allisonwang-db commented on a change in pull request #30659:
URL: https://github.com/apache/spark/pull/30659#discussion_r539001681
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File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/RemoveRedundantProjects.scala
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@@ -61,15 +63,24 @@ object RemoveRedundantProjects extends Rule[SparkPlan] {
val keepOrdering = a.aggregateExpressions
.exists(ae => ae.mode.equals(Final) || ae.mode.equals(PartialMerge))
a.mapChildren(removeProject(_, keepOrdering))
- // GenerateExec requires column ordering since it binds input rows
directly with its
- // requiredChildOutput without using child's output schema.
- case g: GenerateExec => g.mapChildren(removeProject(_, true))
- // JoinExec ordering requirement will inherit from its parent. If there
is no ProjectExec in
- // its ancestors, JoinExec should require output columns to be ordered.
- case o => o.mapChildren(removeProject(_, requireOrdering))
+ case p if canPassThrough(p) => p.mapChildren(removeProject(_,
requireOrdering))
Review comment:
Good question. This is because there might be other nodes that require
column ordering. An earlier PR also fixed a similar issue for GenerateExec. It
is safer to use a whitelist in order to prevent similar issues. Most existing
cases are covered (filter, aggregate and join). We can always add more nodes to
the whitelist if redundant projects are discovered.
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