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From "Zoltan Haindrich (Jira)" <>
Subject [jira] [Commented] (HIVE-22893) Enhance data size estimation for fields computed by UDFs
Date Fri, 13 Mar 2020 12:50:00 GMT


Zoltan Haindrich commented on HIVE-22893:

this patch have created a file w/o the asf header;
I've pushed an addendum to fix it

> Enhance data size estimation for fields computed by UDFs
> --------------------------------------------------------
>                 Key: HIVE-22893
>                 URL:
>             Project: Hive
>          Issue Type: Improvement
>          Components: Statistics
>            Reporter: Zoltan Haindrich
>            Assignee: Zoltan Haindrich
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 4.0.0
>         Attachments: HIVE-22893.01.patch, HIVE-22893.02.patch, HIVE-22893.03.patch, HIVE-22893.04.patch,
HIVE-22893.05.patch, HIVE-22893.06.patch, HIVE-22893.07.patch, HIVE-22893.08.patch, HIVE-22893.09.patch,
HIVE-22893.10.patch, HIVE-22893.11.patch, HIVE-22893.12.patch, HIVE-22893.13.patch, HIVE-22893.14.patch
>          Time Spent: 2h
>  Remaining Estimate: 0h
> Right now if we have columnstat on a column ; 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 improvement 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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