Book Image

Microsoft SQL Server 2012 Performance Tuning Cookbook

Book Image

Microsoft SQL Server 2012 Performance Tuning Cookbook

Overview of this book

As a DBA you must have encountered a slow running application on SQL Server, but there are various factors that could be affecting the performance. If you find yourself in this situation, don't wait, pick up this book and start working towards improving performance of your SQL Server 2012. SQL Server 2012 Performance Tuning Cookbook is divided into three major parts -- Performance Monitoring, Performance Tuning, and Performance Management--that are mandatory to deal with performance in any capacity. SQL Server 2012 Performance Tuning Cookbook offers a great way to manage performance with effective, concise, and practical recipes. You will learn how to diagnose performance issues, fix them, and take precaution to avoid common mistakes. Each recipe given in this book is an individual task that will address different performance aspects to take your SQL Server's Performance to a higher level.The first part of this book covers Monitoring with SQL Server Profiler, DTA, System statistical function, SPs with DBCC commands, Resource Monitor & Reliability, and Performance Monitor and Execution Plan. The second part of the book offers Execution Plan, Dynamic Management Views, and Dynamic Management Functions, SQL Server Cache and Stored Procedure Recompilations, Indexes, Important ways to write effective TSQL, Statistics, Table and Index Partitioning, Advanced Query tuning with Query Hints and Plan Guide, Dealing with Locking, Blocking and Deadlocking and Configuring SQL Server for optimization to boost performance.The third and final part gives you knowledge of performance management with help of Policy Based Management and Management with Resource Governor.
Table of Contents (28 chapters)
Microsoft SQL Server 2012 Performance Tuning Cookbook
Credits
About the Authors
Acknowledgement
Acknowledgement
About the Reviewers
www.PacktPub.com
Preface
Index

Introducing Key Lookups, finding them in execution plans, and resolving them


Key Lookup is a bookmark lookup on a table with a clustered index. Key Lookup is used by SQL Server while retrieving information regarding non-key column. All the queries that use non-clustered index wouldn't have Key Lookup but all Key Lookup occurrences are accompanied by a non-clustered index. One more thing to remember is that Key Lookup always enjoys the company of Nested Loop operator.

Getting ready

We are going to create a table to see different effects of Key Lookup operator in execution plan. In order to generate the case of Key Lookup, we need two essential things to be present on the table:

  • Clustered index

  • Non-clustered index

When you have predicate based on key field of non-clustered index, which meets seek on the same index and goes to clustered index to retrieve the data for non-key field of non-clustered index, it generates Key Lookup, which we will achieve by creating SalesOrdDetailDemo table...