Query folding in Power Query
summary
Explains that query folding pushes Power Query transforms into the source for much better refresh performance and shows how to verify it: Power BI Desktop + SQL Server Profiler captures the generated SELECT with WHERE for a column removal and a day-name filter, while Power Query Diagnostics (and Fiddler) reveal OData calls. Demonstrates that adding an index column stops folding, that rewriting steps (custom column = 1 for a Cartesian join, reordering, or using value.nativequery enable folding=true) can restore folding, and that table.stopfolding forcibly prevents it; also shows view native query and query diagnostics.
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chapters (10)
- 0:00Introduction to query folding
- 1:11What is query folding
- 3:53Importance of query folding
- 5:42Detecting query folding
- 10:28Using view native query
- 11:41Diagnosing query folding
- 14:43Folding in Power Query Online
- 15:51When folding stops
- 17:17Optimizing folding techniques
- 19:24Native SQL and conclusions
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