The Dangerous Truth About Scalar Functions in 45 Seconds, The "45 Seconds DBA Series" | Part 20
Before we dive into today's topic, if you missed my previous post you can take a look at SSMS 22.6.0 Is OUT! Review & Test! . ๐ If you found this deep-dive helpful, feel free to check out the ads—your support helps me keep creating high-quality SQL Server content for the community. The Dangerous Truth About Scalar Functions in 45 Seconds The "45 Seconds DBA Series" | Part 20 Scalar UDFs are the silent killers of SQL Server performance. In this post, I will reveal why they hide their true cost and how they turn a fast query into a row-by-row disaster. ๐ง TL;DR ✔️ Scalar UDFs force RBAR (Row-By-Agonizing-Row) execution, bypassing the set-based power of the optimizer. ๐ฃ ✔️ Inhibits Parallelism: Traditional scalar functions force your entire query to run on a single thread. ๐งต ✔️ Hidden Costs: Execution plans ofte...