[GitHub] [spark] wangyum commented on a diff in pull request #37565: [SPARK-40137][SQL] Combines limits after projection

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

wangyum commented on code in PR #37565:
URL: https://github.com/apache/spark/pull/37565#discussion_r949749115


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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala:
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@@ -1994,6 +1994,13 @@ object EliminateLimits extends Rule[LogicalPlan] {
       LocalLimit(Literal(Least(Seq(ne, le)).eval().asInstanceOf[Int]), grandChild)
     case Limit(le, Limit(ne, grandChild)) =>
       Limit(Literal(Least(Seq(ne, le)).eval().asInstanceOf[Int]), grandChild)
+
+    case Project(projectList, Limit(l, child)) =>

Review Comment:
   `projectList` may contain very heavy UDFs. This change may increase `Project` evaluation cost.



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