hive-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Kevin Wilfong (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-3302) Race condition in query plan for merging at the end of a query
Date Thu, 26 Jul 2012 00:49:33 GMT
Kevin Wilfong created HIVE-3302:
-----------------------------------

             Summary: 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


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.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira

        

Mime
View raw message