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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Question of the Day

How Long is a Long I/O?

In SQL Server 2025, a long I/O is recorded in the error log with message 833. How long much an I/O request be outstanding before this message is written to the log?

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