Time for a new video blog. This time, the topic is bad parameter sniffing. And with 43 minutes, the video is a bit longer than what I normally shoot for.
What is it? What can you do about it?
The video starts with an explanation of two good features: parameter sniffing and plan caching. But those features can interact in an unwanted way, resulting in erratic bad performance. Now we have what I call “bad parameter sniffing”.
Starting at approximately 8:30, I then describe the three most common root causes for bad parameter sniffing: equality filters on a column with a skewed data distribution; inequality filters with varying selectivity; and optional parameters.
Than, at approximately 16:30, I talk about how you can recognize bad parameter sniffing in your databases, and how the Query Store has made it a lot easier to troubleshoot this issue.
The most important is of course: what can you do about it? That takes up the largest part of the video, from 21:00 until the end of the video.
More of me?
Was this useful to you? Do you want to learn more from me?
You can click here to see an overview of my scheduled conference talks. If you attend one of those, you get a lot of other presenters and sessions thrown in as well!
To learn really everything about SQL Server execution plans, check out my video training. Over 20 hours of super high quality video content (and more will be added when ready).
Or you can hire me to fix the performance problems (and perhaps some security issues too?) on your server, or for in house training.
