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From "Pengcheng Xiong (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-16797) Enhance HiveFilterSetOpTransposeRule to remove union branches
Date Sat, 10 Jun 2017 21:56:18 GMT

     [ https://issues.apache.org/jira/browse/HIVE-16797?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Pengcheng Xiong updated HIVE-16797:
-----------------------------------
    Status: Open  (was: Patch Available)

> Enhance HiveFilterSetOpTransposeRule to remove union branches
> -------------------------------------------------------------
>
>                 Key: HIVE-16797
>                 URL: https://issues.apache.org/jira/browse/HIVE-16797
>             Project: Hive
>          Issue Type: Sub-task
>            Reporter: Pengcheng Xiong
>            Assignee: Pengcheng Xiong
>         Attachments: HIVE-16797.01.patch, HIVE-16797.02.patch, HIVE-16797.03.patch
>
>
> in query4.q, we can see that it creates a CTE with union all of 3 branches. Then it is
going to do a 3 way self-join of the CTE with predicates. The predicates actually specifies
only one of the branch in CTE to participate in the join. Thus, in some cases, e.g.,
> {code}
>                /- filter(false) -----TS0 
> union all  - filter(false) -----TS1
>                \-----TS2
> {code}
> we can cut the branches of TS0 and TS1. The union becomes only TS2.



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