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Wednesday, July 22, 2009

Book Review: Agile Database Techniques

I've decided to read a technical book every two weeks. You out there in tubeland will benefit by getting a book review every (roughly) two weeks. Here's the first, a book that I carried around with me for months meaning to read and finally decided I had to do it because there's a bunch more I want to read, too:

Effective Strategies for the Agile Software Developer
by Scott W. Ambler

The main theme of this book is the impedence mismatch between the traditional management of relational databases and increasingly agile software development, which somewhat mirrors that which exists between an RDBMS and an object-oriented software design. The basic premise is that DBAs still largely tend to define the entire database schema at the very beginning of a project and make it difficult to change, whereas developers are now largely accepting of the fact that software has to evolve instead of being fully designed up front. Some topics are covered because they relate directly to the main theme, and others are geared toward giving DBAs a basic understanding of and common vocabulary with modern software development and developers. Still others, such as the data normalization chapter, strive to do just the reverse for developers--give them a better understanding of the database side of the house. Overall, the author tries to bring DBAs and developers into a common ground where both are aware of the issues that the other must deal with and at the same time urge database professionals to adapt to Agile development, as the future is clearly one of an evolutionary approach to software.

Many of the chapters in this book are essential knowledge for an enterprise developer; however, it was published in 2003, and many concepts that were novel at that time are now taken as a matter of course, so you may already be familiar with much of it. For instance, if you have a good knowledge of Hibernate, you probably won't get much out of the chapters Object-Relational Impedance Mismatch (Chapter 7) or Mapping Objects to Relational Databases (Chapter 14), although they contain fairly important foundational knowledge. A good deal of the material in the book is like this, and it has quite a broad reach, dealing with topics from test-driven development to data normalization to UML.

The book is liberally sprinkled with real-world examples and practical advice. It comes through clearly that Ambler has been there and done that. There's also one chapter that covers a topic that hasn't gained much traction even today: database refactoring. The idea in this chapter is to attempt to loosely apply the idea of code refactoring--"a disciplined technique for restructuring an existing body of code, altering its internal structure without changing its external behavior"--to the database to allow for more evolutionary database approaches even in the cases where multiple systems interact with one database. Ambler gives good examples that demonstrate why and when database refactorings are appropriate, and there is a catalog of established refactorings in the Appendix.

All things considered, I'd highly recommend this book for reading by junior developers. More senior ones should skim through it to be sure they're at least conversant on all the topics covered, as they are all very much relevant today.

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