[GitHub] [spark] yaooqinn commented on a diff in pull request #42453: [SPARK-43979][SQL][FOLLOWUP] Fix the detection of alias-only project

["yaooqinn (via GitHub)" <gi...@apache.org>]

yaooqinn commented on code in PR #42453:
URL: https://github.com/apache/spark/pull/42453#discussion_r1291416529


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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CheckAnalysis.scala:
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@@ -1113,9 +1113,12 @@ trait CheckAnalysis extends PredicateHelper with LookupCatalog with QueryErrorsB
   private def simplifyPlanForCollectedMetrics(plan: LogicalPlan): LogicalPlan = {
     plan.resolveOperators {
       case p: Project if p.projectList.size == p.child.output.size =>
-        val assignExprIdOnly = p.projectList.zip(p.child.output).forall {
-          case (left: Alias, right: Attribute) =>
-            left.child.semanticEquals(right) && right.name == left.name
+        val assignExprIdOnly = p.projectList.zipWithIndex.forall {
+          case (Alias(attr: AttributeReference, _), index) =>
+            // The input plan of this method is already canonicalized. The attribute id becomes the
+            // ordinal of this attribute in the child outputs. So an alias-only Project means the
+            // the id of the aliased attribute is the same as its index in the project list.

Review Comment:
   nit: duplicated `the` but might not be worth fixing



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