Re: How to determine size(storage) of a table with indexes?

From: Daniel Nichols <daniel.nichols_at_NOSPAMvirgin.net>
Date: Tue, 10 Jun 2003 19:34:32 +0000 (UTC)
Message-ID: <20dcevgf5t6r88a3eqh7moja6ijvkh65mr@4ax.com>

Yes, there are formulas - they're just not very good. If you don't have a development database then perhaps you would resort to them as a guide.

The current 8i guide just goes on about estimating now because this is the best way.
Oracle8i Administrator's Guide - 13 Managing Tables - Estimate Table Size and Set Storage Parameters

The Oracle 7 manual - 8 Managing Schema Objects used to follow the advice on estimating with calculating space required by non-cluster tables. This was done by solving simultaneous equations. In the case of indexes it included gems like "now times that number by 1.05 to add an additional 5% of space"!

I think there is a reason this documentation has not been continued!

If we're using local managed tablespace you don't really need to care anymore how big the table's going to be as long as you have space. You just need the ball-park figure.

There are loads of papers on this.

My use is:

Tablespaces should be decided upon based on

·	Extent size requirement of objects
·	Comparable I/O pattern of objects
·	Recovery concerns - can the tablespace be taken offline while

the rest of the database is still available and still be of value to users

It is common for Tablespaces to be created for particular schemas or business use though this logical partitioning is not strictly necessary.

Here are three size categories of tablespaces to use.

size        Extent size       Table size range
small	 128KB              0 - 128MB
medium  4MB                 128MB - 4GB
large       128MB            4GB > MB
		

If you table is 2GB stick it in a medium tablespace.

On Tue, 10 Jun 2003 00:47:04 +0200, "Sybrand Bakker" <postbus_at_sybrandb.demon.nl> wrote:

>
>"Daniel Nichols" <daniel.nichols_at_NOSPAMvirgin.net> wrote in message
>news:iks9evglpl16l6mu59tj91d25fr9tjthh7_at_4ax.com...
>> Use something like the following to get the table with some sample
>> rows in it then multiple it up to your requirements. It's best to do
>> this empirically then use pencil and paper.
>>
>There are formulas for this and they are documented.
Received on Tue Jun 10 2003 - 14:34:32 CDT