Github user rxin commented on the issue:
https://github.com/apache/spark/pull/17711
I feel both are pretty complicated. Can we just do something similar to
CombineUnion:
```
/**
* Combines all adjacent [[Union]] operators into a single [[Union]].
*/
object CombineUnions extends Rule[LogicalPlan] {
def apply(plan: LogicalPlan): LogicalPlan = plan transformDown {
case u: Union => flattenUnion(u, false)
case Distinct(u: Union) => Distinct(flattenUnion(u, true))
}
private def flattenUnion(union: Union, flattenDistinct: Boolean): Union =
{
val stack = mutable.Stack[LogicalPlan](union)
val flattened = mutable.ArrayBuffer.empty[LogicalPlan]
while (stack.nonEmpty) {
stack.pop() match {
case Distinct(Union(children)) if flattenDistinct =>
stack.pushAll(children.reverse)
case Union(children) =>
stack.pushAll(children.reverse)
case child =>
flattened += child
}
}
Union(flattened)
}
}```
It's going to be simpler because you don't need to handle distinct here.
---
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]
