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From "Namit Jain (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HIVE-757) Don't send constants from mapper to reducer for Group By queries
Date Thu, 17 Dec 2009 23:52:18 GMT

     [ https://issues.apache.org/jira/browse/HIVE-757?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Namit Jain updated HIVE-757:
----------------------------

    Fix Version/s:     (was: 0.5.0)

> Don't send constants from mapper to reducer for Group By queries
> ----------------------------------------------------------------
>
>                 Key: HIVE-757
>                 URL: https://issues.apache.org/jira/browse/HIVE-757
>             Project: Hadoop Hive
>          Issue Type: Improvement
>            Reporter: Zheng Shao
>            Assignee: Zheng Shao
>
> If an aggregation function takes a constant expression, we are still sending it from
mapper to reducer, but it's not necessary since we can compute the constants on the reducer
side.
> This will be useful for some UDAF that have configuration parameters:
> {code}
> SELECT pageid, logistic_regression("-t 1.0 -b 2.0", col1, col2, col3) FROM mytable GROUP
BY pageid;
> {code}

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