Question 220
A performance review finds a many-to-many relationship where a conformed dimension could be used. What redesign may help?
Explanation
Correct Answer
Introduce a unique conformed lookup dimension instead of a repeated-key direct link. Clear one-to-many relationships usually improve predictability in a star model.
Incorrect Answers
That recommendation applies when a Date slicer unexpectedly filters orders through ShipDate rather than OrderDate. This solves “unexpectedly filters orders through ShipDate rather than OrderDate”; the stated issue is “relationship where a conformed dimension could be used”.
A lookup's grain must be one record per relationship key. The deciding difference is “lookup has duplicates so the relationship auto-detects many-to-many” versus “relationship where a conformed dimension could be used”.
Ambiguous paths can create incorrect or prohibited model filtering. That is a different operating condition from “relationship where a conformed dimension could be used”: “between Region and Sales and gets ambiguity errors”.