code: func (m *Meta) UpdateDDLReorgStartHandle(job *model.Job, startHandle int64) error {
  	err := m.txn.HSet(mDDLJobReorgKey, m.reorgJobStartHandle(job.ID), []byte(strconv.FormatInt(startHandle, 10)))
  	return errors.Trace(err)
  }
docs: // UpdateDDLReorgStartHandle saves the job reorganization latest processed start handle for later resuming.