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Using Scala version 2.11.12 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_121)
Type in expressions to have them evaluated.
Type :help for more information.union
def union(other: RDD[T]): RDD[T]
该函数比较简单，就是将两个RDD进行合并，不去重。
scala> var rdd1 = sc.makeRDD(1 to 2,1)
rdd1: org.apache.spark.rdd.RDD[Int] = ParallelCollectionRDD[45] at makeRDD at :21
scala> rdd1.collect
res42: Array[Int] = Array(1, 2)
scala> var rdd2 = sc.makeRDD(2 to 3,1)
rdd2: org.apache.spark.rdd.RDD[