[jira] [Assigned] (HIVE-22893) Enhance data size estimation for fields computed by UDFs

["Zoltan Haindrich (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-22893?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Zoltan Haindrich reassigned HIVE-22893:
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> Enhance data size estimation for fields computed by UDFs
> --------------------------------------------------------
>
>                 Key: HIVE-22893
>                 URL: https://issues.apache.org/jira/browse/HIVE-22893
>             Project: Hive
>          Issue Type: Improvement
>          Components: Statistics
>            Reporter: Zoltan Haindrich
>            Assignee: Zoltan Haindrich
>            Priority: Major
>
> Right now if we have columnstat on a coumn ; we use that to estimate things about the column; - however if an UDF is executed on a column ; the resulting column is treated as unknown thing and defaults are assumed.
> An impovement could be to give wide estimation(s) in case of frequently used udf.
> For example; consider {{substr(c,1,1)}} ; no matter what the input; the output is at most a 1 long string



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