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
Reverse Engineering a Physical Model Diagram
By Steve Jones
I recently wrote about a logical diagram with Redgate Data Modeler. That was interesting,...
Prepping for Certification, Part 3 of ?
By Brian Kelley
After I have understood the details for a certification test (part 1), including format...
SQL Training Black Friday Deals
By Brian Kelley
If you're looking for particular "Black Friday" deals, here is what I've seen advertised...
Forums
Best analysis approach to reduce data type length in multiple tables
Hello SSC, I hope everyone is having a happy and safe holiday season! I...
Do you separate data/log files and TempDB files on different disks using AWS EC2
Hello, I am receiving multiple direction on deploying SQL Servers in AWS EC2. ...
Service account being in local admin in AWS EC2 environment?
Hello, I am working with a company on their database administration. I am trying...
Question of the Day
A New Operator
In SQL Server 2025, what does this code return?
SELECT '1' || '0'See possible answers