def METHOD_NAME(self):
    if self.mapping.action == DataOperationType.ETL_UPSERT:
        # We've retrieved IDs from the org, so include them.
        # If we treat "Id" as an "external_id_name" then it's
        # allowed to be sparse.
        tablename = upsert_tablename_for_obj_and_keys(
            self.mapping.sf_object, self.mapping.update_key
        )
        table = self.metadata.tables[tablename]
        id_column = table.columns["Id"]
        return [id_column]