Change docs on 'reduce' since the merging of local reduces no longer preserves

ordering, so the reduce function must also be commutative.

2 files changed, 2 insertions, 2 deletions

diff --git a/core/src/main/scala/spark/RDD.scala b/core/src/main/scala/spark/RDD.scala
index d15c6f7396..3ad3b4d233 100644
--- a/core/src/main/scala/spark/RDD.scala
+++ b/core/src/main/scala/spark/RDD.scala
@@ -330,7 +330,7 @@ abstract class RDD[T: ClassManifest](@transient sc: SparkContext) extends Serial
   def toArray(): Array[T] = collect()
 
   /**
-   * Reduces the elements of this RDD using the specified associative binary operator.
+   * Reduces the elements of this RDD using the specified commutative and associative binary operator.
    */
   def reduce(f: (T, T) => T): T = {
     val cleanF = sc.clean(f)
diff --git a/core/src/main/scala/spark/api/java/JavaRDDLike.scala b/core/src/main/scala/spark/api/java/JavaRDDLike.scala
index 81d3a94466..6da89f518f 100644
--- a/core/src/main/scala/spark/api/java/JavaRDDLike.scala
+++ b/core/src/main/scala/spark/api/java/JavaRDDLike.scala
@@ -201,7 +201,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
   }
 
   /**
-   * Reduces the elements of this RDD using the specified associative binary operator.
+   * Reduces the elements of this RDD using the specified commutative and associative binary operator.
    */
   def reduce(f: JFunction2[T, T, T]): T = rdd.reduce(f)