Composite models in Power BI Desktop

Composite models in Power BI Desktop

Previously in Power BI Desktop, when we used a DirectQuery in a report, no other data connections - whether DirectQuery or Import - were allowed for that report. With composite models, that restriction is removed. A report can seamlessly include data connections from more than one DirectQuery or Import data connection, in any combination you choose.

Below are the three related features in Composite models:

• Composite models: Allows a report to have multiple data connections, including DirectQuery connections or Import, in any combination. 
• Many-to-many relationships: With composite models, you can establish many-to-many relationships between tables. This approach removes requirements for unique values in tables. It also removes previous workarounds, such as introducing new tables only to establish relationships.
• Storage mode: You can now specify which visuals require a query to back-end data sources. Visuals that don't require a query are imported even if they're based on DirectQuery. This feature helps improve performance and reduce back-end load. Previously, even simple visuals such as slicers initiated queries that were sent to back-end sources.

Set the storage mode

Each table in a composite model has a storage mode that indicates whether the table is based on DirectQuery or Import. The storage mode can be viewed and modified in the Property pane. 

To display the storage mode, right-click a table in the Fields list, and then select Properties. The following image shows the storage mode for the SalesTargets table.

The storage mode can also be viewed on the tooltip for each table.

For any Power BI Desktop file (a .pbix file) that contains some tables from DirectQuery and some Import tables, the status bar displays a storage mode called Mixed. You can click that term in the status bar and easily switch all tables to Import.