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From "Jesus Camacho Rodriguez (Jira)" <j...@apache.org>
Subject [jira] [Assigned] (HIVE-21267) Extend HiveRelColumnsAlignment to reorder group-by and join keys on decreasing NDV automatically
Date Thu, 19 Sep 2019 18:28:00 GMT

     [ https://issues.apache.org/jira/browse/HIVE-21267?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jesus Camacho Rodriguez reassigned HIVE-21267:
----------------------------------------------

    Assignee: John Sherman

> Extend HiveRelColumnsAlignment to reorder group-by and join keys on decreasing NDV automatically
> ------------------------------------------------------------------------------------------------
>
>                 Key: HIVE-21267
>                 URL: https://issues.apache.org/jira/browse/HIVE-21267
>             Project: Hive
>          Issue Type: Improvement
>          Components: CBO
>            Reporter: Jesus Camacho Rodriguez
>            Assignee: John Sherman
>            Priority: Major
>              Labels: newbie++
>
> {{HiveRelColumnsAlignment}} was introduced to align the order of columns in join, group-by,
and order-by operators in the plan pipeline, trying to increase the effect of ReduceDeduplication
and thus reducing data shuffle.
> The optimization could be extended to reorder group-by and join keys on decreasing NDV,
which would accelerate comparison runtime.



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