Operator of the Week - Lazy Spool

Continuing to illuminate the depths of SQL Server's Query Optimizer, Fabiano shines a light on the sixth major Showplan Operator on his list: the Lazy Spool. What does the Lazy Spool do that's so special, how does the Query Optimizer use it, and why is it so Lazy? Fabiano Amorim explains all.

Controlling Execution Plans with Hints

The Query Optimizer gets it right most of the time, but occasionally it chooses a plan that isn't the best possible. You can give the Query Optimiser a better idea by using Table, Join and Query hints. These come with a risk: Any choices you force on the Optimizer by using hints can turn out to be entirely wrong as the database changes with the addition of data over time. Grant Fritchey, in a chapter from his highly acclaimed book, explains further.

Execution Plans

Analyzing the SQL Server Plan Cache

Keeping in mind the importance of the cache mechanism, how could one get the plans and their usage statistics in SQL Server?

Graphical Execution Plans for Simple SQL Queries

Learning how to read and analyze execution plans takes time and effort. But once you gain some experience, you will find them an essential skill for getting to grips with performance issues in SQL Server Queries. Grant here describes the range of execution plans for different simple SQL Queries.