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From "Denys Kuzmenko (Jira)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-23349) ACID: Concurrent MERGE INSERT operations produce duplicates
Date Thu, 07 May 2020 13:21:00 GMT

     [ https://issues.apache.org/jira/browse/HIVE-23349?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Denys Kuzmenko updated HIVE-23349:
----------------------------------
    Attachment:     (was: HIVE-23349.5.patch)

> ACID: Concurrent MERGE INSERT operations produce duplicates
> -----------------------------------------------------------
>
>                 Key: HIVE-23349
>                 URL: https://issues.apache.org/jira/browse/HIVE-23349
>             Project: Hive
>          Issue Type: Bug
>          Components: Transactions
>            Reporter: Denys Kuzmenko
>            Assignee: Denys Kuzmenko
>            Priority: Major
>         Attachments: HIVE-23349.1.patch, HIVE-23349.2.patch, HIVE-23349.3.patch, HIVE-23349.4.patch,
HIVE-23349.5.patch
>
>
> 2 concurrent MERGE INSERT operations generate duplicates due to lack of locking. 
> MERGE INSERT is treated as regular INSERT, it acquires SHARED_READ lock that doesn't
prevent other INSERTs. We should use EXCLUSIVE lock here or EXCL_WRITE if hive.txn.write.xlock=false;
> {code}
> create table target (a int, b int) stored as orc TBLPROPERTIES ('transactional'='true')");
> insert into target values (1,2), (3,4)
> create table source (a int, b int)
> {code}
> execute in parallel:
> {code}
> insert into source values (5,6), (7,8)
> {code}



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