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From Kathey Marsden <kmarsdende...@sbcglobal.net>
Subject Re: Fw: Can it be that Derby (in-memory) is deadlocking on this query? (UPDATE)
Date Thu, 20 Jan 2011 21:21:17 GMT
On 1/20/2011 1:03 PM, Pavel Bortnovskiy wrote:
> the more I am working through this issue, the more I get convinced 
> that it's a Derby issue.
> When the select statement is modified slightly (not using joining of 
> tables on themselves, but rather using IN), then everything works 
> without a hiccup:
>
> SELECT
>     P1.ID ,
>     R1.description
>     P1.BOOK
>     P1.NOMINAL
>     P1.NOMINAL * R1.Factor
> FROM
>     P_TABLE P1,
>     R_TABLE R1
> WHERE
>     P1.IN_ID = R1.IN_ID  AND
>     R1.IN_ID in (
>       select
>               R2.IN_ID
>       from
>               P_TABLE P2,
>               R_TABLE R2
>       where
>               P2.IN_ID = R2.IN_ID AND
>               P2.NOMINAL <> 0  AND
>               R2.IType='X'
>       GROUP BY R2.IN_ID
>       HAVING COUNT(*) >1
>     )
>
>
> So, this leads me to believe that SELECT statements such as this 
> causes a problem within Derby:
>
> select
>     *
> from
> *TABLE* T1,
>      (
>          select <field> from *TABLE* T2
>      ) as M
> where
>     M.<field> = T1.<field>
>
I think it would be worthwile to file an issue in Jira while you work to 
get a reproduction that the community can work with.  Put as much 
information as you can in the Jira issue especially useful would be a 
thread dump even if the proprietary parts are edited out.   You might 
also want to set lock timeout and deadlock timeout low [1] so that you 
don't have to wait for those errors if they are occurring.

Generally the more information you can provide the better the community 
will be able to help. As for it being urgent, once you get a 
reproduction and confirm it as a Derby issue, I think that you will find 
the development community very supportive if you want to try to fix it 
yourself.

Thanks

Kathey
[1] http://db.apache.org/derby/docs/10.7/devguide/cdevconcepts16400.html

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