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https://issues.apache.org/jira/browse/HIVE-3302?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kevin Wilfong updated HIVE-3302:
--------------------------------

    Status: Patch Available  (was: Open)
    
> Race condition in query plan for merging at the end of a query
> --------------------------------------------------------------
>
>                 Key: HIVE-3302
>                 URL: https://issues.apache.org/jira/browse/HIVE-3302
>             Project: Hive
>          Issue Type: Bug
>          Components: Query Processor
>    Affects Versions: 0.10.0
>            Reporter: Kevin Wilfong
>            Assignee: Kevin Wilfong
>            Priority: Critical
>         Attachments: HIVE-3302.1.patch.txt
>
>
> In the query plan that's used to merge files at the end of a query, the 
> dependency tree looks something like:
>                    MoveTask(1)
>                   /           \
> ...ConditionalTask             MoveTask(2)...
>                   \           /
>                    MergeTask
> Here MoveTask(1) moves the partition data to a temporary location, and 
> MoveTask(2) moves it to the final location.
> However if there are dynamic partitions generated and some of these 
> partitions are merged and others are moved, the dependency tree is changed at 
> runtime to:
> ...ConditionalTask           MoveTask(2)...
>                   \         /
>                    MergeTask
>                             \
>                              MoveTask(1)
> This produces a race condition between the two MoveTasks where if MoveTask(2) 
> runs before MoveTask(1) the partitions moved by MoveTask(1) will get moved to 
> an intermediate location and never moved to the final location.  In this case 
> those partitions are quietly lost.

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