Which technique should you use to reduce the size of a Power BI model?

The correct approach to reducing the size of a Power BI model is to set the Storage Mode property to Import. When you use the Import mode, data is loaded into the Power BI model at the point of data import, allowing for efficient storage and improved performance when querying the data. This means that the data resides in-memory, significantly speeding up data retrieval, especially for larger datasets.

Using Import mode allows Power BI to optimize the storage of data internally, which can lead to a smaller overall file size compared to other modes that require continuous data fetching. In contrast, Direct Query, while it may seem to reduce the model size because it does not store data within the Power BI model itself, actually relies on the source database for querying. This can lead to performance issues and may cause limitations, especially for complex calculations or report interactivity.

The options related to setting Query reduction for Filters and Slicers primarily focus on enhancing performance and user experience rather than directly reducing the size of the model itself. These settings help manage how data is retrieved and displayed, but they do not impact the underlying storage of the data within the BI model.