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From wfalby <wfa...@hotmail.com>
Subject Re: Row Locking
Date Mon, 04 May 2009 11:34:11 GMT



Kristian Waagan-4 wrote:
> 
> wfalby wrote:
>> My application processes events. These events are sent to registered
>> users.
>> These events can be deleted when they reach a certain age. There is a
>> thread
>> to send events to registered users and there is another thread to delete
>> old
>> events. The thread sending an event should lock it from the thread that
>> deletes old events. Each thread uses its own connection to the database.
>> In
>> the sending thread, I've tried using a SELECT ... FOR UPDATE and setting
>> the
>> ResultSet.CONCUR_UPDATABLE on the prepare statement. In both cases, the
>> thread that deletes events deleted the event being held by the sending
>> thread. The default isolation level and autocommit options are used.
>>   
> 
> Hi Walter,
> 
> If you're using the read committed isolation level, I think you need to 
> use SELECT ... FOR UPDATE WITH RS.
> Which behavior do you see if you do that?
> 
> I think Derby treats SELECT ... FOR UPDATE a bit differently than some 
> other database systems, and I also believe there is at least one Jira 
> [1] issue logged for changing the behavior.
> 
> 
> Regards,
> -- 
> Kristian
> 
> [1] https://issues.apache.org/jira/browse/DERBY
>> Thanks in advance...Walter
>>   
> 
> 
> 

Kristian:

Thanks for the info. I tried your suggestion, but all rows are deleted. I'll
check the Jira issue to see if it fits my situation.

Walter
-- 
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