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Posted to issues@spark.apache.org by "Peter Toth (Jira)" <ji...@apache.org> on 2020/07/09 12:41:00 UTC
[jira] [Updated] (SPARK-32241) Remove empty children of union
[ https://issues.apache.org/jira/browse/SPARK-32241?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Peter Toth updated SPARK-32241:
-------------------------------
Description:
Empty relation children of a union can be removed.
e.g. the plan of
{noformat}
SELECT c AS x FROM t1 UNION ALL SELECT * FROM t1 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}
was:
Empty relation children of a union can be removed.
e.g. the plan of
{noformat}
SELECT c AS x FROM t1 UNION ALL SELECT * FROM t1 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}
> 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
> Priority: Minor
>
> Empty relation children of a union can be removed.
> e.g. the plan of
> {noformat}
> SELECT c AS x FROM t1 UNION ALL SELECT * FROM t1 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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