Which SCD type is least suitable when the data model is expected to evolve with new attributes?

Which SCD type is least suitable when the data model is expected to evolve with new attributes?

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

Answer: (C)

When a data model is expected to grow with new attributes, how history is stored matters. Type 2 keeps full history by creating a new row for every change, identified by a surrogate key. If you add new attributes to the model, you’ll need to alter the dimension schema and then backfill or extend every historical row to include these new attributes. This leads to more schema changes, larger history tables, and more complex queries to reconstruct current versus historical states. That heavy maintenance makes it the least suitable choice for an evolving attribute set. Other approaches either avoid maintaining history across many attributes, store only limited history, or separate history from the current state to accommodate schema evolution more gracefully.

When a data model is expected to grow with new attributes, how history is stored matters. Type 2 keeps full history by creating a new row for every change, identified by a surrogate key. If you add new attributes to the model, you’ll need to alter the dimension schema and then backfill or extend every historical row to include these new attributes. This leads to more schema changes, larger history tables, and more complex queries to reconstruct current versus historical states. That heavy maintenance makes it the least suitable choice for an evolving attribute set. Other approaches either avoid maintaining history across many attributes, store only limited history, or separate history from the current state to accommodate schema evolution more gracefully.