Normalization

From: Paul Baumgartel <treegarden_at_yahoo.com>
Date: Thu, 29 Jul 2004 08:32:22 -0700 (PDT)
Message-ID: <20040729153222.50566.qmail@web13421.mail.yahoo.com>

I'd love to hear comments on the following Q&A (by a well-known Oracle "expert"). Do list members think that this view prevails today? Am I correct in believing that the importance of normalization, and the reasons for that importance, are given short shrift by many DB designers?

Q: What are the basic guidelines one should keep in mind while designing a database? Is denormalization always good?

I used to teach database design in graduate school, and your question is excellent! The main purpose of high normalization was the reduction of disk space, back when it mattered in the 1970s.

Today, I always introduce redundancy into the model whenever it can eliminate an SQL join, but not always. I make my decision based on two criteria:

1 – The size of the redundant item

2 – The volatility of the item (e.g. how often do I need to duplicate updates)

Paul Baumgartel
Transcentive, Inc.
www.transcentive.com

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Received on Thu Jul 29 2004 - 10:29:54 CDT