We have objects spanning over several databases, I can't seem to find documentation on how to setup more than one connection and map objects to these alternate connections.

Not sure if I'm understanding your question fully, but if you are talking about an object that persists data across two separate databases, this is a Hibernate 3 feature and I doubt it has been implented in NHibernate.

-devon

Each SessionFactory can only handle one database. You can create several SessionFactories though (one for each DB), but there will be no relationship between them.

Regards,
Lars Arne Brekken

Seems like a stupid question, but how do I build diffrent session factories with hibernate.cfg.xml or web.config ?

Depends on how you get your Configuration instance. For ex you could have some function that opens the session - and you need a session per database. So you call your function with some parameter that would make difference:

seesion1 = OpenSession("Path1")
session2 = OpenSession("Path2")


Then in the OpenSession function you feed this path to NHibernate.Cfg.Configuration:

NHibernate.Cfg.Configuration.Configure("Path to file")

Something like this...

I have an app using NHibernate calling multiple databases on the same MSSQL server. I set up all my mapping files where the table names are denoted as databaseA..table1, databaseB..table5, etc.. Then my single session factory treats all the databases as a single database.

Does this allow you to have relationships between tables across those databases?

You sure can, as long as you fully qualify each table in the mapping file (ie. Northwind.dbo.Products).

This also works if you are using databases from two different SQL Servers, as long as you create a linked-server connection between the two (through enterprise manager). But then you need to qualify the table names with the server name as well (ie. MySQLServer2.Northwind.dbo.Products).

I've used this to string together several different databases on different servers. It may not be the most performant method, but it is the most structured. Make sure you configure DTC on each server correctly.

Thanks tylord!

This should get me around one issue I was having with nhibernate and understanding how I can link multiple databases together.

I was previously creating views in one database that showed tables from another database but I seriously did not like the though of doing this, especially when it came to running updates.