Bøger af Grant Fritchey

Troubleshoot slow-performing queries and make them run faster. Database administrators and SQL developers are constantly under pressure to provide more speed. This new edition has been redesigned and rewritten from scratch based on the last 15 years of learning, knowledge, and experience accumulated by the author. The book Includes expanded information on using extended events, automatic execution plan correction, and other advanced features now available in SQL Server. These modern features are covered while still providing the necessary fundamentals to better understand how statistics and indexes affect query performance.The book gives you knowledge and tools to help you identify poorly performing queries and understand the possible causes of that poor performance. The book also provides mechanisms for resolving the issues identified, whether on-premises, in containers, or on cloud platform providers. You'll learn about key fundamentals, such as statistics, data distribution, cardinality, and parameter sniffing. You'll learn to analyze and design your indexes and your queries using best practices that ward off performance problems before they occur. You'll also learn to use important modern features, such as Query Store to manage and control execution plans, the automated performance tuning feature set, and memory-optimized OLTP tables and procedures. You will be able to troubleshoot in a systematic way. Query tuning doesn't have to be difficult. This book helps you to make it much easier.What You Will LearnUse Query Store to understand and easily change query performanceRecognize and eliminate bottlenecks leading to slow performanceTune queries whether on-premises, in containers, or on cloud platform providersImplement best practices in T-SQL to minimize performance riskDesign in the performance that you need through careful query and index designUnderstand how built-in, automatic tuning can assist your performance enhancement effortsProtect query performance during upgrades to the newer versions of SQL ServerWho This Book Is ForDevelopers and database administrators with responsibility for query performance in SQL Server environments, and anyone responsible for writing or creating T-SQL queries and in need of insight into bottlenecks (including how to identify them, understand them, and eliminate them)

Intermediate-Advanced user level

If a query is performing poorly, and you can't understand why, then that query's execution plan will tell you not only what data set is coming back, but also what SQL Server did, and in what order, to get that data. It will reveal how the data was retrieved, and from which tables and indexes, what types of joins were used, at what point filtering, sorting and aggregation occurred, and a whole lot more. These details will often highlight the likely source of any problem. I wrote this book with the singular goal of teaching you how to read SQL Server Execution plans It will explain, among many other things, the following: How to capture execution plans using manual and automatic methodsA documented method for reading and interpreting execution plansHow common SQL Server objects, such as indexes, views, stored procedures, and so on, appear in execution plansHow to control execution plans with hints and plan guides, and why this is a double-edged swordHow the Query Store works with, and collects data on, execution plans With this knowledge, you'll have everything you need to read the execution plan, for any query of your own, regardless of complexity, and understand what it does and what is causing the bad performance. It is still your job to work out how best to fix it, but your new understanding of execution plans will give a much better chance of success!

Every day, out in the various online forums devoted to SQL Server, and on Twitter, the same types of questions come up repeatedly: Why is this query running slowly? Why is SQL Server ignoring my index? Why does this query run quickly sometimes and slowly at others? My response is the same in each case: have you looked at the execution plan? An execution plan describes what's going on behind the scenes when SQL Server executes a query. It shows how the query optimizer joined the data from the various tables defined in the query, which indexes it used, if any, how it performed any aggregations or sorting, and much more. It also estimates the cost of all of these operations, in terms of the relative load placed on the system. Every Database Administrator, developer, report writer, and anyone else who writes T-SQL to access SQL Server data, must understand how to read and interpret execution plans. My book leads you right from the basics of capturing plans, through how to interrupt them in their various forms, graphical or XML, and then how to use the information you find there to diagnose the most common causes of poor query performance, and so optimize your SQL queries, and improve your indexing strategy.

Put the principles and lessons from SQL Server 2012 Query Performance Tuning into practice today. Establish performance baselines and monitor against them Troubleshoot and eliminate bottlenecks that frustrate users Plan ahead to achieve the right level of performance