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Posted to issues@spark.apache.org by "Apache Spark (JIRA)" <ji...@apache.org> on 2016/02/08 22:05:39 UTC
[jira] [Commented] (SPARK-13235) Remove extra Distinct in Union
Distinct
[ https://issues.apache.org/jira/browse/SPARK-13235?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15137682#comment-15137682 ]
Apache Spark commented on SPARK-13235:
--------------------------------------
User 'gatorsmile' has created a pull request for this issue:
https://github.com/apache/spark/pull/11120
> Remove extra Distinct in Union Distinct
> ---------------------------------------
>
> Key: SPARK-13235
> URL: https://issues.apache.org/jira/browse/SPARK-13235
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 2.0.0
> Reporter: Xiao Li
>
> Union Distinct has two Distinct that generates two Aggregation in the plan.
> {code}
> sql("select * from t0 union select * from t0").explain(true)
> {code}
> {code}
> == Parsed Logical Plan ==
> 'Project [unresolvedalias(*,None)]
> +- 'Subquery u_2
> +- 'Distinct
> +- 'Project [unresolvedalias(*,None)]
> +- 'Subquery u_1
> +- 'Distinct
> +- 'Union
> :- 'Project [unresolvedalias(*,None)]
> : +- 'UnresolvedRelation `t0`, None
> +- 'Project [unresolvedalias(*,None)]
> +- 'UnresolvedRelation `t0`, None
> == Analyzed Logical Plan ==
> id: bigint
> Project [id#16L]
> +- Subquery u_2
> +- Distinct
> +- Project [id#16L]
> +- Subquery u_1
> +- Distinct
> +- Union
> :- Project [id#16L]
> : +- Subquery t0
> : +- Relation[id#16L] ParquetRelation
> +- Project [id#16L]
> +- Subquery t0
> +- Relation[id#16L] ParquetRelation
> == Optimized Logical Plan ==
> Aggregate [id#16L], [id#16L]
> +- Aggregate [id#16L], [id#16L]
> +- Union
> :- Project [id#16L]
> : +- Relation[id#16L] ParquetRelation
> +- Project [id#16L]
> +- Relation[id#16L] ParquetRelation
> {code}
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