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https://issues.apache.org/jira/browse/SENTRY-1486?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15573339#comment-15573339
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Alexander Kolbasov commented on SENTRY-1486:
--------------------------------------------

In Oracle classification "serializable" is the "repeatable reads" in MySQL. I 
looked at the DB drivers in Datanucleus - they assume that Oracle support 
repeatable reads, so they don't distinguish. They have a logic to move to a 
higher level if a specific one isn't supported, so it would work correctly if 
they don't mark repeatable-read as supported by Oracle. This means that we 
can't rely on DN to do the right thing and should figure out how to make a 
different setting for Oracle.

> Sentry should use repeatable-read consistency level
> ---------------------------------------------------
>
>                 Key: SENTRY-1486
>                 URL: https://issues.apache.org/jira/browse/SENTRY-1486
>             Project: Sentry
>          Issue Type: Bug
>          Components: Sentry
>    Affects Versions: 1.7.0, sentry-ha-redesign
>            Reporter: Alexander Kolbasov
>            Assignee: Alexander Kolbasov
>             Fix For: 1.8.0
>
>         Attachments: SENTRY-1486.001.patch, SENTRY-1486.002.patch
>
>
> Currently Sentry uses the "read-committed" consistency level which is the 
> default for the Datanucleus JDO library. This causes potential problems since 
> the state visible to each transaction can actually see updates from another 
> transactions, so it is very difficult to reason about any code that reads 
> multiple pieces of data.
> Instead it should use repeatable read" consistency which guarantees that any 
> transaction only sees the state at the beginning of a transaction plus any 
> updates done within a transaction.



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