[GitHub] [spark] HyukjinKwon commented on a change in pull request #29166: [SPARK-32280][SPARK-32372][SQL] ResolveReferences.dedupRight should only rewrite attributes for ancestor nodes of the conflict plan

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

HyukjinKwon commented on a change in pull request #29166:
URL: https://github.com/apache/spark/pull/29166#discussion_r460545971



##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
##########
@@ -1237,20 +1250,50 @@ class Analyzer(
       if (conflictPlans.isEmpty) {
         right
       } else {
-        val attributeRewrites = AttributeMap(conflictPlans.flatMap {
-          case (oldRelation, newRelation) => oldRelation.output.zip(newRelation.output)})
-        val conflictPlanMap = conflictPlans.toMap
-        // transformDown so that we can replace all the old Relations in one turn due to
-        // the reason that `conflictPlans` are also collected in pre-order.
-        right transformDown {
-          case r => conflictPlanMap.getOrElse(r, r)
-        } transformUp {
-          case other => other transformExpressions {
+        rewritePlan(right, conflictPlans.toMap)._1
+      }
+    }
+
+    private def rewritePlan(plan: LogicalPlan, conflictPlanMap: Map[LogicalPlan, LogicalPlan])
+      : (LogicalPlan, Seq[(Attribute, Attribute)]) = {
+      if (conflictPlanMap.contains(plan)) {
+        // If the plan is the one that conflict the with left one, we'd
+        // just replace it with the new plan and collect the rewrite
+        // attributes for the parent node.
+        val newRelation = conflictPlanMap(plan)
+        newRelation -> plan.output.zip(newRelation.output)
+      } else {
+        val attrMapping = new mutable.ArrayBuffer[(Attribute, Attribute)]()
+        val newPlan = plan.mapChildren { child =>
+          // If not, we'd rewrite child plan recursively until we find the
+          // conflict node or reach the leaf node.
+          val (newChild, childAttrMapping) = rewritePlan(child, conflictPlanMap)
+          attrMapping ++= childAttrMapping.filter { case (oldAttr, _) =>
+            // `attrMapping` is not only used to replace the attributes of the current `plan`,
+            // but also to be propagated to the parent plans of the current `plan`. Therefore,
+            // the `oldAttr` must be part of either `plan.references` (so that it can be used to
+            // replace attributes of the current `plan`) or `plan.outputSet` (so that it can be
+            // used by those parent plans).
+            (plan.outputSet ++ plan.references).contains(oldAttr)
+          }
+          newChild
+        }
+
+        if (attrMapping.isEmpty) {
+          newPlan -> attrMapping

Review comment:
       Thanks for letting me know. +1




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