Re: Design question: are cross database ManyToMany relationships possible
Re: Design question: are cross database ManyToMany relationships possible
- Subject: Re: Design question: are cross database ManyToMany relationships possible
- From: David Avendasora <email@hidden>
- Date: Mon, 08 Aug 2011 06:18:38 +0800
On Aug 8, 2011, at 5:19 AM, Lars Sonchocky-Helldorf wrote:
> Dear List,
>
>
> I've got a design question: Is it possible to manage cross database ManyToMany relationships with EOF?
I believe that at the point of cross-DB-anything, you are no longer talking about what WO/EOF can do, you are talking about what the database engine itself is capable of.
Can you write a query that joins across two databases in a regular SQL client? In my experience with both Oracle and MSSQL it is possible to have cross-database relationships but you have to setup some things that then have other implications, especially if the DBs are on different physical servers.
The easy answer is to just use cover methods that do the same things as EOF relationships, only using fetch specifications, but then that has implications when it comes to qualifying and sorting.
Dave
>
>
> Googling the topic brought up:
>
> http://lists.apple.com/archives/webobjects-dev/2003/Feb/msg00395.html
>
> which gives me the faint hope that such things are possible. But then again almost all of the other search results gave me the impression that this isn't possible.
>
>
> Hence my question to the pros: Are such constructs possible, if so what do I have to pay attention to (Of course I tried and failed before asking this question ;-))? What are the pitfalls?
>
> If this is not possible I'd like to know what kind of solutions you use in such situations: duplicate tables (which bear the risk of divergence)?
>
>
> thanks & cheers,
>
> Lars _______________________________________________
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