Summary

In this chapter, we saw how the different storage modes in Power BI work. Import mode datasets create an in-memory data cache in the Power BI service. DirectQuery mode datasets pass queries to the external data sources. Delta Lake allows connections to Delta Table structures in a Fabric lakehouse or warehouse. Generally, import mode is the fastest because it is local to Power BI, in-memory, a column-based analytical database, and compresses data. However, DirectQuery mode provides a way to always have the latest data returned from the source and avoid managing refreshes. Fabric’s Direct Lake is somewhere in between. There is a trade-off between all three options. There is also the composite model if the data is large, but you can provide some aggregate tables in import mode.

You also learned about the role of on-premises gateways for enterprises to allow Power BI to connect securely with on-premises data sources. Gateways host Power BI’s mashup engine, where...