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From "Matt Martin (JIRA)" <>
Subject [jira] [Created] (HIVE-3509) Exclusive locks are not acquired when using dynamic partitions
Date Thu, 27 Sep 2012 17:06:08 GMT
Matt Martin created HIVE-3509:

             Summary: Exclusive locks are not acquired when using dynamic partitions
                 Key: HIVE-3509
             Project: Hive
          Issue Type: Bug
          Components: Locking
    Affects Versions: 0.9.0
            Reporter: Matt Martin

If locking is enabled, the acquireReadWriteLocks() method in org.apache.hadoop.hive.ql.Driver
iterates through all of the input and output entities of the query plan and attempts to acquire
the appropriate locks.  In general, it should acquire SHARED locks for all of the input entities
and exclusive locks for all of the output entities (see the Hive wiki page on [locking|]
for more detailed information).

When the query involves dynamic partitions, the situation is a little more subtle.  As the
Hive wiki notes (see previous link):

in some cases, the list of objects may not be known - for eg. in case of dynamic partitions,
the list of partitions being modified is not known at compile time - so, the list is generated
conservatively. Since the number of partitions may not be known, an exclusive lock is taken
on the table, or the prefix that is known.

After [HIVE-1781|], the observed behavior is
no longer consistent with the behavior described above.  [HIVE-1781|]
appears to have altered the logic so that SHARED locks are acquired instead of EXCLUSIVE locks
whenever the query involves dynamic partitions.

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