How can broken query folding impact refresh time?

< 1 min read

Broken query folding impacts refresh time because transformations are processed in Power BI instead of the database.
In one project, adding a custom column early in Power Query broke folding.
As a result, the entire dataset was loaded before applying filters.
This increased refresh time significantly for large fact tables.
Memory consumption also increased during data load.
The database engine could not use indexes efficiently once folding was broken.
After reordering steps and restoring folding, refresh time improved.
So maintaining query folding is critical for faster and efficient data refresh.

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