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Posted to dev@hive.apache.org by "Zheng Shao (JIRA)" <ji...@apache.org> on 2009/08/15 03:24:14 UTC
[jira] Created: (HIVE-757) Don't send constants from mapper to
reducer for Group By queries
Don't send constants from mapper to reducer for Group By queries
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Key: HIVE-757
URL: https://issues.apache.org/jira/browse/HIVE-757
Project: Hadoop Hive
Issue Type: Improvement
Reporter: Zheng Shao
Assignee: Zheng Shao
Fix For: 0.5.0
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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[jira] Updated: (HIVE-757) Don't send constants from mapper to
reducer for Group By queries
Posted by "Namit Jain (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/HIVE-757?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Namit Jain updated HIVE-757:
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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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