SQL Tuning [Electronic resources] نسخه متنی

Chapter 4. Controlling Execution Plans

Saying is one thing and doing is another.

Michel Eyquem de Montaigne Essays, Bk. II, Ch. 31

This chapter covers two classes of tuning techniques for controlling
execution plans: universal techniques that work independently of your
choice of database vendor, and techniques that are database-specific.
Database-specific techniques are covered well by your own
vendor's documentation, so you might know them well
already. In general, you need both types of techniques to get
precisely the execution plan you want. Each of the vendor-specific
sections stands alone, even repeating material from the other
sections when applicable. Therefore, you can skip the vendor sections
that you don't need.

Much ado has been made over controlling execution plans, sometimes
with elaborate tools. This chapter focuses on the simplest ways to
control plans, with a strong emphasis on getting the types of plans
you will need to optimize real-world SQL. I have found that when you
know which execution plan you want in advance, getting it is easy and
requires only simple tools.