code: func (e *ChecksumTableExec) Next(ctx context.Context, req *chunk.RecordBatch) error {
  	req.Reset()
  	if e.done {
  		return nil
  	}
  	for _, t := range e.tables {
  		req.AppendString(0, t.DBInfo.Name.O)
  		req.AppendString(1, t.TableInfo.Name.O)
  		req.AppendUint64(2, t.Response.Checksum)
  		req.AppendUint64(3, t.Response.TotalKvs)
  		req.AppendUint64(4, t.Response.TotalBytes)
  	}
  	e.done = true
  	return nil
  }
docs: // Next implements the Executor Next interface.