Type 2 slowly changing dimension (SCD) describes which concept?

Type 2 slowly changing dimension (SCD) describes which concept?

• A. Type 1 slowly changing dimension
• B. Type 2 slowly changing dimension (SCD)
• C. Columnar store indexing
• D. Data lineage tracking

Answer: (B)

It describes how a Type 2 slowly changing dimension preserves history of dimension attributes. When a dimension value changes, a new row is inserted with the updated data and a new surrogate key, while the previous row is kept but marked as not current (often with an end date or a current flag). This approach maintains a full history, enabling you to query the dimension as it existed at any point in time and perform time-based analyses. It differs from Type 1, which would overwrite the old value and lose historical data. Columnar store indexing is about storage layout and performance, not how dimension changes are tracked, and data lineage tracking focuses on tracing data provenance through transforms rather than maintaining versioned dimension records.

It describes how a Type 2 slowly changing dimension preserves history of dimension attributes. When a dimension value changes, a new row is inserted with the updated data and a new surrogate key, while the previous row is kept but marked as not current (often with an end date or a current flag). This approach maintains a full history, enabling you to query the dimension as it existed at any point in time and perform time-based analyses. It differs from Type 1, which would overwrite the old value and lose historical data. Columnar store indexing is about storage layout and performance, not how dimension changes are tracked, and data lineage tracking focuses on tracing data provenance through transforms rather than maintaining versioned dimension records.