diff --git a/core/src/main/scala/org/apache/spark/rdd/RDD.scala b/core/src/main/scala/org/apache/spark/rdd/RDD.scala index af9e31ba7b720..5072fa284af1e 100644 --- a/core/src/main/scala/org/apache/spark/rdd/RDD.scala +++ b/core/src/main/scala/org/apache/spark/rdd/RDD.scala @@ -1128,15 +1128,19 @@ abstract class RDD[T: ClassTag]( * @return an array of top elements */ def takeOrdered(num: Int)(implicit ord: Ordering[T]): Array[T] = { - mapPartitions { items => - // Priority keeps the largest elements, so let's reverse the ordering. - val queue = new BoundedPriorityQueue[T](num)(ord.reverse) - queue ++= util.collection.Utils.takeOrdered(items, num)(ord) - Iterator.single(queue) - }.reduce { (queue1, queue2) => - queue1 ++= queue2 - queue1 - }.toArray.sorted(ord) + if (num == 0) { + Array.empty + } else { + mapPartitions { items => + // Priority keeps the largest elements, so let's reverse the ordering. + val queue = new BoundedPriorityQueue[T](num)(ord.reverse) + queue ++= util.collection.Utils.takeOrdered(items, num)(ord) + Iterator.single(queue) + }.reduce { (queue1, queue2) => + queue1 ++= queue2 + queue1 + }.toArray.sorted(ord) + } } /** diff --git a/core/src/test/scala/org/apache/spark/rdd/RDDSuite.scala b/core/src/test/scala/org/apache/spark/rdd/RDDSuite.scala index 926d4fecb5b91..499dcda3dae8f 100644 --- a/core/src/test/scala/org/apache/spark/rdd/RDDSuite.scala +++ b/core/src/test/scala/org/apache/spark/rdd/RDDSuite.scala @@ -521,6 +521,13 @@ class RDDSuite extends FunSuite with SharedSparkContext { assert(sortedLowerK === Array(1, 2, 3, 4, 5)) } + test("takeOrdered with limit 0") { + val nums = Array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) + val rdd = sc.makeRDD(nums, 2) + val sortedLowerK = rdd.takeOrdered(0) + assert(sortedLowerK.size === 0) + } + test("takeOrdered with custom ordering") { val nums = Array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) implicit val ord = implicitly[Ordering[Int]].reverse