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From "Mike Kienenberger" <>
Subject Re: Relationships across databases
Date Thu, 21 Jun 2007 15:15:27 GMT
I think Juergen might be right in that you can save across databases
without an issue -- it'll only be querying that causes a problem.

However, you might have to force your own database operation sorting
algorithm to be sure everything works.   But this is just speculation
on my part.

However, I disagree with Juergen's comments of "I think this special
problem has to be solved by YOU and not by the cayenne-team" -- it's
probably true in this instance (since there's no built-in support in
Cayenne), but there's no reason that Cayenne could not attempt to
solve it down the road.

The need to work simultaneously with heterogeneous databases is a real
one, and will probably only increase as time passes.   I'm fortunate
in that in my own scenario, all of the databases involved are Oracle
databases on the same server, and Oracle provides a way to link the
databases together transparently at the database level.

On 6/21/07, Juergen Saar <> wrote:
> Don't know if I have the right understanding:
> In cayenne relations pointing to a different database
> as the root-Object work fine. What can't and
> shouldn't work is querying such relations.
> So the default-getter/setter for such relations should
> even work on uncommited changes,
> because for this there is the cayenne ObjectStore
> 2007/6/21, Øyvind Harboe <>:
> >
> > On 6/21/07, Juergen Saar <> wrote:
> >
> > W.r.t. foreign key references, my problem is that I don't know how to
> > implement a get/set relationship methods in the CayenneDataObject
> > subclasses in a way that works for uncommitted changes.
> >
> > --
> > Øyvind Harboe
> > - eCos ARM & FPGA  developer kit
> >

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