[GitHub] [spark] cloud-fan commented on a diff in pull request #37284: [SPARK-39867][SQL] Global limit should not inherit OrderPreservingUnaryNode

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

cloud-fan commented on code in PR #37284:
URL: https://github.com/apache/spark/pull/37284#discussion_r930692755


##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicLogicalOperators.scala:
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@@ -1430,9 +1430,13 @@ object Limit {
 /**
  * A global (coordinated) limit. This operator can emit at most `limitExpr` number in total.
  *
+ * We can not make it inherit [[OrderPreservingUnaryNode]] due to the different strategy of
+ * physical plan. The output ordering of child will be broken if a shuffle exchange comes in
+ * between the child and global limit.

Review Comment:
   ```suggestion
    * between the child and global limit, due to the fact that shuffle reader fetches blocks in random order.
   ```



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