What action is required when the natural key already exists in the dimension table while updating a Type 1 SCD?

When updating a Type 1 Slowly Changing Dimension (SCD), the action that needs to be taken when the natural key already exists in the dimension table is to overwrite the existing record. In a Type 1 SCD, the focus is on maintaining the most current data without preserving historical changes. Therefore, if a record with a matching natural key is found, the existing attributes of that record are replaced with the new values provided in the update. This allows for the latest information to be reflected in the dimension table without retaining any previous versions of the data.

The nature of Type 1 SCDs emphasizes a straightforward update mechanism, ensuring that users always see the current state of data, which simplifies querying and reporting tasks. This characteristic distinguishes it from Type 2 or Type 3 SCDs, where historical data or previous versions might be retained for audit or analysis purposes.