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Re: How taxing are constraints?

From: Will Kooiman <wkooiman_at_csac.com>
Date: 1997/05/29
Message-ID: <338E4A76.1A24@csac.com>#1/1

Most constraints have negligible performance degradations. I would be surprised if you could measure the performance impact of adding NOT NULL on a few columns.

However, if you are stuffing spaces into a column simply to get around a NOT NULL constraint, you WILL see a performance degradation. Oracle stores null values very efficiently. I've seen systems that have NOT NULL on every column use 3 times the storage as they did otherwise.

David Kramer wrote:
>
> We're redesigning some of our tables. Most fields in most tables should
> not have NULL values. The project is big, but there are only a few
> programmers.
>
> How much would the system be taxed if I defined those fields as NOT NULL?
> Is it negligible, or should I only use it for keys, etc?
>
> By way of background, it's a web-based product using oraperl5 on a Sparc
> 20.

Will.

-- 
======================================================================
Will Kooiman                        Computer Systems Authority
Systems Consultant                  6380 LBJ Freeway, Suite 181
(972) 960-0180 x236                 Dallas, TX 75240
mailto:wkooiman@csac.com            http://www.csac.com
Received on Thu May 29 1997 - 00:00:00 CDT

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