Connect to a data source
With Power BI Workspace Collections, you can embed reports into your own app. When you embed a Power BI report into your app, the report connects to the underlying data by importing a copy of the data or by connecting directly to the data source using DirectQuery.
Power BI Workspace Collections is deprecated and is available until June 2018 or when your contract indicates. You are encouraged to plan your migration to Power BI Embedded to avoid interruption in your application. For information on how to migrate your data to Power BI Embedded, see How to migrate Power BI Workspace Collections content to Power BI Embedded.
Here are the differences between using Import and DirectQuery.
|Tables, columns, and data are imported or copied into the report's dataset. To see changes that occurred to the underlying data, you must refresh, or import, a complete, current dataset again.||Only tables and columns are imported or copied into the report's dataset. You always view the most current data.|
With Power BI Workspace COllections, you can use DirectQuery with cloud data sources but not on-premises data sources at this time.
The On-Premises Data Gateway is not supported with Power BI Workspace Collections at this time. This means you cannot use DirectQuery with on-premises data sources.
Supported data sources
- Azure SQL database
- Azure SQL Data Warehouse
You can import using all of the available data sources within Power BI Desktop. You will not be able to refresh that data within Power BI Workspace Collections. You have to upload changes to your PBIX file to Power BI Workspace Collections. This is due to no available gateway.
Benefits of using DirectQuery
There are two primary benefits when using DirectQuery:
- DirectQuery lets you build visualizations over large datasets, where it otherwise would be unfeasible to first import all of the data.
- Underlying data changes can require a refresh of data, and for some reports, the need to display current data can require large data transfers, making reimporting data unfeasible. By contrast, DirectQuery reports always use current data.
Limitations of DirectQuery
There are a few limitations to using DirectQuery:
- All tables must come from a single database.
- If the query is overly complex, an error occurs. To remedy the error you must refactor the query so it is less complex. If the query must be complex, you need to import the data instead of using DirectQuery.
- Relationship filtering is limited to a single direction, rather than both directions.
- You cannot change the data type of a column.
- By default, limitations are placed on DAX expressions allowed in measures. See DirectQuery and measures.
DirectQuery and measures
To ensure queries sent to the underlying data source have acceptable performance, limitations are imposed on measures. When using Power BI Desktop, advanced users can choose to bypass this limitation by choosing File > Options and settings > Options. In the Options dialog, choose DirectQuery, and select the option Allow unrestricted measures in DirectQuery mode. When that option is selected, any DAX expression that is valid for a measure can be used. Users must be aware; however, that some expressions that perform well when the data is imported may result in slow queries to the backend source when in DirectQuery mode.
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