code: func (d *ddl) getHistoryDDLJob(id int64) (*model.Job, error) {
  	var job *model.Job
  
  	err := kv.RunInNewTxn(d.store, false, func(txn kv.Transaction) error {
  		t := meta.NewMeta(txn)
  		var err1 error
  		job, err1 = t.GetHistoryDDLJob(id)
  		return errors.Trace(err1)
  	})
  
  	return job, errors.Trace(err)
  }
docs: // getHistoryDDLJob gets a DDL job with job's ID from history queue.