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https://issues.apache.org/jira/browse/HIVE-23365?focusedWorklogId=439774&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-439774
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ASF GitHub Bot logged work on HIVE-23365:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 01/Jun/20 22:26
Start Date: 01/Jun/20 22:26
Worklog Time Spent: 10m
Work Description: asfgit closed pull request #1035:
URL: https://github.com/apache/hive/pull/1035
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Issue Time Tracking
-------------------
Worklog Id: (was: 439774)
Time Spent: 1h (was: 50m)
> Put RS deduplication optimization under cost based decision
> -----------------------------------------------------------
>
> Key: HIVE-23365
> URL: https://issues.apache.org/jira/browse/HIVE-23365
> Project: Hive
> Issue Type: Improvement
> Components: Physical Optimizer
> Reporter: Jesus Camacho Rodriguez
> Assignee: Stamatis Zampetakis
> Priority: Major
> Labels: pull-request-available
> Attachments: HIVE-23365.01.patch, HIVE-23365.02.patch,
> HIVE-23365.03.patch, HIVE-23365.04.patch, HIVE-23365.05.patch
>
> Time Spent: 1h
> Remaining Estimate: 0h
>
> Currently, RS deduplication is always executed whenever it is semantically
> correct. However, it could be beneficial to leave both RS operators in the
> plan, e.g., if the NDV of the second RS is very low. Thus, we would like this
> decision to be cost-based. We could use a simple heuristic that would work
> fine for most of the cases without introducing regressions for existing
> cases, e.g., if NDV for partition column is less than estimated parallelism
> in the second RS, do not execute deduplication.
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