Execution Plans

SQL Server execution-plans-3 book cover

Free eBook: SQL Server Execution Plans, Third Edition

  • Article

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.

2020-12-23 (first published: )

119,575 reads

Technical Article

Changes to SQL Server 2012 Execution Plans

  • Article

I’ve been working with execution plans quite a lot in SQL Server 2012. There are a number of changes, most of them associated with new or different functionality. I had not noticed anything really fundamental until recently. I’ve become a huge proponent of always checking the properties of the SELECT statement. There’s so much useful information in there about what’s happened with the plan generation in the optimizer (not low level stuff, but the big picture items) that you should always be checking it first as a fundamental part of your plan examinations.

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2011-12-14

6,689 reads

Technical Article

Free ebook: SQL Server Execution Plans

  • Article

This free book is brought to you by Red Gate Software and Simple Talk Publishing. Why my query is running slow? Why isn't my index getting used? In order to answer these questions, you have to ask the same return question in each case: have you looked at the execution plan? Grant Fritchey provides the only dedicated and detailed guide to this essential topic.

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2011-07-11

6,178 reads

External Article

Operator of the Week - Lazy Spool

  • Article

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.

2010-06-28

2,774 reads

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Question of the Day

A Strange Choice

What is returned when I run this code in SQL Server 2022?

CREATE TABLE CatIndex
( indexval VARCHAR(20)
)
GO
INSERT dbo.CatIndex (indexval) VALUES ('1'), ('2'), ('3')
GO
SELECT CHOOSE(indexval, cast('2025-01-01' AS DATE), CAST('2025-02-01' AS DATE), CAST('2025-03-01' AS DATE))
FROM dbo.CatIndex AS ci

See possible answers