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Posted to issues@hive.apache.org by "ASF GitHub Bot (Jira)" <ji...@apache.org> on 2019/09/24 21:48:00 UTC
[jira] [Work logged] (HIVE-22239) Scale data size using column
value ranges
[ https://issues.apache.org/jira/browse/HIVE-22239?focusedWorklogId=317871&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-317871 ]
ASF GitHub Bot logged work on HIVE-22239:
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Author: ASF GitHub Bot
Created on: 24/Sep/19 21:47
Start Date: 24/Sep/19 21:47
Worklog Time Spent: 10m
Work Description: jcamachor commented on pull request #787: HIVE-22239
URL: https://github.com/apache/hive/pull/787
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Issue Time Tracking
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Worklog Id: (was: 317871)
Remaining Estimate: 0h
Time Spent: 10m
> Scale data size using column value ranges
> -----------------------------------------
>
> Key: HIVE-22239
> URL: https://issues.apache.org/jira/browse/HIVE-22239
> Project: Hive
> Issue Type: Improvement
> Components: Physical Optimizer
> Reporter: Jesus Camacho Rodriguez
> Assignee: Jesus Camacho Rodriguez
> Priority: Major
> Labels: pull-request-available
> Attachments: HIVE-22239.patch
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Currently, min/max values for columns are only used to determine whether a certain range filter falls out of range and thus filters all rows or none at all. If it does not, we just use a heuristic that the condition will filter 1/3 of the input rows. Instead of using that heuristic, we can use another one that assumes that data will be uniformly distributed across that range, and calculate the selectivity for the condition accordingly.
> This patch also includes the propagation of min/max column values from statistics to the optimizer for timestamp type.
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