Type 2 Slowly Changing Dimension
Type 2 Slowly Changing Dimension (SCD) is a data warehousing technique used to track historical changes in dimension data by creating new records with updated values while preserving old records. It maintains a full history of changes, allowing analysis of data as it existed at any point in time. This is achieved by adding effective date columns, version numbers, or flags to indicate the current and historical records.
Developers should learn Type 2 SCD when building data warehouses or analytical systems that require historical tracking of dimension changes, such as customer address updates, product price changes, or employee role transitions. It enables accurate time-based reporting and trend analysis, supporting business intelligence and compliance needs where audit trails are essential.