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Posted to issues@kylin.apache.org by "Shaoxiong Zhan (JIRA)" <ji...@apache.org> on 2018/06/21 10:09:00 UTC

[jira] [Assigned] (KYLIN-3423) Performance improvement in FactDistinctColumnsMapper

     [ https://issues.apache.org/jira/browse/KYLIN-3423?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Shaoxiong Zhan reassigned KYLIN-3423:
-------------------------------------

    Assignee: Shaoxiong Zhan

> 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
>
> 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
>  * Use available mapper memory to de-dup before write to mapper output.
>  * For non-dictionary dimension column, only write min/max value to mapper output.
>  



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