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From "Jack Klebanoff (JIRA)" <derby-...@db.apache.org>
Subject [jira] Closed: (DERBY-106) HashJoinStrategy leads to java.lang.OutOfMemoryError
Date Tue, 22 Mar 2005 21:59:21 GMT
     [ http://issues.apache.org/jira/browse/DERBY-106?page=history ]
Jack Klebanoff closed DERBY-106:

     Resolution: Fixed
    Fix Version:

Subversion revision 157861

> HashJoinStrategy leads to java.lang.OutOfMemoryError
> ----------------------------------------------------
>          Key: DERBY-106
>          URL: http://issues.apache.org/jira/browse/DERBY-106
>      Project: Derby
>         Type: Bug
>     Reporter: Gerald Khin
>      Fix For:

> My application is running out of memory: I encounterd a java.lang.OutOfMemoryError. I
used -Xmx256M. Unfortunatley, I cannot spend an arbitrary amount of JVM memory. 
> Then, I commented out the line in class OptimizerFactoryImpl which was adding the HashJoinStrategy
to the set of Join strategies:
> 		if (joinStrategySet == null)
> 		{
> //			JoinStrategy[] jss = new JoinStrategy[2];
> 			JoinStrategy[] jss = new JoinStrategy[1];
> 			jss[0] = new NestedLoopJoinStrategy();
> //			jss[1] = new HashJoinStrategy();
> 			joinStrategySet = jss;
> 		}
> And with these changes the OutOfMemoryError has gone away! And it works even with -Xmx128M!!!
> So I guess that there is a major memory issue with this HashJoin strategy implementation.
> If it turns out to be too complicated to make the memory consumption more predicatble
or even bounded to some configurable limit, then I need at least as a workaround a way to
turn off the HashJoin strategy completely: I did it by patching and building my own derby.jar,
but if there would be an official solution with some kind of switch like a system property,
it would be great!

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