maropu commented on a change in pull request #31595:
URL: https://github.com/apache/spark/pull/31595#discussion_r581500501
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
##########
@@ -501,6 +502,46 @@ object RemoveNoopOperators extends Rule[LogicalPlan] {
}
}
+/**
+ * Remove no-op `Union` from the query plan that do not make any modifications.
+ */
+object RemoveNoopUnion extends Rule[LogicalPlan] {
+ /**
+ * This only removes the `Project` that has only attributes or aliased
attributes
+ * from its child.
+ */
+ private def removeAliasOnlyProject(plan: LogicalPlan): LogicalPlan = plan
match {
+ case p @ Project(projectList, child) =>
+ val originalOutputs = projectList.collect {
Review comment:
nit: `originalOutput`?
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
##########
@@ -501,6 +502,46 @@ object RemoveNoopOperators extends Rule[LogicalPlan] {
}
}
+/**
+ * Remove no-op `Union` from the query plan that do not make any modifications.
+ */
+object RemoveNoopUnion extends Rule[LogicalPlan] {
+ /**
+ * This only removes the `Project` that has only attributes or aliased
attributes
+ * from its child.
+ */
+ private def removeAliasOnlyProject(plan: LogicalPlan): LogicalPlan = plan
match {
+ case p @ Project(projectList, child) =>
+ val originalOutputs = projectList.collect {
+ case Alias(a: Attribute, _) => a
+ case a: Attribute => a
+ }
+ if (child.output.size == p.output.size && child.output ==
originalOutputs) {
+ child
+ } else {
+ p
+ }
+ case _ => plan
+ }
+
+ private def removeUnion(u: Union): Option[LogicalPlan] = {
+ val unionChildren = u.children.map(c => removeAliasOnlyProject(c))
Review comment:
nit: `val unionChildren = u.children.map(removeAliasOnlyProject)`
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
##########
@@ -501,6 +502,46 @@ object RemoveNoopOperators extends Rule[LogicalPlan] {
}
}
+/**
+ * Remove no-op `Union` from the query plan that do not make any modifications.
+ */
+object RemoveNoopUnion extends Rule[LogicalPlan] {
+ /**
+ * This only removes the `Project` that has only attributes or aliased
attributes
+ * from its child.
+ */
+ private def removeAliasOnlyProject(plan: LogicalPlan): LogicalPlan = plan
match {
+ case p @ Project(projectList, child) =>
Review comment:
How about a `Aggregate` case?
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