code: def touch(self, connection=None):
          
          self.create_marker_table()
  
          if connection is None:
              connection = self.connect()
  
          connection.execute_non_query(
              """IF NOT EXISTS(SELECT 1
                              FROM {marker_table}
                              WHERE update_id = %(update_id)s)
                      INSERT INTO {marker_table} (update_id, target_table)
                          VALUES (%(update_id)s, %(table)s)
                  ELSE
                      UPDATE t
                      SET target_table = %(table)s
                          , inserted = GETDATE()
                      FROM {marker_table} t
                      WHERE update_id = %(update_id)s
                """.format(marker_table=self.marker_table),
              {"update_id": self.update_id, "table": self.table})
  
          # make sure update is properly marked
          assert self.exists(connection)
docs: Mark this update as complete.
  
          IMPORTANT, If the marker table doesn't exist,
          the connection transaction will be aborted and the connection reset.
          Then the marker table will be created.