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https://issues.apache.org/jira/browse/HIVE-10971?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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wangmeng updated HIVE-10971:
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Attachment: (was: HIVE-10971.01.patch)
> count(*) with count(distinct) gives wrong results when
> hive.groupby.skewindata=true
> -----------------------------------------------------------------------------------
>
> Key: HIVE-10971
> URL: https://issues.apache.org/jira/browse/HIVE-10971
> Project: Hive
> Issue Type: Bug
> Components: Logical Optimizer
> Affects Versions: 1.2.0
> Reporter: wangmeng
> Assignee: wangmeng
> Attachments: HIVE-10971.01.patch
>
>
> When hive.groupby.skewindata=true, the following query based on TPC-H gives
> wrong results:
> {code}
> set hive.groupby.skewindata=true;
> select l_returnflag, count(*), count(distinct l_linestatus)
> from lineitem
> group by l_returnflag
> limit 10;
> {code}
> The query plan shows that it generates only one MapReduce job instead of two
> theoretically, which is dictated by hive.groupby.skewindata=true.
> The problem arises only when {noformat}count(*){noformat} and
> {noformat}count(distinct){noformat} exist together.
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