The Chasm Trap: Missing Relationships

Your chasm trap answer: 'A chasm trap is the inverse. Instead of too many rows, I get too few. An INNER JOIN through a sparse dimension silently drops entities that exist on only one side. Bob has orders but no shipments. The INNER JOIN drops Bob entirely. My total orders metric just lost 70% of its value.' Pair this with the fan trap to show you check for both. The Tell: Words That Signal This Pattern The Scenario the Interviewer Will Draw on the Whiteboard Set up the scenario for the interviewer: 'Orders has alice, bob, carol. Shipments has alice, dave. An INNER JOIN returns only alice. Bob and carol are silently dropped. Dave is silently dropped. Your report shows 1 customer instead of 4.' Walk through it on the whiteboard. The visual makes the problem undeniable. Narrate the impact: 'I