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https://issues.apache.org/jira/browse/HIVE-22893?focusedWorklogId=394300&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-394300
]
ASF GitHub Bot logged work on HIVE-22893:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 27/Feb/20 16:25
Start Date: 27/Feb/20 16:25
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
-------------------
Worklog Id: (was: 394300)
Time Spent: 2h (was: 1h 50m)
> 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, 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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