wangyum commented on code in PR #43841:
URL: https://github.com/apache/spark/pull/43841#discussion_r1396593112


##########
sql/core/src/main/scala/org/apache/spark/sql/execution/exchange/EnsureRequirements.scala:
##########
@@ -68,7 +68,13 @@ case class EnsureRequirements(
       case (child, distribution) =>
         val numPartitions = distribution.requiredNumPartitions
           .getOrElse(conf.numShufflePartitions)
-        ShuffleExchangeExec(distribution.createPartitioning(numPartitions), 
child, shuffleOrigin)
+        // Avoid generating redundant ShuffleExchangeExec node
+        val shuffleChild = child match {
+          case s: ShuffleExchangeExec => s.child
+          case other => other
+        }
+        ShuffleExchangeExec(
+          distribution.createPartitioning(numPartitions), shuffleChild, 
shuffleOrigin)

Review Comment:
   @ulysses-you It only takes effect if there are no operators between two 
shuffles.



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