CustomerMaster is described as a Type 2 slowly changing dimension. Which statement best describes this concept?

CustomerMaster is described as a Type 2 slowly changing dimension. Which statement best describes this concept?

• A. Type 1
• B. Type 2
• C. Type 3
• D. Type 0

Answer: (B)

Type 2 slowly changing dimension preserves a complete history of changes by adding a new record instead of overwriting the existing one. When a customer’s information changes, a new row is inserted with the updated details, a new surrogate key, and a new effective period (for example start date to end date). The old row is kept but marked as no longer current, typically with an end date or a current flag. This approach lets you answer questions like “What did the customer’s address look like on a given date?” or “How did a customer’s status evolve over time?” while still keeping the current view up to date. It contrasts with Type 1, which overwrites data and loses history; Type 3, which stores limited, last-known history in extra columns; and Type 0, which doesn’t allow changes at all. For CustomerMaster, maintaining a full history of changes is the defining trait of a Type 2 SCD.

Type 2 slowly changing dimension preserves a complete history of changes by adding a new record instead of overwriting the existing one. When a customer’s information changes, a new row is inserted with the updated details, a new surrogate key, and a new effective period (for example start date to end date). The old row is kept but marked as no longer current, typically with an end date or a current flag. This approach lets you answer questions like “What did the customer’s address look like on a given date?” or “How did a customer’s status evolve over time?” while still keeping the current view up to date. It contrasts with Type 1, which overwrites data and loses history; Type 3, which stores limited, last-known history in extra columns; and Type 0, which doesn’t allow changes at all. For CustomerMaster, maintaining a full history of changes is the defining trait of a Type 2 SCD.