viirya commented on a change in pull request #29643:
URL: https://github.com/apache/spark/pull/29643#discussion_r483211691
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/QueryPlan.scala
##########
@@ -168,6 +170,85 @@ abstract class QueryPlan[PlanType <: QueryPlan[PlanType]]
extends TreeNode[PlanT
}.toSeq
}
+
+ /**
+ * Rewrites this plan tree based on the given plan mappings from old plan
nodes to new nodes.
+ * This method also updates all the related references in this plan tree
accordingly, in case
+ * the replaced node has different output expr ID than the old node.
+ */
+ def rewriteWithPlanMapping(
+ planMapping: Map[PlanType, PlanType],
+ canGetOutput: PlanType => Boolean = _ => true): PlanType = {
+ def internalRewrite(plan: PlanType): (PlanType, Seq[(Attribute,
Attribute)]) = {
+ if (planMapping.contains(plan)) {
+ val newPlan = planMapping(plan)
+ val attrMapping = if (canGetOutput(plan) && canGetOutput(newPlan)) {
+ plan.output.zip(newPlan.output).filter {
+ case (a1, a2) => a1.exprId != a2.exprId
+ }
+ } else {
+ Nil
+ }
+ newPlan -> attrMapping
+ } else {
+ val attrMapping = new mutable.ArrayBuffer[(Attribute, Attribute)]()
+ val newPlan = plan.mapChildren { child =>
+ val (newChild, childAttrMapping) = internalRewrite(child)
+ 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)
Review comment:
oh, we don't check if `plan` is resolved here, and `plan.outputSet` can
cause error.
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