ulysses-you commented on code in PR #43841:
URL: https://github.com/apache/spark/pull/43841#discussion_r1396615662
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sql/core/src/main/scala/org/apache/spark/sql/execution/exchange/EnsureRequirements.scala:
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@@ -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:
My point is that, it's a user-specified shuffle, we can not just remove it.
Does it affect shuffle reuse ? e.g.,
```
with t (select /*+ repartition */ * from t)
select * from t join t2
union all
select * from t
```
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