What is data blending? When do you use this?

Blending combines data from separate sources by aggregating each one to the level of the view and then matching the results on a shared dimension.

Use it when the sources genuinely cannot be joined — different databases with no cross-database connection, or a managed API alongside a warehouse table.

It is also the better answer when the two sides have different granularity. Daily transactions against monthly targets will fan out badly in a join, duplicating the target across every day. Blending aggregates each side first, so the numbers stay correct.

Where both tables live in the same source, join instead. A join is one query rather than two, gives you row-level access to both sides, and can be published as a single data source.