TIL: Slowly Changing Dimensions (SCD) in Data Warehousing

Slowly Changing Dimensions (SCD) is a method for handling changes in dimension tables in a data warehouse. SCD Type 1 involves overwriting old data with new data, losing historical records. This approach is simple and storage-efficient but lacks history tracking. SCD Type 2 keeps historical records by inserting new rows for each change, marking old records as inactive. This approach provides full historical tracking but causes tables to grow over time. SCD Type 3 stores limited history in additional columns, saving space compared to Type 2 but unable to track multiple historical changes. The choice of SCD type depends on business needs, with Type 1 suitable when history isn't needed, Type 2 for full history, and Type 3 for limited history. SCDs ensure data integrity while keeping track of changes. It's essential to determine whether historical records are necessary to guide the approach. By choosing the right SCD type, businesses can effectively manage changes in their customer database.