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From "Yin Huai (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-4927) When we merge two MapJoin MapRedTasks, the TableScanOperator of the second one should be removed
Date Wed, 24 Jul 2013 21:11:49 GMT

     [ https://issues.apache.org/jira/browse/HIVE-4927?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Yin Huai updated HIVE-4927:
---------------------------

    Status: Patch Available  (was: Open)
    
> When we merge two MapJoin MapRedTasks, the TableScanOperator of the second one should
be removed
> ------------------------------------------------------------------------------------------------
>
>                 Key: HIVE-4927
>                 URL: https://issues.apache.org/jira/browse/HIVE-4927
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Yin Huai
>            Assignee: Yin Huai
>         Attachments: HIVE-4927.1.patch
>
>
> {code}
> set hive.auto.convert.join=true;
> set hive.auto.convert.join.noconditionaltask=true;
> EXPLAIN
> SELECT x1.key AS key FROM src x1 JOIN src1 y1 ON (x1.key = y1.key) JOIN src1 y2 ON (x1.value
= y2.value) GROUP BY x1.key;
> {\code}
> We will get a NPE from MetadataOnlyOptimizer. The reason is that the operator tree of
the MapRedTask evaluating two MapJoins is 
> {code}
> TS1->MapJoin1->TS2->MapJoin2->...
> {\code}
> We should remove the TS2...

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