Spark當中做二次排序非常簡單，因為有大量的現成函式已經實現了，只需要進行組合運用就好

在這裡進行一下二次排序的總結

如果對兩列或多列同時進行升序或降序排序的話比較容易實現

初始資料

1.兩次升序或降序

    val dataset = //your dataset
    //1
    dataset.map(x => (x._1, x._2)).sortBy(x => x, false).collect.foreach(println)

class SortByTwice(val first: Int, val second: Int) extends Ordered[SortByTwice] with Serializable {
  def compare(that: SortByTwice): Int = {
    if (this.first - that.first != 0) {
      return that.first - this.first
    } else {
      return this.second - that.second
    }
  }
}


 val dataset = //your dataset
 dataset.map(line => (new SortByTwice(line._1.toInt, line._2.toInt))).sortBy(x => x).map(x => (x.first, x.second)).collect.foreach(println)
 

val dataset = //your dataset
dataset.groupByKey.map(x => (x._1, x._2.toList.sortWith(_ > _))).collect.foreach(println)