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https://issues.apache.org/jira/browse/DERBY-5073?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13004573#comment-13004573
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Knut Anders Hatlen commented on DERBY-5073:
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Hi Karl,
Yes, that looks like a cycle, and Derby should have been able to detect it and
throw an SQLException.
> Derby deadlocks without recourse on simultaneous correlated subqueries
> ----------------------------------------------------------------------
>
> Key: DERBY-5073
> URL: https://issues.apache.org/jira/browse/DERBY-5073
> Project: Derby
> Issue Type: Bug
> Reporter: Karl Wright
>
> When the following two queries are run against tables that contain the
> necessary fields, using multiple threads, Derby deadlocks and none of the
> queries ever returns. Derby apparently detects no deadlock condition, either.
> SELECT t0.* FROM jobqueue t0 WHERE EXISTS(SELECT 'x' FROM carrydown t1 WHERE
> t1.parentidhash IN (?) AND t1.childidhash=t0.dochash AND t0.jobid=t1.jobid)
> AND t0.jobid=?
> SELECT t0.* FROM jobqueue t0 WHERE EXISTS(SELECT 'x' FROM carrydown t1 WHERE
> t1.parentidhash IN (?) AND t1.childidhash=t0.dochash AND t0.jobid=t1.jobid
> AND t1.newField=?) AND t0.jobid=?
> This code comes from Apache ManifoldCF, and has occurred when there are five
> or more threads trying to execute these two queries at the same time.
> Originally we found this on 10.5.3.0. It was hoped that 10.7.1.1 would fix
> the problem, but it hasn't.
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