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https://issues.apache.org/jira/browse/HIVE-21267?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jesus Camacho Rodriguez reassigned HIVE-21267:
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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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