code: func (p *PointGetPlan) ExplainInfo() string {
  	buffer := bytes.NewBufferString("")
  	tblName := p.TblInfo.Name.O
  	fmt.Fprintf(buffer, "table:%s", tblName)
  	if p.IndexInfo != nil {
  		fmt.Fprintf(buffer, ", index:")
  		for i, col := range p.IndexInfo.Columns {
  			buffer.WriteString(col.Name.O)
  			if i < len(p.IndexInfo.Columns)-1 {
  				buffer.WriteString(" ")
  			}
  		}
  	} else {
  		fmt.Fprintf(buffer, ", handle:%d", p.Handle)
  	}
  	return buffer.String()
  }
docs: // ExplainInfo returns operator information to be explained.