Question

How can you use Power BI’s query folding feature to push more processing to the source database in complex data preparation scenarios?

How can Power BI’s query folding feature be leveraged to offload data processing tasks to the source database for complex data transformations?

Answer 1

Design For Query Folding: To take advantage of Power BI's query folding feature, queries, and transformations need to be effectively designed so that they can be pushed back to the source database. Query folding translates the different transformations done in Power Query into SQL queries or native language queries, thus reducing the load on Power BI and promoting performance by tapping into the database processing capabilities.

Enable A Query Folding: Using Query-enabled Data Source: Ensure your data source is query-folding compatible. SQL data sources like SQL Server, Oracle, or Azure SQL databases, for example, allow query folding. Transformations happen in Power BI for a data source without query folding.

Transform Using Power Query: When using Power Query, prioritize user transformations that can be folded, such as filtering rows, renaming columns, or joining tables. Never become an obstruction to query folding by introducing unsupported steps like using custom functions on specific complex transformations.

Check Query Folding: Right-click on any step in Power Query Editor and select View Native Query to check if that transformation folds. If not, it doesn't fold, and it exists locally in Power BI.