History requirements need to be addressed when designing reporting systems. If Bob our Customer moves five times in the last year for example, we can choose to capture only the most current information where Bob lives today, which is known as a Type 1 Slowly Changing Dimension (SCD). Or we can store all history and therefore all of Bob’s address changes, which is known as a Type 2 SCD. Or we can store some history such as Bob’s original or previous address, which is known as a Type 3 SCD. Type 3 is frequently chosen for purely technology reasons such as to simplify development, save storage space, or increase query performance. Is the decision to store some history (Type 3) over all history (Type 2) ever driven by business needs, or is it always dictated purely by technology? In other words, what business reasons (if any) are there for modeling a Type 3?
SCD Type 3 for me?