[jira] [Commented] (KYLIN-4941) Support encoding raw data to base cuboid column-by-column

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KYLIN-4941?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17320044#comment-17320044 ] 

ASF GitHub Bot commented on KYLIN-4941:
---------------------------------------

zhengshengjun opened a new pull request #1631:
URL: https://github.com/apache/kylin/pull/1631


   ## Proposed changes
   
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> Support encoding raw data to base cuboid column-by-column
> ---------------------------------------------------------
>
>                 Key: KYLIN-4941
>                 URL: https://issues.apache.org/jira/browse/KYLIN-4941
>             Project: Kylin
>          Issue Type: Improvement
>          Components: Job Engine
>    Affects Versions: v3.1.1
>            Reporter: ShengJun Zheng
>            Assignee: ShengJun Zheng
>            Priority: Major
>             Fix For: v3.2.0
>
>
> When building with spark engine, the first step is to encode hive table's row to base cuboid data.
> The existing implementation is encoding row by row. If the cube has several dictionary encoded measures, it has to use all dictionaries at the same time to encode a single row. This causes heavy memory usage, and low cache hit ratio of dictionary cache.
> We optimized this case by encoding column by column, and it did bring significant improvement over cubes with several high cardinality dictionaries-encoded measures.
> We will refine the implementation based on KYLIN3.x and share it out.



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