Sebastopol, CA--Early on, Dan Tow, author of the just-released "SQL Tuning" (O'Reilly, US $39.95) realized that the biggest factor in the performance of a business application is the speed of the SQL it runs. It took him a little longer to realize just how much room for improvement typically lies in that SQL--in fact, that the SQL that most affects the load on a system and the productivity of its end users can usually be improved by a large factor, often by a factor of two or more. The problem was finding reliable guidance on just how to tune SQL.
There are two basic issues that most people focus on when tuning SQL: how to find and interpret the execution plan of an SQL statement and how to change SQL to get a specific alternate execution plan. Tow provides the answers to these questions in "SQL Tuning" and addresses a third, even more critical question: How do you decide which execution plan a query should use?
The process involved is usually one of frustrating trial and error. As Tow explains, "Since real business-application queries can easily offer billions of alternative execution plans, tuning without a systematic method to choose your target execution plan is hopelessly inefficient. The problem is akin to finding yourself lost in strange city without a map: working eyes and legs are not enough to take you where you need to go."
The article continues at http://press.oreilly.com/pub/pr/1123
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