Slowly changing dimension.
also: slowly changing dimensions · SCD · SCD Type 2 · SCD type 2How a dimension keeps history when attributes change; Type 2 adds a new row per change with valid_from, valid_to and is_current.
the two-minute refresher
- Type 0: never change. Type 1: overwrite (no history).
- Type 2 (most common): a new row per change, so point-in-time reports stay correct.
- Type 3: current and previous value columns, one level of history.
- Type 6: a 1 + 2 + 3 hybrid.