Technical Article

Understanding and Controlling Parallel Query Processing in SQL Server

Data warehousing and general reporting applications tend to be CPU intensive because they need to read and process a large number of rows. To facilitate quick data processing for queries that touch a large amount of data, Microsoft SQL Server exploits the power of multiple logical processors to provide parallel query processing operations such as parallel scans. Through extensive testing, we have learned that, for most large queries that are executed in a parallel fashion, SQL Server can deliver linear or nearly linear response time speedup as the number of logical processors increases. However, some queries in high parallelism scenarios perform suboptimally. There are also some parallelism issues that can occur in a multi-user parallel query workload. This white paper describes parallel performance problems you might encounter when you run such queries and workloads, and it explains why these issues occur. In addition, it presents how data warehouse developers can detect these issues, and how they can work around them or mitigate them.

Blogs

Don’t Miss Out – SQL Server 2025 Unleashed Training Starts Next Monday!

By

Next Monday, March 9, 2026, my one-day live online training SQL Server 2025 Unleashed:...

What is ALM in Fabric?

By

As someone who’s worked with data for over 20 years and with many cloud...

The Most Successful Startups in 2025 — And What They Have in Common

By

2025 belongs to the AI startups. If you peek into the tech headlines, you’ll...

Read the latest Blogs

Forums

A Quick Restore

By Steve Jones - SSC Editor

Comments posted to this topic are about the item A Quick Restore

Guarding Against SQL Injection at the Database Layer (SQL Server)

By tedo

Comments posted to this topic are about the item Guarding Against SQL Injection at...

Ola Hallengren Index Optimize Maintenance can we have data compression = page

By JSB_89

I have a quick question on Ola Hallengren Index Optimize Maintenance . Do we...

Visit the forum

Question of the Day

A Quick Restore

While doing some testing of an application, I wanted to reset my environment after doing some testing with this code:

USE DNRTest

BACKUP DATABASE DNRTest TO DISK = 'dnrtest.bak'
GO
/*
Bunch of stuff tested here
*/RESTORE DATABASE DNRTest FROM DISK = 'dnrtest.bak' WITH REPLACE
What happens if this runs, assuming the "bunch of stuff" isn't anything affecting the instance.

See possible answers