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From Nikolaos Paraschou <nipar...@gmail.com>
Subject Re: How to stop a long running query?
Date Fri, 20 Aug 2010 05:37:40 GMT
Thank you for your replies. I'll try out your suggestions. It seems, though,
it is a pretty hard task...

Regards,
Nikos

2010/8/19 Chris Poulsen <mailinglist@nesluop.dk>

> Hi,
>
> I've played around with query cancellation a couple of years ago (on Oracle
> btw), the strategy I found to be least intrusive was to wrap the JDBC
> connection/statements in my own Connection/*Statement classes and let
> statements register themselves somewhere accessible from other threads on
> creation and unregister on .close() before delegating to the inner instance.
>
> How you glue in the wrapped JDBC objects depends on your setup - you could
> create your own wrapping Driver or DataSource/DataSourceFactory.
>
> On my part it was an attempt to isolate the query cancellation stuff from
> an old webapp framework in order to be able to eliminate lots of home rolled
> jdbc/transaction handling and make it easier to integrate things like spring
> and cayenne, while maintaining the original feature-set (which included
> query cancellation). In the end it turned out that query cancellation wasn't
> really necessary and it was replaced by a fixed transaction timeout instead.
> (Simple cancellation was a breeze, but allowing the user to choose whether
> he would cancel or force a long-running query turned out to be a mess in our
> case)
>
> Hth!
>
> --
> Chris
>
>
>
> On 18-08-2010 21:54, Nikolaos Paraschou wrote:
>
>> Hello,
>>
>> I have written a small application in java that interacts with db2 using
>> apache cayenne.
>> The application sends a long running query to the db2 server and awaits
>> response. The query starts executing from within SwingWorker's
>> doInBackground() method. During the query's execution, a cancel button
>> appears allowing the user to cancel the operation. When clicked,
>> SwingWorker's cancel() is called and everything seems to work fine
>> regarding
>> java code. The SwingWorker thread is canceled (I can confirm that). But,
>> unfortunately, the other thread running the query doesn't stop (or perhaps
>> it stops but the query is already being processed by db2 until finished).
>>
>> Is there any way to stop the query using cayenne specific methods? I tried
>> to create a new DataContext and bind it to the running thread (the
>> following
>> code is executed inside doInBackground():
>>
>> BaseContext.bindThreadObjectContext(DataContext.createDataContext());
>> ObjectContext oc = BaseContext.getThreadObjectContext();
>>
>> return oc.performQuery(longRunQuery);
>>
>> No success.
>>
>> Thank you,
>> Nikos
>>
>>
>

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