Book Image

Learn T-SQL Querying - Second Edition

By : Pedro Lopes, Pam Lahoud
Book Image

Learn T-SQL Querying - Second Edition

By: Pedro Lopes, Pam Lahoud

Overview of this book

Data professionals seeking to excel in Transact-SQL (T-SQL) for Microsoft SQL Server and Azure SQL Database often lack comprehensive resources. This updated second edition of Learn T-SQL Querying focuses on indexing queries and crafting elegant T-SQL code, catering to all data professionals seeking mastery in modern SQL Server versions and Azure SQL Database. Starting with query processing fundamentals, this book lays a solid foundation for writing performant T-SQL queries. You’ll explore the mechanics of the Query Optimizer and Query Execution Plans, learning how to analyze execution plans for insights into current performance and scalability. Through dynamic management views (DMVs) and dynamic management functions (DMFs), you’ll build diagnostic queries. This book thoroughly covers indexing for T-SQL performance and provides insights into SQL Server’s built-in tools for expedited resolution of query performance and scalability issues. Further, hands-on examples will guide you through implementing features such as avoiding UDF pitfalls, understanding predicate SARGability, Query Store, and Query Tuning Assistant. By the end of this book, you‘ll have developed the ability to identify query performance bottlenecks, recognize anti-patterns, and skillfully avoid such pitfalls.
Table of Contents (18 chapters)
1
Part 1: Query Processing Fundamentals
4
Part 2: Dos and Don’ts of T-SQL
9
Part 3: Assembling Our Query Troubleshooting Toolbox

Summary

This chapter covered the important topic of storing query performance statistics in the flight recorder, which is the Query Store, which allows us to access query plans and their runtime statistics, along with how they change over time. With what we’ve learned so far in all the previous chapters of this book (especially in Chapter 3, Exploring Query Execution Plans, about what information lies inside query plans), we can now more easily find resolutions for performance problems. We can easily identify plans that must be tuned, or for quick mitigation, just return to a known good plan that had been stored in Query Store. We also learned how the Query Store enables several helpful features that allow the Query Optimizer to automatically detect and correct common query performance issues.

Finally, we covered how to use either system views or SSMS to uncover the highest resource-consuming queries executing in our databases and help us quickly find and fix query performance...