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Paul Nielsen

Another Reason to Normalize

Database can be measured by six properties – four determined by the design; Usability, Integrity, Performance/Scalability, and Extensibility; and two being more a function of implementation than design; Availability and Security.

Of these six factors, I’d argue that in the long run, extensibility is the one that is more expensive to repair. All six are necessary, but a database that has become brittle (touch one thing, everything else breaks) is either impossible or extremely expensive to correct. Database extensibility is bought with three techniques; a strongly enforced data abstraction layer, data driven design, and normalization. Normalization is typically credited with the integrity of the database, and this is true. But normalization also influences the extensibility of the database. Here’s why,

A poorly designed, anti-normalized database is typically made to work using multiple layers of convoluted code. It takes a lot of extra code to keep anti-normalized data consistent. All this code is more expensive to maintain, and makes it very difficult to implement changes and new features.

It’s not even a factor of pay-me-now or pay-me-later. An anti-normalized database doesn’t just cost a bit more to fix later; it costs so much to fix later that companies, or careers, fail due to the poor design. The bottom line is still that a man-day spent on database design saves, at least, a man-month of extra work later.

Published Tuesday, October 16, 2007 1:48 PM by Paul Nielsen



Boris said:

True.  Alas, if I had a nickel of for every database that can be highly evaluated on all six properties, I would be...  dirt poor ;)

November 3, 2007 12:40 PM
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About Paul Nielsen

Paul Nielsen believes SQL is the romance language of data. As such he’s a hands-on database developer, Microsoft SQL Server MVP, trainer, and author of SQL Server Bible series (Wiley). As a data architect, he developed the concepts of Smart Database Design and Nordic – an open source O/R dbms for SQL Server. He lives in Colorado Springs.

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