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

SQLServerCentral Article

The Paradox of NOLOCK: How Dirty Reads Can Sometimes Be Cleaner

  • Article

Every SQL Server developer has heard it: "Don't use NOLOCK in production!" But this common rule isn't as simple as it seems. Sometimes, what seems like a bad practice can actually be the right choice. Let's explain what NOLOCK really does in simple terms. When you use NOLOCK, you're telling SQL Server "just show me […]

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2024-12-09

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Question of the Day

Using OPENJSON

I have some data in a table that looks like this: 

BeerID BeerName    brewer               beerdescription
1      Becks       Interbrew            Beck's is a German-style pilsner beer 
2      Fat Tire    New Belgium          Toasty malt, gentle sweetness, flash of fresh hop bitterness.
3      Mac n Jacks Mac & Jack's Brewery This beer erupts with a floral, hoppy taste
4      Alaskan Amber Alaskan Brewing     Alaskan Brewing Amber Ale is an "alt" style beer
8      Kirin       Kirin Brewing         Kirin Ichiban is a Lager-type beer
If I run this, what is returned? 
select t1.[key]
    from openjson((select t.* FROM Beer AS t for json path)) t1

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