Which type is described as 'the history is preserved by adding new rows'?

Which type is described as 'the history is preserved by adding new rows'?

• A. Type 0 SCD
• B. Type 1 SCD
• C. Type 2 SCD
• D. Type 4 SCD

Answer: (C)

Preserving history by adding new rows is the hallmark of Slowly Changing Dimension Type 2. In this approach, when an attribute changes, a new row is inserted with its own surrogate key and a validity window (such as start and end dates) while the old row remains but is marked as no longer current. This keeps every version of the record, enabling complete historical analysis over time. By contrast, Type 1 overwrites the existing row and loses history, Type 3 stores only a limited prior value in the same row, and Type 4 uses a separate history structure.

Preserving history by adding new rows is the hallmark of Slowly Changing Dimension Type 2. In this approach, when an attribute changes, a new row is inserted with its own surrogate key and a validity window (such as start and end dates) while the old row remains but is marked as no longer current. This keeps every version of the record, enabling complete historical analysis over time. By contrast, Type 1 overwrites the existing row and loses history, Type 3 stores only a limited prior value in the same row, and Type 4 uses a separate history structure.