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From "wangmeng (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-10971) count(*) with count(distinct) gives wrong results when hive.groupby.skewindata=true
Date Tue, 09 Jun 2015 09:58:00 GMT

     [ https://issues.apache.org/jira/browse/HIVE-10971?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

wangmeng updated HIVE-10971:
----------------------------
    Component/s:     (was: Hive)
                 Logical Optimizer

> 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
>
> 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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