[GitHub] [spark] viirya commented on a change in pull request #29643: [SPARK-32638][SQL][FOLLOWUP] move the plan rewriting methods to QueryPlan

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

viirya commented on a change in pull request #29643:
URL: https://github.com/apache/spark/pull/29643#discussion_r483192108



##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
##########
@@ -123,127 +123,6 @@ object AnalysisContext {
   }
 }
 
-object Analyzer {
-
-  /**
-   * Rewrites a given `plan` recursively based on rewrite mappings from old plans to new ones.
-   * This method also updates all the related references in the `plan` accordingly.
-   *
-   * @param plan to rewrite
-   * @param rewritePlanMap has mappings from old plans to new ones for the given `plan`.
-   * @return a rewritten plan and updated references related to a root node of
-   *         the given `plan` for rewriting it.
-   */
-  def rewritePlan(plan: LogicalPlan, rewritePlanMap: Map[LogicalPlan, LogicalPlan])
-    : (LogicalPlan, Seq[(Attribute, Attribute)]) = {
-    if (plan.resolved) {
-      val attrMapping = new mutable.ArrayBuffer[(Attribute, Attribute)]()
-      val newChildren = plan.children.map { 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, rewritePlanMap)
-        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
-      }
-
-      val newPlan = if (rewritePlanMap.contains(plan)) {
-        rewritePlanMap(plan).withNewChildren(newChildren)
-      } else {
-        plan.withNewChildren(newChildren)
-      }
-
-      assert(!attrMapping.groupBy(_._1.exprId)
-        .exists(_._2.map(_._2.exprId).distinct.length > 1),
-        "Found duplicate rewrite attributes")
-
-      val attributeRewrites = AttributeMap(attrMapping)
-      // Using attrMapping from the children plans to rewrite their parent node.
-      // Note that we shouldn't rewrite a node using attrMapping from its sibling nodes.
-      val p = newPlan.transformExpressions {
-        case a: Attribute =>
-          updateAttr(a, attributeRewrites)
-        case s: SubqueryExpression =>
-          s.withNewPlan(updateOuterReferencesInSubquery(s.plan, attributeRewrites))
-      }
-      attrMapping ++= plan.output.zip(p.output)
-        .filter { case (a1, a2) => a1.exprId != a2.exprId }
-      p -> attrMapping
-    } else {
-      // Just passes through unresolved nodes
-      plan.mapChildren {

Review comment:
       Good catch! In this unresolved plan, there might be other resolved and replaced attributes.




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