code: func (p *Limit) convert2PhysicalPlan(prop *requiredProperty) (*physicalPlanInfo, error) {
  	info, err := p.getPlanInfo(prop)
  	if err != nil {
  		return nil, errors.Trace(err)
  	}
  	if info != nil {
  		return info, nil
  	}
  	info, err = p.GetChildByIndex(0).(LogicalPlan).convert2PhysicalPlan(limitProperty(&Limit{Offset: p.Offset, Count: p.Count}))
  	if err != nil {
  		return nil, errors.Trace(err)
  	}
  	info = enforceProperty(prop, info)
  	p.storePlanInfo(prop, info)
  	return info, nil
  }
docs: // convert2PhysicalPlan implements the LogicalPlan convert2PhysicalPlan interface.