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Re: Rollback segments

From: <plomax_at_oriolecorp.com>
Date: Fri, 04 Sep 1998 09:37:17 +0100
Message-ID: <35EFA6BD.3D73F9A2@oriolecorp.com>


Hi,
just a little info here.
You can look at the problem in several ways. More than one way to eat a hard boiled egg.
1. Select/Insert with out rollbacks yes this is possible. You can perform even parallel select's where you can determine how many processes you wish to use in function with how many CPU's you have. bla bla The aim would be to use SQL Loader with direct path and unrecoverable options. When you extract think about could I put this to an ASCII file or even pipe this to another process.
An article on this is at www.oriolecorp.com under PDQOUT.

2. Server concepts explain the function of the rollbacks
3. Not a good idea
4. Try what has been suggested earlier. What I do is provide a tool for my
developers which allows them to calculate how many rows before a commit. In a nutshell:
If I have a row that is on average 2k x 5000 rows processed will be roughly 10MB. So keep you rbs at 10MB
Inversely my rollback are 10MB how many rows do the developers treat before a commit. Calculate the length and then ....

Cheers
Peter Lomax

Kevin Gray wrote:

> Hi there
>
> I am writing some SQL scripts with Unix shell as well to do some very large
> updates (could be moving 3.5million records in insert/select combination).
>
> Can anyone provide answers to the following.
>
> 1. Is it possible to have a single insert/select run without requiring a
> rollback segment to use?
> 2. Is it possible to use multiple rollback segments for a single
> insert/select transaction?
> 3. Is it possible to use multiple files in a single rollback segment so
> that the rollback segment can be split over several files and, possibly,
> disks?
>
> Also, does anyone know exactly the best way to work out how much space to
> allow for rollback segments.
>
> Any help would be very much appreciated.
>
> Thanks.
>
> Regards
>
> Kevin Gray
>
> Kevin Gray
> Senior Consultant
> The Customer Engagement Company, UK
> Email: kevin.gray_at_h2engage.co.uk
> WWW: http://www.h2engage.co.uk/
Received on Fri Sep 04 1998 - 03:37:17 CDT

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