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From Dag.Wan...@Sun.COM (Dag H. Wanvik)
Subject Re: query works on 10.2, feezes with high CPU on 10.3 and above
Date Tue, 15 Jun 2010 00:20:46 GMT
Christopher Chisholm <christopher.chisholm@syamsoftware.com> writes:
> I have recently upgraded to a derby  This same query no
> longer completes.  Instead, it seems the CPU usage of the process that
> runs the query shoots up to 50-80%, and never completes (i've left it
> for hours).  Any ideas why?

It could be that the optimizer has changed and is now picking a bad
query plan, so the query takes a very long time to complete.

If you can run with -Dderby.language.logQueryPlan=true and attach the
query plans you see (in derby.log) for 10.2 and 10.6, we could compare
and see what changed if anything. 
Try to make the slow query complete by letting run overnight ;-)

See also http://wiki.apache.org/db-derby/PerformanceDiagnosisTips

If you can produce a sample database which shows the slowdown and
enclose that to a Derby JIRA issue, that would be even better and
allow us to speed ut detection of the issue.

For how to file  a Derby bug report, cf.


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