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https://issues.apache.org/jira/browse/KYLIN-3423?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16528683#comment-16528683
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ASF subversion and git services commented on KYLIN-3423:
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Commit bc08681850090f05d3c6d21dad16acee52244a14 in kylin's branch 
refs/heads/sync from ZhansShaoxiong
[ https://gitbox.apache.org/repos/asf?p=kylin.git;h=bc08681 ]

KYLIN-3423 Performance improvement in FactDistinctColumnsMapper


> Performance improvement in FactDistinctColumnsMapper
> ----------------------------------------------------
>
>                 Key: KYLIN-3423
>                 URL: https://issues.apache.org/jira/browse/KYLIN-3423
>             Project: Kylin
>          Issue Type: Improvement
>            Reporter: liyang
>            Assignee: Shaoxiong Zhan
>            Priority: Major
>             Fix For: v2.5.0
>
>
> Currently FactDistinctColumnsMapper writes every cell to mapper output. In 
> spite of mapper side Combiner, we could do better de-dup using available 
> mapper memory.
> The situation becomes worse after KYLIN-3370, because not only dictionary 
> columns, now it is every dimension column get written as mapper output.
> Suggest
>  * For non-dictionary dimension column, only write min/max value to mapper 
> output.
>  



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