Forum Discussion
Cardinality Estimator understading
I have a query that i am running from the query analyser, there are no trace flags enabled in it. When do properties of the select in the query plan I see following
My database is at compatibility lever 150, so why i am seeing this? Is it normal ?
The cardinality estimation version can vary, and a lower value doesn't automatically imply something is wrong.
Read the following article thoroughly as it covers:
- Some of the scenarios where the cardinality estimation can run into issues (probably the most useful part to read);
- How to monitor cardinality and make sense of the results;
- How to force cardinality (where appropriate to do so.)
Cheers,
Lain
LainRobertson Thanks for your help. I have gone through the article.
The query i am looking at is performing poorly and i am not sure why it is using an old cardinality estimator even though my database is at latest CE.
The article outlines multiple reasons in the second bullet point list near the top of the article.
Cheers,
Lain
