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From Andrus Adamchik <>
Subject Re: Relationships across databases
Date Mon, 25 Jun 2007 08:34:48 GMT
I think the limitation has been mostly explained by others in this  
thread. So let me try to summarize:

        [works] Saving of related objects.
        [works] Resolving a relationship.
[doesn't work] Doing a query on relationship source qualified on some  
criteria applied to the target objects.


On Jun 21, 2007, at 12:07 AM, Øyvind Harboe wrote:
> In the link below it says that relationships does not work across
> databases "as it will require Cayenne to do in memory cartesian
> product processing".
> What does this qualifier mean? Does it mean that it is possible to
> enable this, but it would take a lot of memory? That this feature was
> considered, but rejected as it would have not worked in all cases?
> For the cases that we need this, there is no problem for Cayenne to
> have both tables completely in memory (always < 1000 records) so I'm
> not concerned about CPU processing power or memory consumption.
> Has any work been done on supporting this?
> We've got a real database (Derby) that has relationships to other
> existing datbases(MS Access/FoxPro databases). We can't move the
> existing databases into Derby due to bug-by-bug compatibility
> problems.
> -- 
> Øyvind Harboe
> - eCos ARM & FPGA  developer kit

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