spark中各种连接操作以及实用方法，spark连接实用方法, val a =

spark中各种连接操作以及实用方法，spark连接实用方法, val a =

     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))           */