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From "Jason Dere (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-17482) External LLAP client: acquire locks for tables queried directly by LLAP
Date Tue, 12 Sep 2017 17:39:00 GMT

    [ https://issues.apache.org/jira/browse/HIVE-17482?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16163337#comment-16163337
] 

Jason Dere commented on HIVE-17482:
-----------------------------------

Attempting to release locks seems to be valid, as this is also done during Driver.rollback()
which can be called during a failed compilation. If there are no locks held the cleanup seems
to not do much.
The alternative would be to skip the cleanup object in the case that acquiring the lock fails
- if you think that is better I can change it to do that.

> External LLAP client: acquire locks for tables queried directly by LLAP
> -----------------------------------------------------------------------
>
>                 Key: HIVE-17482
>                 URL: https://issues.apache.org/jira/browse/HIVE-17482
>             Project: Hive
>          Issue Type: Sub-task
>          Components: llap
>            Reporter: Jason Dere
>            Assignee: Jason Dere
>         Attachments: HIVE-17482.1.patch
>
>
> When using the LLAP external client with simple queries (filter/project of single table),
the appropriate locks should be taken on the table being read like they are for normal Hive
queries. This is important in the case of transactional tables being queried, since the compactor
relies on the presence of table locks to determine whether it can safely delete old versions
of compacted files without affecting currently running queries.
> This does not have to happen in the complex query case, since a query is used (with the
appropriate locking mechanisms) to create/populate the temp table holding the results to the
complex query.



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