spark中各種連接操作以及實用方法

     val a = sc.parallelize(Array(("123",4.0),("456",9.0),("789",9.0))

         val b = sc.parallelize(Array(("123",8.0),("789",10)))


    val c = a.join(b)  
    c.foreach(println)  
    /*  
    (123,(4.0,8.0))  
    (789,(9.0,10))  
     */  
    val d = a.cogroup(b)  
    d.foreach(println)  
    /*  
    (456,(CompactBuffer(9.0),CompactBuffer()))  
    (123,(CompactBuffer(4.0),CompactBuffer(8.0)))  
    (789,(CompactBuffer(9.0),CompactBuffer(10)))  
    */  
    val e = a.leftOuterJoin(b)  
    e.foreach(println)  
    /*  
      (456,(9.0,None))  
      (123,(4.0,Some(8.0)))  
      (789,(9.0,Some(10)))  
      */  
    val f = a.fullOuterJoin(b)  
    f.foreach(println)  
    /*  
      (456,(Some(9.0),None))  
      (123,(Some(4.0),Some(8.0)))  
      (789,(Some(9.0),Some(10)))  
      */  
    val g = a.cartesian(b)  
    g.foreach(println)  
    /*  
((123,4.0),(123,8.0))  
((123,4.0),(789,10))  
((456,9.0),(123,8.0))  
((456,9.0),(789,10))  
((789,9.0),(123,8.0))  
((789,9.0),(789,10))  
      */  
    /*val h = a.coalesce(6,true)  
    h.foreach(println)  
    a.dependencies.foreach(println)*/  
    val i = a.keyBy{case (k,v)=>("haha",234)}  
    i.foreach(println)  
    /*  
      ((haha,234),(123,4.0))  
      ((haha,234),(456,9.0))  
      ((haha,234),(789,9.0))  
     */  </pre>