maria-developers team mailing list archive

[Kazuhiko Shiozaki <kazuhiko@xxxxxxxxxx>]

Hi Kristian,

On 21/02/2013 13:31, Kristian Nielsen wrote:
>> I tried setting SERIALIZABLE isolation globally and confirmed that
>> (much) more deadlocks happened. But unfortunately "Duplicate entry"
>> error still happens.
>>
>>            @@GLOBAL.tx_isolation: SERIALIZABLE
>>                   @@tx_isolation: SERIALIZABLE
>> @@innodb_locks_unsafe_for_binlog: 1
> 
> I don't know.
> 
> I am not sure what the semantics is for setting innodb_locks_unsafe_for_binlog
> at the same time as SERIALIZABLE. They seem kind of contradictory to me.
> 
> Do you still get the deadlocks if you use SERIALIZABLE without
> innodb_locks_unsafe_for_binlog?

Sorry for late reply. Yes still deadlocks happen often with using
SERIALIZABLE without innodb_locks_unsafe_for_binlog.

Considering our use cases, it seems that using REPEATABLE-READ with
innodb_locks_unsafe_for_binlog is faster than other options we tried,
even though our application should handle "Duplicate entry" well to
retry transactions, because this way has much less deadlocks.

> By the way, you do not need to set SERIALIZABLE globally. Why not set it only
> for that particular kind of transaction?

Yes I know. I set it globally only because it was the easiest way
without modifying the application at all...

Regards,
-- 
Kazuhiko Shiozaki, Nexedi SA Senior Consultant
Nexedi: Consulting and Development of Free / Open Source Software
http://www.nexedi.com/
ERP5: Full Featured High End Open Source ERP
http://www.erp5.com/