In a recent post I mentioned an approach for working around the import-only nature of Power BI dataflows as a data source in Power BI Desktop, and in an older post I shared information about the enhanced compute engine that’s currently available in preview.
Some recent conversations have led me to believe that I should summarize a few points about dataflows and query folding, because these existing posts don’t make them easy to find and understand.
- When accessing dataflow entities from Power BI Desktop, no query folding takes place, even if the enhanced compute engine is enabled.
- When accessing dataflow entities from other entities in the Power BI service, no query folding takes place unless the enhanced compute engine enabled.
- When accessing dataflow entities from other entities in the Power BI service, query folding will take place when the enhanced compute engine is enabled, because the linked entity’s query will be executed against the cached data in SQL, rather than the underlying CDM folder.
These three statements summarize how query folding works – or does not work – in Power BI dataflows today.
The Power BI team has discussed some of their plans for the enhanced compute engine, so this should change in the future  but as of today, the only dataflows scenario where query folding takes place is when a dataflow is backed by the enhanced compute engine is referenced by a linked entity.
I hope this helps clarify things, at least a little…
 I think this will be around the time the engine goes GA, but I don’t remember for sure, and I’m too lazy to re-watch the MBAS session to double check. If you watch it and let me know, I’ll gladly update this post with the details.