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On-Demand Loading and Direct Lake in Power BI

Chris Webb gives us the beginnings of an origin story:

For any Power BI person, Direct Lake mode is the killer feature of Fabric. Import mode report performance (or near enough) direct on data from the lake, with none of the waiting around for data to refresh! It seems too good to be true. How can it be possible?

The full answer, going into detail about how data from Delta tables is transcoded to Power BI’s in-memory format, is too long for one blog post. But in part it is possible through something that existed before Fabric but which didn’t gain much attention: on-demand loading. 

Click through for another blog post on the topic and an idea of how these tie together.