Preface

This book covers query tuning and optimization in SQL Server and provides you with the tools and knowledge necessary to get peak performance from your queries and applications. We mostly relate query optimization with the work performed by the query optimizer in which an efficient execution plan is produced for a query. However, sometimes we may not be happy with the query execution performance and may try to improve it by performing additional changes—or what we call query tuning. But even more important, we need to understand that the results we originally get from the query optimizer will greatly depend on all the information we feed it—for example, our database design, the defined indexes, and even some database and server configuration settings.

There are many ways in which we can impact the work performed by the query processor, which is why it is extremely important to understand how we can help this SQL Server component do a superior job. Providing quality information to the query processor will most likely result in high-quality execution plans, which will also improve the performance of your databases. But no query processor is perfect, and it is important to understand the reasons why sometimes we may not, in fact, get an efficient execution plan or good query performance and to know what possible solutions are still available.

Finally, this book covers all the supported versions of SQL Server and has been updated up to SQL Server 2022.