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https://issues.apache.org/jira/browse/HIVE-28196?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Denys Kuzmenko updated HIVE-28196:
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    Status: Patch Available  (was: Open)

> Preserve column stats when applying UDF upper/lower.
> ----------------------------------------------------
>
>                 Key: HIVE-28196
>                 URL: https://issues.apache.org/jira/browse/HIVE-28196
>             Project: Hive
>          Issue Type: Improvement
>    Affects Versions: 4.0.0
>            Reporter: Seonggon Namgung
>            Assignee: Seonggon Namgung
>            Priority: Major
>              Labels: hive-4.0.1-must, performance, pull-request-available
>             Fix For: 4.1.0
>
>
> Current Hive re-estimates column stats (including avgColLen) when it 
> encounters UDF.
> In the case of upper and lower, Hive sets avgColLen to 
> hive.stats.max.variable.length.
> But these UDFs do not change column stats and the default value(100) is too 
> high for string type key columns, on which upper/lower are usually applied.
> This patch keeps input data's avgColLen after applying UDF upper/lower to 
> make a better query plan.



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