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https://issues.apache.org/jira/browse/HIVE-20983?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16930863#comment-16930863
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Hive QA commented on HIVE-20983:
--------------------------------
Here are the results of testing the latest attachment:
https://issues.apache.org/jira/secure/attachment/12980424/HIVE-20983.5.patch
{color:green}SUCCESS:{color} +1 due to 7 test(s) being added or modified.
{color:green}SUCCESS:{color} +1 due to 16760 tests passed
Test results:
https://builds.apache.org/job/PreCommit-HIVE-Build/18618/testReport
Console output: https://builds.apache.org/job/PreCommit-HIVE-Build/18618/console
Test logs: http://104.198.109.242/logs/PreCommit-HIVE-Build-18618/
Messages:
{noformat}
Executing org.apache.hive.ptest.execution.TestCheckPhase
Executing org.apache.hive.ptest.execution.PrepPhase
Executing org.apache.hive.ptest.execution.YetusPhase
Executing org.apache.hive.ptest.execution.ExecutionPhase
Executing org.apache.hive.ptest.execution.ReportingPhase
{noformat}
This message is automatically generated.
ATTACHMENT ID: 12980424 - PreCommit-HIVE-Build
> Vectorization: Scale up small hashtables, when collisions are detected
> ----------------------------------------------------------------------
>
> Key: HIVE-20983
> URL: https://issues.apache.org/jira/browse/HIVE-20983
> Project: Hive
> Issue Type: Bug
> Reporter: Gopal V
> Assignee: Mustafa Iman
> Priority: Major
> Labels: pull-request-available
> Attachments: HIVE-20983.1.patch, HIVE-20983.2.patch,
> HIVE-20983.3.patch, HIVE-20983.4.patch, HIVE-20983.5.patch
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Hive's hashtable estimates are getting better with HyperLogLog stats in
> place, but an accurate estimate does not always result in a low number of
> collisions.
> The hashtables which contain a very small number of items tend to lose their
> O(1) lookup performance where there are collisions. Since collisions are easy
> to detect within the fast hashtable implementation, a rehashing to a higher
> size will help these small hashtables avoid collisions and go back to O(1)
> perf.
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