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
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Forums
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Question of the Day
Missing the Jaro Winkler Distance
I upgraded a SQL Server 2019 instance to SQL Server 2025. I wanted to test the fuzzy string search functions. I run this code:
SELECT JARO_WINKLER_DISTANCE('tim', 'tom')
I get this error message:Msg 195, Level 15, State 10, Line 1 'JARO_WINKLER_DISTANCE' is not a recognized built-in function name.What is wrong? See possible answers