Refactoring Databases: Evolutionary Database Design (Hardcover)

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Editorial Reviews

Product Description

Refactoring has proven its value in a wide range of development projects--helping software professionals improve system designs, maintainability, extensibility, and performance. Now, for the first time, leading agile methodologist Scott Ambler and renowned consultant Pramodkumar Sadalage introduce powerful refactoring techniques specifically designed for database systems. Ambler and Sadalage demonstrate how small changes to table structures, data, stored procedures, and triggers can significantly enhance virtually any database design--without changing semantics. You'll learn how to evolve database schemas in step with source code--and become far more effective in projects relying on iterative, agile methodologies. This comprehensive guide and reference helps you overcome the practical obstacles to refactoring real-world databases by covering every fundamental concept underlying database refactoring. Using start-to-finish examples, the authors walk you through refactoring simple standalone database applications as well as sophisticated multi-application scenarios. You'll master every task involved in refactoring database schemas, and discover best practices for deploying refactorings in even the most complex production environments. The second half of this book systematically covers five major categories of database refactorings. You'll learn how to use refactoring to enhance database structure, data quality, and referential integrity; and how to refactor both architectures and methods. This book provides an extensive set of examples built with Oracle and Java and easily adaptable for other languages, such as C#, C++, or VB.NET, and other databases, such as DB2, SQL Server, MySQL, and Sybase. Using this book's techniques and examples, you can reduce waste, rework, risk, and cost--and build database systems capable of evolving smoothly, far into the future.

From the Back Cover

Refactoring has proven its value in a wide range of development projects–helping software professionals improve system designs, maintainability, extensibility, and performance. Now, for the first time, leading agile methodologist Scott Ambler and renowned consultant Pramodkumar Sadalage introduce powerful refactoring techniques specifically designed for database systems.

Ambler and Sadalage demonstrate how small changes to table structures, data, stored procedures, and triggers can significantly enhance virtually any database design–without changing semantics. You’ll learn how to evolve database schemas in step with source code–and become far more effective in projects relying on iterative, agile methodologies.

This comprehensive guide and reference helps you overcome the practical obstacles to refactoring real-world databases by covering every fundamental concept underlying database refactoring. Using start-to-finish examples, the authors walk you through refactoring simple standalone database applications as well as sophisticated multi-application scenarios. You’ll master every task involved in refactoring database schemas, and discover best practices for deploying refactorings in even the most complex production environments.

The second half of this book systematically covers five major categories of database refactorings. You’ll learn how to use refactoring to enhance database structure, data quality, and referential integrity; and how to refactor both architectures and methods. This book provides an extensive set of examples built with Oracle and Java and easily adaptable for other languages, such as C#, C++, or VB.NET, and other databases, such as DB2, SQL Server, MySQL, and Sybase.

Using this book’s techniques and examples, you can reduce waste, rework, risk, and cost–and build database systems capable of evolving smoothly, far into the future.

 

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Product Details

• Hardcover: 384 pages
• Publisher: Addison-Wesley Professional (March 13, 2006)
• Language: English
• ISBN-10: 0321293533
• ISBN-13: 978-0321293534
• Product Dimensions: 9.4 x 6.9 x 1.1 inches
• Shipping Weight: 1.9 pounds (View shipping rates and policies)
• Average Customer Review: 4.4 out of 5 stars  See all reviews (22 customer reviews)
• Amazon.com Sales Rank: #42,948 in Books (See Bestsellers in Books)

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• This item is part of The Signature Series.

Customer Reviews

Most Helpful Customer Reviews

30 of 33 people found the following review helpful:

5.0 out of 5 stars Excellent refactoring reference and eye-opening book, May 8, 2006

By	Michael Cohn "agile developer" (Lafayette, CO USA) - See all my reviews (REAL NAME)

This is an excellent book that, in my opinion, serves two purposes. First, it is a compendium of well thought-out ways to evolve a database design. Each refactoring includes descriptions of why you might make this change, tradeoffs to consider before making it, how to update the schema, how to migrate the data, and how applications that access the data will need to change. Some of the refactorings are simple ones that even the most change-resistant DBAs will have used in the past ("Add index"). Most others (such as "Merge tables" or "Replace LOB with Table") are ones many conventional thinking DBAs avoid, even to the detriment of the applications their databases support.

This brings me to the second purpose of this book. Many DBAs view their jobs as protectors of the data. While that is admirable, they sometimes forget that they are part of a software development team whose job is to provide value to the organization through the development of new (and enhancement of existing) applications. One of the best DBAs I ever worked with viewed himself as a "Data Valet." He said his job was to make sure the data was presented to applications when and where they wanted and to protect the doors from getting dinged while under his care. Through its first five chapters and then the refactorings that follow, this book will help DBAs expand their view of their role in the organization from one of simply protecting data to one of enhancing the value of data to the organization.

This book is one that you'll keep on your reference shelf for many years to come. Highly recommended.

6 of 6 people found the following review helpful:

5.0 out of 5 stars Finally!, April 5, 2006

By	Base Aware "Base Aware" (Toronto, ON Canada) - See all my reviews

It's been almost 7 years since Fowler's Refactoring book, and now the database community has finally caught up with the rest of us. This book shows how to refactor a relational database schema, working you through the detailed process steps for doing so and providing the source code for implementing more database refactorings than I would have thought existed.

The first five chapters describe how to go about database refactoring. Chapter 1 overviews the idea that you can evolve your database schema in small steps, a radical departure for many traditional DBAs. It also overviews the need for supporting techniques such as agile data modeling, database regression testing, and version control of your data models and scripts. I would have liked to see more coverage of these topics, but at least the modeling material is covered in Ambler's Agile Modeling book and there are some great SCM books out there.

Chapters 2 and 3 walk through the process of implementing a database refactoring, first through the simple situation where there is only a handful of applications accessing the database. I guess this sort of thing happens in smaller companies, but most of the time you really have to worry about scores of applications accessing your database which is a much harder situation. This is actually the focus of Chapter 3 and of the presented solutions in Chapters 6 through 11 which provide reference implementations for all of the database refactorings. This approach belies the true strength of the book: it reflects actual experience in large organizations, not just the theoretical pie in the sky stuff you see from other authors.

Chapter 4 focuses on deploying database refactorings in production, providing detailed instructions for how to roll refactorings between various sandboxes. It importantly describes how to merge the refactorings of several teams together. If you have 100 applications accessing a shared database, then potentially you need to manage the refactorings coming from 100 different development teams. Of course it would never be that bad, but even merging refactorings from 10 teams would be tough. This might be where the technique falls apart because many companies likely don't have data managers who are skilled enough to do this sort of thing efficiently enough to keep up with agile developers. We need new tools, so hopefully companies like Oracle will build something for us.

Chapter 5 describes a collection of best practices and challenges pertaining to refactoring databases. The authors share their experiences as well as identify potential issues, such as a lack of tooling and agile expertise within the data community, that could slow adoption of this technique. My guess is that the smarter teams within companies will start doing this stuff right away, for the most part it's pretty easy technically, but that bigger companies will struggle to change as they always do.

Chapters 6+ are reference descriptions for the individual refactorings. Each one is described using a UML data model, which is a little strange at first although once you get used to it you can see how it's a much better notation than Crow's feet, a detailed text description and source code. The source code examples are detailed, I guess the authors want to be thorough and provide a complete solution so that there's no question how to implement each refactoring. The application examples are written in Java or Hibernate, but they're simple enough that you could see how to implement them in C#, C++, Ruby, or even VB. The database code is Oracle, once again it's pretty straightforward so you can easily see how it would work in other DBs like Sybase or MySQL.

All in all, if you're a DBA or agile programmer you need to seriously think about buying this book.

11 of 13 people found the following review helpful:

3.0 out of 5 stars on the right path, November 17, 2006

By	arzewski (pittsburgh, pa United States) - See all my reviews

This book is a much needed exploration on the subject. It tries to categorize those operations that developers and DBAs do on a database, who, for various reasons, must address a specific problem, need. I only gave it three stars because it is somewhat insufficient. It also doesn't make much of a distinction between a database in development and one in production. In the latter case, it is really difficult to make changes when there is already a data structure in place with data, being updated constantly by users, and plans to migrate to a different data model while a system is in production is really not for the faint of heart. What I am really loooking for is a thick book of bad designs that, for various reasons (unclear or evolving requirements, political), a database model presents itself with a bunch of problems, real problems and not just theoretical, and the ways a DBA and developers came about after a big pow-wow on how to solve it.