Microsoft® SQL Server® 2008 Internals

Chapter 8. The Query Optimizer

Conor Cunningham

The Query Optimizer in Microsoft SQL Server 2008 determines the query plan to be executed for a given SQL statement. Because the Query Optimizer does not have a lot of exposed features, it is not as widely understood as some of the other components in the SQL Server Engine. This chapter describes the Query Optimizer and how it works. After reading this chapter, you should understand the high-level optimizer architecture and should be able to reason about why a particular plan was selected by the Query Optimizer. By extension, you should be able to troubleshoot problem query plans in the case when the Query Optimizer may not select the desired query plan and how to affect that selection.

This chapter ...