Factless Facts and Coverage Tables

Factless facts are the interview curveball. A fact table with no measures. It records that a relationship existed, not that a measurable event occurred. Most candidates have never encountered one, and it trips them up because it violates the assumption that fact tables contain numbers. The Tell: Words That Signal This Pattern Two Types of Factless Facts The Power Query: What Did NOT Happen Your factless fact answer: 'The coverage fact lets me answer what did NOT happen. Products on promotion that had zero sales. Students enrolled in a course who never attended. Without the coverage fact, I would need a massive CROSS JOIN to generate all possible combinations. The factless fact pre-computes the eligible set.' Say 'what did NOT happen.' That is the phrase that signals you understand this pat