Re: Table and index Extent Sizing ?

From: Niall Litchfield <n-litchfield_at_audit-commission.gov.uk>
Date: Mon, 26 Feb 2001 13:33:26 -0000
Message-ID: <97dlv7$77o$1@soap.pipex.net>

firstly this is a FAQ.

Answer to question 1. Lots of people have various algorithms for computing initial,next pctfree, pctused etc. They are pretty much all irrelevant.

Answer to question 2. No.

The reason for these two answers:

You should organise your data into tablespaces with UNIFORM extent sizing. so you might have one tablespace with 128k extents and one with 4m extents. The reason for doing this is so that you eliminate fragmentation entirely. In addtion of course you will still want to split data and indexes and probably also based on different io requrements.

It is of course true that you may want to set PCTFree and PCTused to non-default values, but I'd at least try them (in development) and see if chaining and migration occur before changing the defaults.

regards

--
Niall Litchfield
Oracle DBA
Audit Commission UK
"yakub" <yakub_at_erols.com> wrote in message
news:3A9A4C0B.9C1BBFDA_at_erols.com...


> I have updated an algorythm that computes the initial and next extents

> with respect to space management of data and indexes .  That is, I

> compute for the Space Available for Data (SAD)  based on average

> rowsize, PctFree and blocksize.

>

> Question 1: Does anyone have an algorthym that can be used to compute

> the initial and next extents sizes?

> Question 2:  Should one also strive to get all of the data into one

> extent?

>

> Please explain.

> Thanks,

> Yakub

>

Received on Mon Feb 26 2001 - 07:33:26 CST