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From "Wei Zheng (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-12996) Temp tables shouldn't be locked
Date Tue, 10 May 2016 18:26:13 GMT

    [ https://issues.apache.org/jira/browse/HIVE-12996?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15278634#comment-15278634
] 

Wei Zheng commented on HIVE-12996:
----------------------------------

Ignore the above comment. That was for a different ticket ^_^

> Temp tables shouldn't be locked
> -------------------------------
>
>                 Key: HIVE-12996
>                 URL: https://issues.apache.org/jira/browse/HIVE-12996
>             Project: Hive
>          Issue Type: Bug
>          Components: Transactions
>    Affects Versions: 2.0.0
>            Reporter: Wei Zheng
>            Assignee: Wei Zheng
>         Attachments: HIVE-12996.1.patch, HIVE-12996.2.patch
>
>
> Internally, INSERT INTO ... VALUES statements use temp table to accomplish its functionality.
But temp tables shouldn't be stored in the metastore tables for ACID, because they are by
definition only visible inside the session that created them, and we don't allow multiple
threads inside a session. If a temp table is used in a query, it should be ignored by lock
manager.
> {code}
> mysql> select * from COMPLETED_TXN_COMPONENTS;
> +-----------+--------------+-----------------------+------------------+
> | CTC_TXNID | CTC_DATABASE | CTC_TABLE             | CTC_PARTITION    |
> +-----------+--------------+-----------------------+------------------+
> |         1 | acid         | t1                    | NULL             |
> |         1 | acid         | values__tmp__table__1 | NULL             |
> |         2 | acid         | t1                    | NULL             |
> |         2 | acid         | values__tmp__table__2 | NULL             |
> |         3 | acid         | values__tmp__table__3 | NULL             |
> |         3 | acid         | t1                    | NULL             |
> |         4 | acid         | values__tmp__table__1 | NULL             |
> |         4 | acid         | t2p                   | ds=today         |
> |         5 | acid         | values__tmp__table__1 | NULL             |
> |         5 | acid         | t3p                   | ds=today/hour=12 |
> +-----------+--------------+-----------------------+------------------+
> {code}



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