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From Robert Zeigler <>
Subject Re: Performance question
Date Tue, 24 Jan 2012 20:39:50 GMT
Are you using query prefetching?


On Jan 24, 2012, at 1/2410:11 AM , Wernke zur Borg wrote:

> Dear list,
> I have another question. My application converts a huge MS Access 
> database to a set of XML files by traversing some really big tables with 
> Select queries and also querying related tables to collect the 
> information needed for the output. Performance is horribly bad, so I did 
> some profiling and found that it spends 75% of its CPU time in 
> org.apache.cayenne.access.ExternalTransaction.close() and another 21% in 
> org.apache.cayenne.conn.DriverDataSource.getConnection(). Only 2% are 
> spent in SelectAction.performAction().
> So it appears that it opens and closes a new connection for every single 
> select query. I must be doing something wrong here! Where can I tell it 
> to re-use connections? Or make one big transaction as it is read-only 
> anyway? Any other hints? I hope I can reduce the processing time to 4% 
> of what it is now...
> Thanks,
> Wernke
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