Re: Many-To-Many Relationship across DB with different users
Re: Many-To-Many Relationship across DB with different users
- Subject: Re: Many-To-Many Relationship across DB with different users
- From: David Avendasora <email@hidden>
- Date: Wed, 14 Mar 2012 13:08:42 +0800
On Mar 13, 2012, at 8:13 AM, Chuck Hill wrote:
> It looks like the problem is the join table. Where does that sit? I suspect that Propogate Primary Key is not going to work across databases. You might have to manage that manually.
>
> Chuck
Is this where I put my rant about the evils of join tables with compound PKs? Because it sure seems like it…
Seriously though, Troy, I think this is a situation where you might be better off making the join table between Student and Teacher an actual Entity with a simple PK and separate FKs for Student and Teacher and get rid of propagate primary key. You can still flatten relationships for reading values, but EOF won't automatically create the record in the join table, but how hard is that to do anyway?
Also, be careful with Oracle and cross-schema joins. There can be huge performance differences depending on how the database is configured, especially if the schemas are on different physical/virtual servers.
If you can't make the actual modeled relationship work, you can always approximate it by writing cover methods that do the same work that the normal getters and setters would, but do it with fetches instead. Modeling it is certainly the easiest way to go, but in the situation of cross-schema/cross-database stuff, you are walking in a mine field.
Dave
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