Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/17175#discussion_r105240101
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/basicPhysicalOperators.scala
---
@@ -78,9 +78,42 @@ case class ProjectExec(projectList:
Seq[NamedExpression], child: SparkPlan)
}
}
- override def outputOrdering: Seq[SortOrder] = child.outputOrdering
--- End diff --
Well, if we wanna support this, we should support all the case. e.g.
```
Project [(a#1 + b#2) as c#3, b#2]
```
and then the parent operator requires partitioning on `c#3 - b#2`. Since
`(c#3 - b#2).samanticEquals(a#1)` is false, additional ShuffleExchange will be
added.
This is not trivial and we should have a holistic solution.
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