What is query folding in Power BI?

< 1 min read

Query folding means Power BI pushes data transformation steps back to the source database.
Instead of processing in Power BI, the database performs filtering, joins, and aggregations.
In my project, filtering last 2 years sales was executed in SQL Server, not locally.
This reduced dataset size and improved refresh performance.
We checked folding using “View Native Query” option in Power Query.
Certain steps like custom columns or index columns stopped folding.
So we reordered transformations to keep filters and joins early.
This reduced refresh time from 25 minutes to 6 minutes.
Works best with structured sources like SQL Server or Oracle.
Important for large datasets and scheduled refresh optimization.

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