Performance and Tuning

External Article

Index Scans and Table Scans

  • Article

There are several things that you can do to improve performance by throwing more hardware at the problem, but usually the place you get the most benefit from is when you tune your queries. One common problem that exists is the lack of indexes or incorrect indexes and therefore SQL Server has to process more data to find the records that meet the queries criteria. These issues are known as Index Scans and Table Scans.

2025-06-06

Technical Article

Improve Query Performance when SQL Server Ignores Nonclustered Index

  • Article

Do you wonder why SQL Server ignores an index? Do you think about how you can deal with this problem? When you include too many columns in a query you decrease index selectivity. So, if you write a query like “Select * From …” the chance of choosing your nonclustered index will decrease.

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2025-03-03

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The Disabled Index

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Question of the Day

The Disabled Index

I run this code on SQL Server 2022. 

CREATE TABLE Drink
(
    drinkid INT NOT NULL
        CONSTRAINT DrinkPK PRIMARY KEY CLUSTERED,
    drinkname VARCHAR(20),
    rating NUMERIC(2, 1)
)
GO

INSERT INTO Drink
(
    drinkid,
    drinkname,
    rating
)
VALUES
(1, 'Margarita', 4.5),
(2, 'Mojito', 4.3),
(3, 'Old Fashioned', 4.7),
(4, 'Martini', 4.4),
(5, 'Cosmopolitan', 4.2)
GO
ALTER INDEX drinkpk ON dbo.drink DISABLE
GO
SELECT * FROM dbo.Drink
GO
What is the result?

See possible answers