See how SQL Server's Parameter Sensitive Plan optimization handles skewed parameters, how to verify dispatcher plans, and where PSP still falls short.
2026-09-04
3,665 reads
Dive deep into the powerful SQL window functions, LAG() and LEAD(). Explore their intricacies, discover real-world examples, and avoid common pitfalls.
2023-12-11
11,871 reads
Over the years, SQL Server Statistics have been discussed in countless blog posts, articles, and presentations, and I believe that they will remain a core topic for a while when speaking about performance. Why is that?
2023-10-04
A query is sometimes super fast and sometimes very slow. One of the main reasons for this problem is Parameter Sniffing. There are several approaches to addressing the Parameter Sniffing issue and this article discusses effective methods for handling Parameter Sniffing in SELECT statements containing a TOP clause.
2023-09-18
This is a short look at a technique that I discovered recently in Management Studio (SSMS). The technique is to compare two graphical execution plans in the tool to understand what they are doing and how two different queries might affect a particular system, both with the image and with the properties' data behind the […]
2023-11-24 (first published: 2021-03-30)
11,305 reads
In this article we look at how to interpret and use the results of STATISTICS IO when tuning SQL Server queries.
2021-02-17
There are plenty of experts that look to teach you about query tuning and the internals of query execution in SQL Server.
2020-07-18
190 reads
In this article we look at different use cases for columnstore indexes like when performing SQL Server count * queries.
2020-01-17
As SQL developers, we tend to think of performance tuning in terms of crafting the best table indices, avoiding scalar and table valued functions, and analyzing query plans (among other things). But sometimes going back to the spec and applying some properties of elementary math can be the best way to begin to improve performance of SQL queries which implement mathematical formulas. This article is a case study of how I used this technique to optimize my SQL implementation of the Inverse Simpson Index.
2021-05-07 (first published: 2019-09-12)
5,525 reads
Introduction Instead of going straight into the topic of the Query Store, I would like to start this Stairway Series by mentioning a few performance tuning scenarios that are very common to production DBAs. I think most of us have been in one of these situations at some time: An application experiencing slowness after a […]
2020-10-07 (first published: 2019-05-13)
7,111 reads
By James Serra
Microsoft shared a broad set of Fabric, Power BI, and SQL updates at FabCon...
By Steve Jones
No, I’m not quitting or retiring. Just going on vacation, but I leave tonight...
Comments posted to this topic are about the item Let's Talk Certifications, which is...
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Comments posted to this topic are about the item The Empty Aggregate
I have this table in a SQL Server 2025 database:
CREATE TABLE [dbo].[CustomerOrder] ( [OrderID] [int] NULL, [CustomerID] [int] NULL, [total] [money] NULL ) ON [PRIMARY] GOWhat is returned from this code? (answers are for the sum and then the count)
SELECT SUM(total) AS sum,
COUNT(total) AS count
FROM dbo.CustomerOrder;
See possible answers