dongjoon-hyun commented on a change in pull request #31595:
URL: https://github.com/apache/spark/pull/31595#discussion_r580766586
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
##########
@@ -501,6 +502,42 @@ object RemoveNoopOperators extends Rule[LogicalPlan] {
}
}
+/**
+ * Remove no-op `Union` from the query plan that do not make any modifications.
+ */
+object RemoveNoopUnion extends Rule[LogicalPlan] {
+ private def removeAliasOnlyProject(plan: LogicalPlan): LogicalPlan = plan
match {
+ case p @ Project(projectList, child) =>
+ val originalOutputs = projectList.collect {
Review comment:
@viirya Shall we have a test case suggested by @c21 suggested?
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
##########
@@ -157,6 +157,7 @@ abstract class Optimizer(catalogManager: CatalogManager)
// since the other rules might make two separate Unions operators
adjacent.
Batch("Union", Once,
RemoveNoopOperators,
+ RemoveNoopUnion,
Review comment:
Thank you for splitting the rule!
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