Re: PG Admin - Mailing list pgsql-general

Your missing the point.

I am creating a design system for industrial control.

The control devices need to be numbered. The numbers need to be sequential.
If the user deletes a device the numbers need to regenerate to again become
sequential and gapless.

Bob
----- Original Message -----
From: "Scott Marlowe" <smarlowe@g2switchworks.com>
To: "Raymond O'Donnell" <rod@iol.ie>
Cc: "pgsql general" <pgsql-general@postgresql.org>
Sent: Monday, December 04, 2006 4:09 PM
Subject: Re: [GENERAL] PG Admin


> On Mon, 2006-12-04 at 17:53, Raymond O'Donnell wrote:
>> On 4 Dec 2006 at 15:40, Bob Pawley wrote:
>>
>> > When a row is deleted the serial number and oid are also deleted. The
>> > sequence then has gaps which are inadmissible.
>>
>> This is an issue which has come up at various times on this list in
>> the past - it may be worth having a look through the archives. Here's
>> one recent thread:
>>
>> http://archives.postgresql.org/pgsql-general/2006-08/msg00535.php
>
> Yeah.  The requirement for no gaps is a real no starter for any kind of
> large data set.
>
> Imagine modelling all the people in the US.  350 million entries.  No
> big deal.  I can create that in minutes.
>
> You each one give a number.  Again, no big deal.  A couple of minutes.
>
> For everyone that dies, you remove the name.  No big deal.  a couple
> seconds to run a delete.
>
> For every one that is born, you add it to the list, giving it the next
> number.  again, no big deal.  My workstation could probably handle the
> load.
>
> Now, turn that on its head.  Every time you delete someone, you have to
> renumber the data set, and for everyone added you have to make sure
> there are no gaps.
>
> Suddenly, you've got a problem that could bring even big iron to its
> knees.  All because some buearocrat (sp) hadn't the imagination to think
> of non-sequential numbering systems.
>
> While there are occasional systems where it is reasonable to actually
> have no sequential gaps, most of the time the only justification is "I
> don't like them."  If that is the case, you should rethink your design.
> If you're stuck with them because of some idiotic rule from on high,
> then at least abstract the numbers to some degree to improve performance
> and keep you from having to update about half of an entire table several
> times a minute.
>
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