> On Jan. 21, 2016, 12:28 p.m., John Sirois wrote:
> > IIUC the MVCC capabilities in 1.4+ should prevent table locks on all but 
> > DDL stuff.
> 
> John Sirois wrote:
>     Hmm - more to the story: "If MVCC is enabled, changing the lock mode 
> (LOCK_MODE) has no effect." ... Maybe turning on MVCC is worth some perf 
> tests or have you already been down that road?
> 
> Maxim Khutornenko wrote:
>     I suggest a cautios approach to enabling MVCC as our previous experience 
> showed unacceptable performance with any meaningful amounts of data.

Bigger caution for me is that MVCC is considered beta in H2.


> On Jan. 21, 2016, 12:28 p.m., John Sirois wrote:
> > src/main/java/org/apache/aurora/scheduler/storage/db/DbModule.java, line 115
> > <https://reviews.apache.org/r/42613/diff/1/?file=1204582#file1204582line115>
> >
> >     Please fix the comment and add a pointer to 
> > http://www.h2database.com/html/advanced.html?highlight=LOCK_MODE&search=LOCK#transaction_isolation
> >  since "3" is so cryptic and folks - like me just now - will want to double 
> > check.

Agreed, fixed.


- Bill


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On Jan. 21, 2016, 12:25 p.m., Bill Farner wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/42613/
> -----------------------------------------------------------
> 
> (Updated Jan. 21, 2016, 12:25 p.m.)
> 
> 
> Review request for Aurora, John Sirois and Zameer Manji.
> 
> 
> Bugs: AURORA-1580
>     https://issues.apache.org/jira/browse/AURORA-1580
> 
> 
> Repository: aurora
> 
> 
> Description
> -------
> 
> Proposing this as the minimal fix for AURORA-1580.  I think it's wise, 
> however, to look towards the alternative approach i described in that ticket 
> for simplicity and performance gains.
> 
> I'd like to note that after this change, it will be important to treat 
> long-running transactions carefully.  It will be important to avoid 
> transactions block others by writing (locking a table) and subsequently doing 
> other lengthy work.
> 
> 
> Diffs
> -----
> 
>   src/main/java/org/apache/aurora/scheduler/storage/db/DbModule.java 
> 2b3ee7bf6f7801c140f921b25f78daf6d320098a 
>   src/main/resources/org/apache/aurora/scheduler/storage/db/TaskMapper.xml 
> e689cfeda39e1f065ed29c61a23376512df8f3aa 
>   
> src/test/java/org/apache/aurora/scheduler/storage/AbstractTaskStoreTest.java 
> 3dba286556ab6ea34b7fdd38508a164c902d9d17 
> 
> Diff: https://reviews.apache.org/r/42613/diff/
> 
> 
> Testing
> -------
> 
> 
> Thanks,
> 
> Bill Farner
> 
>

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