[From O'Reilly & Associates, Inc.
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
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."
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