What is required for a marketer to update a data extension nightly based on received data files from SFTP?

To update a data extension nightly using received data files from SFTP, having a Primary Key is essential. The Primary Key acts as a unique identifier for each record within the data extension. This allows the system to distinguish individual records and determine whether to update an existing record or insert a new one when processing the incoming data files.

By having a defined Primary Key, you ensure that each record is uniquely identifiable, which is critical when handling updates from external sources like SFTP. This means that if there are changes to existing records in the data being imported, the system can accurately modify them based on the Primary Key, rather than duplicating records or losing data integrity.

In contrast, while the Subscriber Key is important for identifying subscribers within Marketing Cloud, it does not play a role in the data extension update process unless it serves as the Primary Key. Multiple Primary Keys may imply a composite key scenario, which complicates the update process without necessarily providing a unique identification framework for simple updates. Send Relationships, while relevant for linking data extensions for email sends, do not influence the update process directly in relation to Nightly updates from SFTP files.