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

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

     [ https://issues.apache.org/jira/browse/HIVE-22893?focusedWorklogId=387469&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-387469 ]

ASF GitHub Bot logged work on HIVE-22893:
-----------------------------------------

                Author: ASF GitHub Bot
            Created on: 14/Feb/20 16:41
            Start Date: 14/Feb/20 16:41
    Worklog Time Spent: 10m 
      Work Description: kgyrtkirk commented on pull request #915: HIVE-22893 StatEstimate
URL: https://github.com/apache/hive/pull/915
 
 
   
 
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Issue Time Tracking
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            Worklog Id:     (was: 387469)
    Remaining Estimate: 0h
            Time Spent: 10m

> 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
>
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> 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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