Cardinality Estimation for a Predicate on a COUNT Expression
Paul White takes you on an optimizer journey, exploring how SQL Server comes up with cardinality estimates for COUNT queries.
2017-05-17
3,222 reads
Cardinality Estimates
Bad Cardinality Estimates from SSMS Plans – Redux
Aaron Bertrand shares some insight about early changes to Plan Explorer that help to provide you with the most accurate information we can.
2016-04-04
2,780 reads
Fixing Gatekeeper Row Cardinality Estimate Issues
The Query Optimiser needs a good estimate of the number of rows likely to be returned by each physical operator in order to select the best query plan from the most likely alternatives. Sometimes these estimates can go so wildly wrong as to result in a very slow query. Joe Sack shows how it can happen with SQL Queries on a data warehouse with a star schema.
2012-12-10
1,163 reads
Blogs
A New Word: Dolorblindness
By Steve Jones
dolorblindness – n. the frustration that you’ll never be able to understand another person’s...
Claude Code Helps Analyze Test Data Manager Log Files
By Steve Jones
I had a customer ask about analyzing their Test Data Manager (TDM) usage to...
PowerPoint to HTML with Claude AI
By Steve Jones
I had an idea for an animated view of a sales tool, and started...
Forums
Optimism Without Illusion or Why AI Needs Blunt Technologists
Comments posted to this topic are about the item Optimism Without Illusion or Why...
SSIS with VS2022 64/32 issue with Excel files
Hi all, I'm trying to do classic scenario for loading multiple Excel files into...
Case part is sloooooow
Hi So the case statement is slowing this down - but for the life...
Question of the Day
The String Distance I
In SQL Server 2025, what is returned by this code:
SELECT EDIT_DISTANCE('tim', 'tom')
Assume preview features are enabled. See possible answers