Github user gatorsmile commented on a diff in the pull request:
https://github.com/apache/spark/pull/10577#discussion_r48820999
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
---
@@ -595,6 +598,22 @@ object BooleanSimplification extends Rule[LogicalPlan]
with PredicateHelper {
}
/**
+ * Combines all adjacent [[Union]] and [[Unions]] operators into a single
[[Unions]].
+ */
+object CombineUnions extends Rule[LogicalPlan] {
+ private def collectUnionChildren(plan: LogicalPlan): Seq[LogicalPlan] =
plan match {
+ case Union(l, r) => collectUnionChildren(l) ++ collectUnionChildren(r)
--- End diff --
To do this at construction time, we need to introduce a new Dataframe API
`unionAll` that can combine more than two Dataframes? @marmbrus @rxin
Is my understanding correct? Thank you!
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
