Re: Normalized Databases = Poor Performance?

The mention of "silver bullets" automatically rings for me this bell, a classic paper by the author of the no less classic "Mythical Man Month":

www.lips.utexas.edu/ee382c-15005/Readings/Readings1/05-Broo87.pdf

(a useful reference for meetings).

The only cases when I have ever seen denormalization improving performance was when the database was far from being normalized in the very first place (and yet it was a slippery slope; two wrongs don't make one right). Not to say that MVs are totally useless; but you should consider them as an ETL process of sort, mainly that you have two different problems at hand that happen to use what superficially looks like the same data, but are indeed different representations of reality.

HTH Stéphane Faroult

Baumgartel, Paul wrote:

> I don't know if it's still around, but at 2004 IOUG in Toronto, there
> was a presentation that discussed the benefits of normalization in
> general, and normalization beyond 3NF in particular, which included
> /better/ performance.
>
> I regret that I didn't attend Hotsos this year, but I had just started
> a new job...
>
> *Paul Baumgartel*
> *CREDIT SUISSE*
> Information Technology
> DBA & Admin - NY, KIGA 1
> 11 Madison Avenue
> New York, NY 10010
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> Phone 212.538.1143
> paul.baumgartel_at_credit-suisse.com
> www.credit-suisse.com
>
> -----Original Message-----
> *From:* oracle-l-bounce_at_freelists.org
> [mailto:oracle-l-bounce_at_freelists.org]*On Behalf Of *Ethan Post
> *Sent:* Thursday, May 04, 2006 3:10 PM
> *To:* _oracle_L_list
> *Subject:* Normalized Databases = Poor Performance?
>
> In light of Jared's highly informative presention on why we should
> normalize for performance (Hotsos 2006) I was struck by this
> statement.
>
> http://www.quest-pipelines.com/newsletter-v7/newsletter_0406.htm
>
>
> Materialized views are an Oracle Silver Bullet when
> pre-joining tables together for super-fast response time.
>
> One issue with highly-normalized, non-redundant Oracle table
> designs (e.g. third normal form) is that Oracle experiences a
> high degree of overhead (especially CPU consumption) when
> joining dozens of tables together, over-and-over again.
>
> Using materialized views we pre-join the tables together,
> resulting in a single, fat, wide and highly-redundant table.
>
>
> Not trying to start a flame war or anything here! While there are
> certainly "truisms" in the statement above, it does seem to me at
> first glance to be a statement that feeds into the "normalization
> hurts performance" mindset.
>
>
> I have not read the entire article yet.
>
> Thanks,
> Ethan
>
>
>
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