What Is a Cost-Based Optimizer?

When you execute a query, the database server has to figure a lot of things out. For even the simplest queries, there are usually several possible ways to get the job done.

Missing Indexes

Execution Plans and Data Protection

One of the most important tools for query tuning is ability to view execution plans. They are even portable; you can send an execution plan to get advice from someone who doesn't have access to the underlying data. Have you even considered that sensitive information might travel along with the plans? Hugo Kornelis explains how execution plans affect data protection.

How to Show the Execution Plan of a Running Query

By looking at a query execution plan, you can determine which steps are used to resolve the query. But what if you just want to find out what the query plans are for only the queries that are currently running?

Why sp_prepare Isn’t as “Good” as sp_executesql for Performance

Erik Darling shows how execution plan estimates suffer.

Properly Persisted Computed Columns

Paul White walks through a new trace flag in SQL Server 2016 designed to yield better execution plans (and performance) for queries involving computed columns.

Office Hours Webcast 2017/02/01

In this edition of Office Hours, Brent, Erik, and Richie discuss AlwaysOn Availability Groups, execution plans, speeding up log shipping, applying wrong service packs, their favourite high availability solutions, and more.

Determining What Happens When You Force an Execution Plan via the Query Store

When you force a query plan via the Query Store, you will need to track what happens: Sometimes the request to force a plan will fail, and you will want to know when and why. There are several ways of getting feedback, ranging from the built-in reports to using extended events. Enrico explains the details.

SQL Server Execution Plans, Second Edition by Grant Fritchey

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. This 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.

Comparing Execution Plans