In the previous chapters, we learned how to construct a T-SQL query, how SQL Server processes a query, and how the query is optimized, which results in an execution plan that can be cached and reused by subsequent query executions. Now that we understand the steps SQL Server follows to produce a plan and execute a query, we can investigate an execution plan to examine the results of this process and begin analyzing how we can improve the performance of our queries.
Query execution plans are often referred to as a showplan, which is a textual, XML, or graphical representation of the plan.
Think of a query execution plan as a map that provides information on the physical operators that implement the logical operations discussed in Chapter 1, Anatomy of a Query, as well as the execution context for that query, which provides information about the system...