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Posted to issues@kylin.apache.org by "Feng Zhu (Jira)" <ji...@apache.org> on 2021/01/27 13:00:00 UTC

[jira] [Assigned] (KYLIN-4888) Performance optimization of union query with spark engine

     [ https://issues.apache.org/jira/browse/KYLIN-4888?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Feng Zhu reassigned KYLIN-4888:
-------------------------------

    Assignee: Feng Zhu

>  Performance optimization of union query with spark engine
> ----------------------------------------------------------
>
>                 Key: KYLIN-4888
>                 URL: https://issues.apache.org/jira/browse/KYLIN-4888
>             Project: Kylin
>          Issue Type: Improvement
>          Components: Spark Engine
>    Affects Versions: v4.0.0-alpha
>            Reporter: Feng Zhu
>            Assignee: Feng Zhu
>            Priority: Major
>             Fix For: v4.0.0-beta
>
>
> when using union query with spark engine, UnionPlan transforms OLAPUnionRel to spark
> DataFrame, when OLAPUnionRel.all = false, distinct transformation of spark will be used, but
> it's used in a loop which traversing the DataFrame collection so that there are so many stages in spark dag.  Actuall, distinct transformation should be used only once at last.



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