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From "ASF GitHub Bot (Jira)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-22893) Enhance data size estimation for fields computed by UDFs
Date Fri, 14 Feb 2020 16:42:00 GMT

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

ASF GitHub Bot updated HIVE-22893:
----------------------------------
    Labels: pull-request-available  (was: )

> 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
>              Labels: pull-request-available
>         Attachments: HIVE-22893.01.patch
>
>
> 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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