Fundamentals of Parameter Sniffing
Sometimes a query just goes slow for no apparent reason.
Fundamentals
What you will get:
- Watch on any Device
- 4 sections
- lectures
- of video
Last updated: 30 June 2022
Your Instructor
I make Microsoft SQL Server go faster. I've been working with SQL Server since the late 1990s, and I'm one of the rare Microsoft Certified Masters of SQL Server. I love teaching, travel, and laughing. I live in Las Vegas, Nevada.
Course Description
Sometimes the exact same query goes slow out of nowhere.
Your current fix is to update statistics, rebuild indexes, or restart SQL Server. It works, but you don’t know why.
You’re facing a problem called parameter sniffing: SQL Server “sniffs” the first set of parameters for a query, builds an execution plan for it, and then reuses that same plan no matter what parameters get called. It’s been the bane of our performance tuning for decades, and it doesn’t appear to be going away anytime soon – in fact, in SQL Server 2019, it even gets worse!
In this one-day class, you’ll follow along with me in the Stack Overflow database on your own laptop or desktop as you learn:
- * What kinds of queries are vulnerable to parameter sniffing
- * How to test your code to see if it’s vulnerable
- * Why tactics like rebuilding indexes and updating statistics fix one query, but make others worse
- * How to proactively patrol your server to uncover the problems before they bring you down
This course is 100% demos: the only slides are the introductions at the start of the day, and the recap at the end of the day. The rest of the time, we’ll be working in SQL Server Management Studio. Roll up your sleeves and join me!
Want to save a bundle? This class is included in my Recorded Class Season Pass: Fundamentals bundle.