Which SCD type keeps the history of old data by adding a new row?

Which SCD type keeps the history of old data by adding a new row?

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

Answer: (A)

In slowly changing dimensions, preserving history by adding a new row is characteristic of a Type 2 SCD. When a attribute changes, you don’t overwrite the existing record. Instead, you insert a new row with the same business key but a new surrogate key and mark the period during which that row is valid, typically with a start date and an end date (or a current flag). The old row gets its end date set, becoming historical, while the new row represents the current state. This approach lets you query data as of any point in time and see the full history of changes. This contrasts with overwriting data (where history is lost), with a method that stores only the previous value in the same row (Type 3, which handles limited history), or with no changes allowed (Type 0, which keeps data static). Therefore, adding a new row to keep history aligns with Type 2 SCD.

In slowly changing dimensions, preserving history by adding a new row is characteristic of a Type 2 SCD. When a attribute changes, you don’t overwrite the existing record. Instead, you insert a new row with the same business key but a new surrogate key and mark the period during which that row is valid, typically with a start date and an end date (or a current flag). The old row gets its end date set, becoming historical, while the new row represents the current state. This approach lets you query data as of any point in time and see the full history of changes.

This contrasts with overwriting data (where history is lost), with a method that stores only the previous value in the same row (Type 3, which handles limited history), or with no changes allowed (Type 0, which keeps data static). Therefore, adding a new row to keep history aligns with Type 2 SCD.