code: func (p PhysicalHashJoin) Init(ctx sessionctx.Context, stats *property.StatsInfo, props ...*property.PhysicalProperty) *PhysicalHashJoin {
  	tp := TypeHashRightJoin
  	if p.InnerChildIdx == 1 {
  		tp = TypeHashLeftJoin
  	}
  	p.basePhysicalPlan = newBasePhysicalPlan(ctx, tp, &p)
  	p.childrenReqProps = props
  	p.stats = stats
  	return &p
  }
docs: // Init initializes PhysicalHashJoin.