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https://issues.apache.org/jira/browse/HIVE-24234?focusedWorklogId=499747&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-499747
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ASF GitHub Bot logged work on HIVE-24234:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 13/Oct/20 00:11
Start Date: 13/Oct/20 00:11
Worklog Time Spent: 10m
Work Description: ashutoshc commented on pull request #1560:
URL: https://github.com/apache/hive/pull/1560#issuecomment-707408314
+1 LGTM
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Issue Time Tracking
-------------------
Worklog Id: (was: 499747)
Time Spent: 20m (was: 10m)
> Improve checkHashModeEfficiency in VectorGroupByOperator
> --------------------------------------------------------
>
> Key: HIVE-24234
> URL: https://issues.apache.org/jira/browse/HIVE-24234
> Project: Hive
> Issue Type: Improvement
> Reporter: Rajesh Balamohan
> Assignee: Rajesh Balamohan
> Priority: Major
> Labels: pull-request-available
> Attachments: HIVE-24234.wip.patch
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Currently, {{VectorGroupByOperator::checkHashModeEfficiency}} compares the
> number of entries with the number input records that have been processed. For
> grouping sets, it accounts for grouping set length as well.
> Issue is that, the condition becomes invalid after processing large number of
> input records. This prevents the system from switching over to streaming
> mode.
> e.g Assume 500,000 input records processed, with 9 grouping sets, with
> 100,000 entries in hashtable. Hashtable would never cross 4,500,0000 entries
> as the max size itself is 1M by default.
> It would be good to compare the input records (adjusted for grouping sets)
> with number of output records (along with size of hashtable size) to
> determine hashing or streaming mode.
> E.g Q67.
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