pbiplintRules / DAX Expressions
Use the TREATAS function instead of INTERSECT for virtual relationships
What it checks
Measures and calculation items that call INTERSECT.
Why it matters
INTERSECT is used to push a filter from one table to another when no relationship exists: take the values on one side and intersect them with the other. TREATAS does the same job by treating the first table's values as a filter on the second table's columns, and the engine applies it as a filter, which is much cheaper than materializing both sets and intersecting them.
How to fix it
Replace CALCULATE([Measure], INTERSECT(VALUES(Table2[Key]), VALUES(Table1[Key]))) with CALCULATE([Measure], TREATAS(VALUES(Table1[Key]), Table2[Key])). The SQLBI article in the links covers the pattern.
Quirks
- INTERSECT used for anything other than a virtual relationship, such as set logic inside a measure, is flagged too.