The short answer: in the real world, only the first column works. When SQL Server needs data about the second column, it builds its own stats on that column instead (assuming they don’t already exist), and uses those two statistics together – but they’re not really correlated.
2026-04-29
The magic way to get better performance from your system is to write better code from the start.
2026-04-22
175 reads
Monitoring and alerting can be overwhelming tasks, especially for those new to the world of managing production data. One common challenge for any data professional is the identification and management of queries that run for longer than they should.
2026-03-09
In my previous tip, Pagination Performance in SQL Server, I showed how to make SQL pagination more predictable – turning O(n) into O(1). I materialized and cached row numbers to page through instead of calculating them on every request. It wasn’t the whole story, though; real pagination queries rarely get to sort without filtering. Users always want more control, and filtering can threaten that predictability.
2026-02-06
2026-01-30
464 reads
Sometimes we cannot improve query performance because we don’t have control over the code. Consider a query that is generated by Entity Framework (EF) from the application and you do not have access to the source code. The main question is how you can improve SQL Server query optimization for a poorly performing query?
2026-01-05
First off, I understand if you read the headline and you have a knee-jerk reaction. I totally understand that there are a lot of people out there who hate AI, and believe me, I hate most uses of it. Lots of its advice can be misleading at best, and absolute garbage at worst.
2025-12-22
Batched deletions are a common strategy in SQL Server to manage large datasets without overloading the system, but poorly tuned deletes can cause blocking, long-running transactions, and heavy log usage. Learn how to monitor and optimize these processes for smooth, efficient database performance.
2025-12-12
Learn about filtered indexes in SQL Server, how they work, and how they can help improve performance.
2025-11-24
5,256 reads
Learn how indexes can help you with more than just querying data.
2025-10-22
18,325 reads
By James Serra
Making Data AI-Ready, Part 1 (This is the first article in a three-part series...
By Steve Jones
Thanks for attending my sessions. Resources below: Slides: Using Data API Builder GitHub repo: ...
By Steve Jones
Thanks to everyone that attended my sessions at VS Live San Diego yesterday. It...
When I run my query from DW, which uses a linked server, it times...
Comments posted to this topic are about the item Implementing Type 4 Slowly Changing...
Comments posted to this topic are about the item 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