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https://issues.apache.org/jira/browse/HIVE-22925?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Attila Magyar updated HIVE-22925:
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Description:
In certain cases the TopNKey filter might work in an inefficient way and adds
extra CPU overhead. For example if the rows are coming in an descending order
but the filter wants the top N smallest elements the filter will forward
everything.
Inefficient should be detected in runtime so that the filter can be disabled of
the ration between forwarder_rows/total_rows is too high.
was:
In certain cases the TopNKey filter might work in an inefficient way and adds
extra CPU overhead. For example if the rows are coming in an ascending order
but the filter wants the top N smallest elements the filter will forward
everything.
Inefficient should be detected in runtime so that the filter can be disabled of
the ration between forwarder_rows/total_rows is too high.
> Implement TopNKeyFilter efficiency check
> ----------------------------------------
>
> Key: HIVE-22925
> URL: https://issues.apache.org/jira/browse/HIVE-22925
> Project: Hive
> Issue Type: Bug
> Components: Hive
> Reporter: Attila Magyar
> Assignee: Attila Magyar
> Priority: Major
> Fix For: 4.0.0
>
> Attachments: HIVE-22925.1.patch
>
>
> In certain cases the TopNKey filter might work in an inefficient way and adds
> extra CPU overhead. For example if the rows are coming in an descending order
> but the filter wants the top N smallest elements the filter will forward
> everything.
> Inefficient should be detected in runtime so that the filter can be disabled
> of the ration between forwarder_rows/total_rows is too high.
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