Re: LOCALLY MANAGED EXTENT PERFORMANCE

From: Paul Drake <bdbafh_at_gmail.com>
Date: Tue, 26 Apr 2005 15:00:51 -0400
Message-ID: <910046b4050426120019ea7c56@mail.gmail.com>

On 4/26/05, Dogan, Ibrahim - Ibrahim <Ibrahim.Dogan_at_lowes.com> wrote:

>=20

> Ever heard "3 Party App" where you have no access to the code?

>=20

> I was also temped by the theory that number of extents don't matter much
> but I changed my mind after testing LMT with uniform extents for a 3.
> party app in which there are several tables that jump to 3-4G from 0
> bytes during day..all users started screaming and we had to go to LMT
> with auto allocate to calm down the users...

>=20

> You keep repeating yourself, telling well-known facts making it like I
> oppose them. I'm not saying uniform LMT is a bad thing. All I'm saying
> is it should be used if you know estimated size of tables. And even
> though LMTs reduces the extent allocation cost dramatically, there are
> some cases where thousands of extents may cause some headache..

>=20

> Even popular Oracle paper, "How to Stop Defragmenting and Start Living:
> The Definitive Word on Fragmentation", warns DBAs about excessive
> extents. Below is a clip from the paper:
> ...

The paper can still be found here:
http://metalink.oracle.com/metalink/plsql/showdoc?db=3DNOT&id=3D236895.1

I don't see the create_date of that paper listed, but I believe that 9i Release 1 had not yet been released yet. My very short point here is

Rather than chasing the tail of dog---ma, one should not assume that seminal papers that are based upon earlier versions are necessarily current.

"State your assumptions".

In much of Tom Kyte's recent postings, he mentions how having (reproducible) test cases alongside of text allows for verification of applicability of what was "proven" long ago as still being applicable to your current environment.

So I'm (possibly unfairly) sniping at one particular reference out of what may be an entirely valid post. ASSM (as well as possibly hundreds of 3 and 4 letter acronyms) was not around at all, when the paper that you refer to was authored.

Paul

#/etc/init.d/init.cssd stop
# f=3Dma, divide by 1, convert to moles.

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Received on Tue Apr 26 2005 - 15:09:55 CDT