[GitHub] [spark] cloud-fan commented on a change in pull request #28318: [SPARK-31535][SQL] Fix nested CTE substitution

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

cloud-fan commented on a change in pull request #28318:
URL: https://github.com/apache/spark/pull/28318#discussion_r414235827



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File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CTESubstitution.scala
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@@ -31,53 +31,43 @@ object CTESubstitution extends Rule[LogicalPlan] {
   def apply(plan: LogicalPlan): LogicalPlan = {
     LegacyBehaviorPolicy.withName(SQLConf.get.getConf(LEGACY_CTE_PRECEDENCE_POLICY)) match {
       case LegacyBehaviorPolicy.EXCEPTION =>
-        assertNoNameConflictsInCTE(plan, inTraverse = false)
-        traverseAndSubstituteCTE(plan, inTraverse = false)
+        assertNoNameConflictsInCTE(plan)
+        traverseAndSubstituteCTE(plan)
       case LegacyBehaviorPolicy.LEGACY =>
         legacyTraverseAndSubstituteCTE(plan)
       case LegacyBehaviorPolicy.CORRECTED =>
-        traverseAndSubstituteCTE(plan, inTraverse = false)
+        traverseAndSubstituteCTE(plan)
     }
   }
 
   /**
    * Check the plan to be traversed has naming conflicts in nested CTE or not, traverse through
-   * child, innerChildren and subquery for the current plan.
+   * child, innerChildren and subquery expressions for the current plan.
    */
   private def assertNoNameConflictsInCTE(
       plan: LogicalPlan,
-      inTraverse: Boolean,
-      cteNames: Set[String] = Set.empty): Unit = {
-    plan.foreach {
+      namesInChildren: Set[String] = Set.empty,
+      namesInExpressions: Set[String] = Set.empty): Unit = {

Review comment:
       Why do we separate children and expression? Can we just have one parameter `outerNames`?




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