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https://issues.apache.org/jira/browse/HIVE-4241?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13629237#comment-13629237
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Gang Tim Liu commented on HIVE-4241:
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+1
> optimize hive.enforce.sorting and hive.enforce bucketing join
> -------------------------------------------------------------
>
> Key: HIVE-4241
> URL: https://issues.apache.org/jira/browse/HIVE-4241
> Project: Hive
> Issue Type: Improvement
> Components: Query Processor
> Reporter: Namit Jain
> Assignee: Namit Jain
> Attachments: hive.4241.1.patch, hive.4241.1.patch-nohcat,
> hive.4241.2.patch-nohcat
>
>
> Consider the following scenario:
> T1: sorted and bucketed by key into 2 buckets
> T2: sorted and bucketed by key into 2 buckets
> T3: sorted and bucketed by key into 2 buckets
> set hive.enforce.sorting=true;
> set hive.enforce.bucketing=true;
> insert overwrite table T3
> select .. from T1 join T2 on T1.key = T2.key;
> Since T1, T2 and T3 are sorted/bucketed by the join, and the above join is
> being performed as a sort-merge join, T3 should be bucketed/sorted without
> the need for an extra reducer.
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