What is a disadvantage of Type 2 slowly changing dimension?

• A. Data warehouse size is reduced
• B. Adding new records can be costly operation and is not recommended when attributes or columns might be added in the future
• C. Historical data is overwritten
• D. It eliminates the need for history

Answer: (B)

Type 2 slowly changing dimension preserves history by creating a new row each time a dimension attribute changes, with dates indicating when that row is valid. The key downside is that the table grows with every change, so storage needs increase and ETL and query performance become more complex and heavier. If you expect to add new attributes later, this approach is less flexible because you’d need to alter the schema to add columns and then manage how those new attributes apply to historical rows, which can be costly and error-prone. The other statements don’t fit because Type 2 does not reduce size, does preserve history rather than overwriting it, and does not eliminate the need to track historical data.