相关疑难解决方法(0)

我一直认为数据集/数据帧API是相同的......唯一的区别是数据集API将为您提供编译时安全性.对 ？

那么......我的案子非常简单:

 case class Player (playerID: String, birthYear: Int)

 val playersDs: Dataset[Player] = session.read
  .option("header", "true")
  .option("delimiter", ",")
  .option("inferSchema", "true")
  .csv(PeopleCsv)
  .as[Player]

 // Let's try to find players born in 1999. 
 // This will work, you have compile time safety... but it will not use predicate pushdown!!!
 playersDs.filter(_.birthYear == 1999).explain()

 // This will work as expected and use predicate pushdown!!!
 // But you can't have compile time safety with this :(
 playersDs.filter('birthYear === 1999).explain()

从第一个示例解释将显示它不执行谓词下推(注意空PushedFilters):

== Physical Plan == …