[GitHub] [spark] cloud-fan commented on a diff in pull request #37519: [SPARK-40050][SQL] Eliminate the `Sort` if there is a `LocalLimit` between `Join` and `Sort`

[GitBox <gi...@apache.org>]

cloud-fan commented on code in PR #37519:
URL: https://github.com/apache/spark/pull/37519#discussion_r947697059


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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala:
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@@ -1528,8 +1528,8 @@ object EliminateSorts extends Rule[LogicalPlan] {
       applyLocally.lift(child).getOrElse(child)
     case s @ Sort(_, global, child) => s.copy(child = recursiveRemoveSort(child, global))
     case j @ Join(originLeft, originRight, _, cond, _) if cond.forall(_.deterministic) =>
-      j.copy(left = recursiveRemoveSort(originLeft, true),
-        right = recursiveRemoveSort(originRight, true))
+      j.copy(left = recursiveRemoveSort(originLeft, true, canEliminateThroughLocalLimit = true),
+        right = recursiveRemoveSort(originRight, true, canEliminateThroughLocalLimit = true))
     case g @ Aggregate(_, aggs, originChild) if isOrderIrrelevantAggs(aggs) =>
       g.copy(child = recursiveRemoveSort(originChild, true))

Review Comment:
   I think aggregate can eliminate sort through local limit as well. The point is, local limit does not guarantee any semantic (the result depends on the data partitioning) and end-users won't have any expectations for it.



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