Chapter 63. Interpreting Query Execution Plans


  • The language of performance tuning and optimization

  • Viewing, saving, and working with query execution plans

  • Reading query execution operators

I believe that intelligence is the ability to abstract—to create something new at a higher lever based on more primitive constructs. The ability to express thoughts using words composed of letters and simple sounds is abstraction; to turn beats and notes into a melody is abstraction; and to turn 1s a 0s in CPU registers into a programming language and then use that language to develop an application represents multiple layers of abstraction.

Interpreting SQL Server query execution plans is abstraction inside-out.

SQL, as a declarative language, is an interesting study of abstraction because the underlying primitive operations that execute the query are dynamically determined based on more than just the SQL query.

The art of SQL Server performance tuning and optimization (PTO) is essentially the skill of reading the query execution plans and understanding how to manipulate the factors that determine the physical operations in an effort to improve performance. The operations inside a query execution plan are the language of SQL Server PTO, which is why this part of the book begins with reading and interpreting the query execution plan.

Viewing Query Execution Plans

The SQL Server development team has exposed the query execution plan in several places and in several formats, making it easy ...

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