What are two features of a unique secondary key? (Select two)

A unique secondary key serves specific purposes in database systems, particularly in SAP systems using ABAP. One of its primary features is that it is maintained and updated whenever the underlying database table is modified. This allows the unique secondary key to provide correct and accurate access paths for database operations following any changes made to the main data. This ensures data integrity and enables efficient querying based on the secondary key.

The concept is closely related to how database indices work. Whenever a table record is added, deleted, or updated, the unique secondary key needs to reflect these changes. Thus, it ensures that any queries utilizing this key for lookup operations will yield accurate results.

Creating a unique secondary key during the first read access or when the table is filled doesn't apply in the same context. These options suggest moments when the unique secondary key might be instantiated or initialized, but the actual nature of maintaining it focuses on the updates that correspond to table modifications rather than its creation.