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https://issues.apache.org/jira/browse/HIVE-26009?focusedWorklogId=768207&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-768207
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ASF GitHub Bot logged work on HIVE-26009:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 09/May/22 22:10
Start Date: 09/May/22 22:10
Worklog Time Spent: 10m
Work Description: simhadri-g closed pull request #3224: HIVE-26009:
Determine number of buckets for implicitly bucketed ACIDv…
URL: https://github.com/apache/hive/pull/3224
Issue Time Tracking
-------------------
Worklog Id: (was: 768207)
Time Spent: 20m (was: 10m)
> Determine number of buckets for implicitly bucketed ACIDv2 tables
> ------------------------------------------------------------------
>
> Key: HIVE-26009
> URL: https://issues.apache.org/jira/browse/HIVE-26009
> Project: Hive
> Issue Type: Improvement
> Reporter: Simhadri G
> Assignee: Simhadri G
> Priority: Major
> Labels: pull-request-available
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Hive tries to set number of reducers equal to number of buckets here:
> [https://github.com/apache/hive/blob/9857c4e584384f7b0a49c34bc2bdf876c2ea1503/ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java#L6958]
>
>
> The numberOfBuckets for implicitly bucketed tables is set to -1 by default.
> When this is the case, it is left to hive to estimate the number of reducers
> required the job, based on job input, and configuration parameters.
> [https://github.com/apache/hive/blob/9857c4e584384f7b0a49c34bc2bdf876c2ea1503/ql/src/java/org/apache/hadoop/hive/ql/exec/Utilities.java#L3369]
>
> This estimate is not optimal in all cases. In the worst case, it case result
> in a single reducer being launched , which can lead to a significant
> bottleneck in performance .
>
> Ideally, the number of reducers launched should equal to number of buckets,
> which is the case for explicitly bucketed tables.
>
>
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