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https://issues.apache.org/jira/browse/HIVE-3509?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13626285#comment-13626285
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Namit Jain commented on HIVE-3509:
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comments
> Exclusive locks are not acquired when using dynamic partitions
> --------------------------------------------------------------
>
> Key: HIVE-3509
> URL: https://issues.apache.org/jira/browse/HIVE-3509
> Project: Hive
> Issue Type: Bug
> Components: Locking
> Affects Versions: 0.9.0
> Reporter: Matt Martin
> Assignee: Matt Martin
> Attachments: HIVE-3509.1.patch.txt, HIVE-3509.D10065.1.patch
>
>
> 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|https://cwiki.apache.org/confluence/display/Hive/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):
> {quote}
> 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.
> {quote}
> After [HIVE-1781|https://issues.apache.org/jira/browse/HIVE-1781], the
> observed behavior is no longer consistent with the behavior described above.
> [HIVE-1781|https://issues.apache.org/jira/browse/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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