Skip to main content
cancel
Showing results for 
Search instead for 
Did you mean: 

Join us for an expert-led overview of the tools and concepts you'll need to become a Certified Power BI Data Analyst and pass exam PL-300. Register now.

Reply
cuongle
Advocate II
Advocate II

How Power BI direct query optimise SQL

I am not sure that I understand how Power BI direct query works under the hood and whether Power BI optimise the query or not. Assume I have a filter (slicer with single selection) binding on column ColumnX in order to filter data on table: TableY

 

When user select value on slicer, does Power BI optimise query like:

 

SELECT * FROM TABLE tableY

WHERE ColumnX = 'Value'

 

Or, Power BI get all data from TableY and then filter happens in memory

 

 

1 ACCEPTED SOLUTION
Eric_Zhang
Microsoft Employee
Microsoft Employee

@cuongle

For SQL Server, I've captured what Power BI does in direct query when selecting the slicer, with the help of SQL Server profiler. Power BI actually sends a query with where filter as you mentioned, instead of get all data and filter in memory, though the query is usually not efficient.  So I think the similar behavior is applied when connecting to other databases and it can be easily proved with individual profiler tools.

 

 

View solution in original post

1 REPLY 1
Eric_Zhang
Microsoft Employee
Microsoft Employee

@cuongle

For SQL Server, I've captured what Power BI does in direct query when selecting the slicer, with the help of SQL Server profiler. Power BI actually sends a query with where filter as you mentioned, instead of get all data and filter in memory, though the query is usually not efficient.  So I think the similar behavior is applied when connecting to other databases and it can be easily proved with individual profiler tools.

 

 

Helpful resources

Announcements
Join our Fabric User Panel

Join our Fabric User Panel

This is your chance to engage directly with the engineering team behind Fabric and Power BI. Share your experiences and shape the future.

June 2025 community update carousel

Fabric Community Update - June 2025

Find out what's new and trending in the Fabric community.