code: func (s *StatsInfo) Scale(factor float64) *StatsInfo {
  	profile := &StatsInfo{
  		RowCount:     s.RowCount * factor,
  		Cardinality:  make([]float64, len(s.Cardinality)),
  		HistColl:     s.HistColl,
  		StatsVersion: s.StatsVersion,
  	}
  	for i := range profile.Cardinality {
  		profile.Cardinality[i] = s.Cardinality[i] * factor
  	}
  	return profile
  }
docs: // Scale receives a selectivity and multiplies it with RowCount and Cardinality.