Inside Microsoft® SQL Server™ 2005: Query Tuning and Optimization

Analyzing Plans

To really understand query plans and to really be able to spot, fix, or work around problems with query plans, we need a solid understanding of the query operators that make up these plans. All in all, there are too many operators to discuss them in one chapter. Moreover, there are innumerable ways to combine these operators into query plans. Thus, in this section, we focus on understanding the most common query operators—the most basic building blocks of query execution—and give some insight into when and how SQL Server uses them to construct a variety of interesting query plans. Specifically, we will look at scans and seeks, joins, aggregations, unions, a selection of subquery plans, and parallelism. With an understanding of ...