diff --git a/src/main/scala/catalyst/execution/PlanningStrategies.scala b/src/main/scala/catalyst/execution/PlanningStrategies.scala
index fd9e5e291d98b..10f0f051bddc8 100644
--- a/src/main/scala/catalyst/execution/PlanningStrategies.scala
+++ b/src/main/scala/catalyst/execution/PlanningStrategies.scala
@@ -143,10 +143,11 @@ trait PlanningStrategies {
   object BasicOperators extends Strategy {
     def apply(plan: LogicalPlan): Seq[SharkPlan] = plan match {
       case logical.Sort(sortExprs, child) =>
-        // Set the requiredDistribution of this SortPartitions to OrderedDistribution.
+        // This sort is a global sort. Its requiredDistribution will be an OrderedDistribution.
         execution.Sort(sortExprs, true, planLater(child)):: Nil
       case logical.SortPartitions(sortExprs, child) =>
-        // Set the requiredDistribution of this SortPartitions to UnspecifiedDistribution.
+        // This sort only sort tuples within a partition. Its requiredDistribution will be
+        // an UnspecifiedDistribution.
         execution.Sort(sortExprs, false, planLater(child)) :: Nil
       case logical.Project(projectList, child) =>
         execution.Project(projectList, planLater(child)) :: Nil