Query Optimizer Suggests Wrong Index and Query Plan -- Why?

A good example where the Query optimizer picks the wrong query plan and suggested index.

How to Confuse the SQL Server Query Optimizer

Want to 'trick' SQL Server into performing millions of logical reads to return data, when only are few thousand were really required? In this article, Gail Shaw examines three common forms of generic SQL that can and will confuse the SQL Server Optimizer to the point that it generates and reuses very inefficient execution plans.

Importance of Statistics and How It Works in SQL Server – Part 1

SQL Server Query Optimizer uses statistical information to estimate the cardinality in a query result. This enables the SQL Server Query Optimizer to create a high-quality query execution plan. Read on to learn how to use statistics and why it’s needed.

Variable Declaration

Understanding SQL Server Query Optimization Statistics

In this article, you will learn what query optimisation statistics are and how SQL Server query optimizer uses statistics. You will also learn how to create and manage statistics, and what are the different ways to determine when statistics were last updated in SQL Server.

The SQL Server Query Optimizer

To understand how to write SQL code for SQL Server that performs well, it is important to appreciate how the query optimizer works. Ben Nevarez explains the essentials, in a broad sweep through a complex subject, in an article taken from his new book 'Inside the SQL Server Query Optimizer'.