[GitHub] [spark] imback82 commented on a change in pull request #29166: [SPARK-32372][SQL] ResolveReferences.dedupRight should only rewrite attributes for ancestor nodes of the conflict plan

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

imback82 commented on a change in pull request #29166:
URL: https://github.com/apache/spark/pull/29166#discussion_r458296015



##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
##########
@@ -1237,20 +1250,43 @@ 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
+          newChild
+        }
+
+        if (attrMapping.isEmpty) {
+          newPlan -> attrMapping
+        } else {
+          assert(!attrMapping.groupBy(_._1.exprId)
+            .exists(_._2.map(_._2.exprId).distinct.length > 1),
+            "Found duplicate rewrite attributes")

Review comment:
       When the query from [SPARK-32280](https://issues.apache.org/jira/browse/SPARK-32280) is run, I believe this assert is hit. Should this be an assert or should we throw an AnalysisException?




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