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https://issues.apache.org/jira/browse/KYLIN-3729?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Fangyuan Deng updated KYLIN-3729:
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Attachment: KYLIN-3729.patch
> CLUSTER BY CAST(field AS STRING) will accelerate base cuboid build with UHC
> global dict
> ---------------------------------------------------------------------------------------
>
> Key: KYLIN-3729
> URL: https://issues.apache.org/jira/browse/KYLIN-3729
> Project: Kylin
> Issue Type: Improvement
> Components: Job Engine
> Affects Versions: v2.5.2
> Reporter: Fangyuan Deng
> Assignee: Fangyuan Deng
> Priority: Minor
> Attachments: KYLIN-3729.patch, image-2018-12-19-12-01-20-430.png,
> image-2018-12-19-12-02-08-913.png
>
>
> As we know global dict is a sliced appendTrieTree using cache-loader , so if
> we convert values to ids using global dict, ordered values will help.
> And now we can set kylin.source.hive.flat-table-cluster-by-dict-column = uhc
> column, to make source data CLUSTER BY uhc-column, this get better.
> But the appendTrieTree is order by string, so we can CLUSTER BY
> CAST(uhc-column AS STRING), to optimize most.
> We can see the hdfs bytes read (most is global dict) reduce to 30%
> !image-2018-12-19-12-01-20-430.png!!image-2018-12-19-12-02-08-913.png!
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