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https://issues.apache.org/jira/browse/HIVE-19283?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Goun Na reassigned HIVE-19283:
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> Select count(distinct()) a couple of times stuck in last reducer
> ----------------------------------------------------------------
>
> Key: HIVE-19283
> URL: https://issues.apache.org/jira/browse/HIVE-19283
> Project: Hive
> Issue Type: Improvement
> Components: CBO, Logical Optimizer
> Affects Versions: 2.1.1
> Reporter: Goun Na
> Assignee: Ashutosh Chauhan
> Priority: Major
>
>
> Distinct count query performance is significantly improved due to HIVE-10568.
> {code:java}
> select count(distinct elevenst_id)
> from 11st.log_table
> where part_dt between '20180101' and '20180131'{code}
>
> However, some queries that contain several distinct counts are still slow. It
> starts with multiple mappers, but stuck in the last one reducer.
>
> {code:java}
> select
> count(distinct elevenst_id)
> , count(distinct member_id)
> , count(distinct user_id)
> , count(distinct action_id)
> , count(distinct other_id)
> from 11st.log_table
> where part_dt between '20180101' and '20180131'{code}
>
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