[jira] [Commented] (HIVE-16688) Make sure Alter Table to set transaction=true acquires X lock

["Eugene Koifman (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-16688?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16282865#comment-16282865 ] 

Eugene Koifman commented on HIVE-16688:
---------------------------------------

this applies to converting to MM table which copies all existing files to a delta_x.  Need to make sure a parallel insert does write data to partition root that won't be copied

> Make sure Alter Table to set transaction=true acquires X lock
> -------------------------------------------------------------
>
>                 Key: HIVE-16688
>                 URL: https://issues.apache.org/jira/browse/HIVE-16688
>             Project: Hive
>          Issue Type: Sub-task
>          Components: Transactions
>    Affects Versions: 1.3.0
>            Reporter: Eugene Koifman
>            Assignee: Eugene Koifman
>            Priority: Critical
>             Fix For: 3.0.0
>
>         Attachments: HIVE-16688.01.patch, HIVE-16688.02.patch
>
>
> suppose we have non-acid table with some data
> An insert op starts (long running)  (with hive.txn.strict.locking.mode=false this takes shared lock)
> An alter table runs to add (transactional=true)
> An update is run which will read the list of "original" files and assign IDs on the fly which are written to a delta file.
> The long running insert completes.
> Another update is run which now sees a different set of "original" files and will (most likely) assign different IDs.
> Need to make sure to mutex this
> To clarify: The X lock is acquired for "An alter table runs to add (transactional=true)"



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