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https://issues.apache.org/jira/browse/HIVE-8558?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14180060#comment-14180060
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Ashutosh Chauhan commented on HIVE-8558:
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[~vikram.dixit] ok for 0.14?
> CBO: enable n-way joins after CBO join reordering
> -------------------------------------------------
>
> Key: HIVE-8558
> URL: https://issues.apache.org/jira/browse/HIVE-8558
> Project: Hive
> Issue Type: Bug
> Reporter: Harish Butani
> Assignee: Harish Butani
> Attachments: HIVE-8558.1.patch
>
>
> With CBO, we disable n-way joins. But for consecutive tables we can safely
> collapse into n-way joins. For e.g this is safe to collapse:
> {code}
> select p1.p_name, p2.p_name, p3.p_name from part p1 join part p2 on p1.p_name
> = p2.p_name join part p3 on p3.p_name = p1.p_name;
> {code}
> whereas, we shouldn't reorder in this case:
> {code}
> select p1.p_name, p2.p_name, p3.p_name
> from part p1 join part p2 on p1.p_name = p2.p_name join part p3 on p3.p_size
> = p1.p_size and p3.p_size = p2.p_size join part p4 on p1.p_name = p4.p_name;
> {code}
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