Hybrid SCD and Type 6

Type 6 appears in senior interviews at companies dealing with customer segmentation or geographic reorganizations. The interviewer tests whether you know it exists, when it is justified, and what it costs. Saying 'I have never heard of Type 6' is not disqualifying, but knowing it and being able to articulate the write-amplification tradeoff is a clear differentiator. The Trigger: When the Interviewer Describes This Scenario Your Type 6 answer: 'I need Type 6 when the dashboard shows both historical AND current values on the same row: customer was in Gold tier at time of purchase, is now in Platinum. With pure Type 2, getting the current tier requires a self-join. Type 6 puts both values on every row by overwriting a current_ column across all historical rows.' Name the self-join problem. T