Power BI offers several connectivity modes that allow you to connect to data sources, and each mode provides different levels of performance, flexibility, and data refresh capabilities. The three primary connectivity modes in Power BI are:
1. Import Mode
Description: In this mode, data from the connected data source is imported into Power BI, and Power BI stores it in a compressed format in memory.
How it works: When you connect to a data source, Power BI fetches the data, processes it, and loads it into its in-memory data model. You can work with this data locally in Power BI Desktop or Power BI Service.
Pros:
High performance due to in-memory processing.
Allows the use of complex calculations, aggregations, and transformations.
Suitable for working with static or periodically updated data.
Cons:
Data must be refreshed periodically (e.g., scheduled refreshes in the Power BI Service).
Size limitations (1 GB limit for Power BI Pro users, larger datasets may require Power BI Premium).
Use Cases:
When performance is critical, and the dataset can fit within the memory limitations.
When you don’t need real-time data, but you want to perform deep analysis and transformations on your data.
2. DirectQuery Mode
Description: In DirectQuery mode, Power BI does not import or store data locally. Instead, it queries the data source in real time whenever a visual or report is loaded or refreshed.
How it works: Power BI sends queries directly to the connected data source, and the source returns the relevant data on-demand. It does not load or cache data in Power BI’s memory.
Pros:
No data size limitations, as data is stored at the source and queried dynamically.
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