Subject: Re: Changing access permissions without re-starting the database
Next
From: "Carlos Oliva"
Date:
Subject: Re: Changing access permissions without re-starting the database