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https://issues.apache.org/jira/browse/SPARK-32241?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wenchen Fan resolved SPARK-32241.
---------------------------------
Fix Version/s: 3.1.0
Resolution: Fixed
Issue resolved by pull request 29053
[https://github.com/apache/spark/pull/29053]
> Remove empty children of union
> ------------------------------
>
> Key: SPARK-32241
> URL: https://issues.apache.org/jira/browse/SPARK-32241
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 3.1.0
> Reporter: Peter Toth
> Assignee: Peter Toth
> Priority: Minor
> Fix For: 3.1.0
>
>
> Empty relation children of a union can be removed.
> e.g. the plan of
> {noformat}
> SELECT c FROM t UNION ALL SELECT c FROM t WHERE FALSE{noformat}
> is currently:
> {noformat}
> == Physical Plan ==
> Union
> :- *(1) Project [value#219 AS c#222]
> : +- *(1) LocalTableScan [value#219]
> +- LocalTableScan <empty>, [c#224]{noformat}
> but it could be improved as:
> {noformat}
> == Physical Plan ==
> *(1) Project [value#219 AS c#222]
> +- *(1) LocalTableScan [value#219]{noformat}
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