I have a general question about the best approach for copying data between two databases managed by Hibernate. I have as of yet have not found a set of best practices for his.

We are using:
* Eclipse RCP 3.3
* Java 1.5
* Hibernate 3
* HSQL 1.8

Basically, we are deploying a desktop application to our customers. We have a need to be able to import from one application's database (A) to the user's application database (B).

The issues I have:
1. Configure HSQL to support two databases (outside of scope on this forum)
2. Configure Hibernate to talk to both databases simultaneously
3. Copy an object from database A to database B

As for issue 2, I believe it is a simple matter of multiple session factories, one for each database. I then have DAOs use the correction session factory.

As for issue 3, do I need to do a deep copy? Or there other means of taking an object from DB A, sanitizing it and then creating a new instances in DB B?[/list]

Yes, this is indeed correct. Just create multiple session factories with individualized hibernate_dbx.cfg.xml files, and make sure the DAOs are associated with the appropriate session factory. A bit of work, but not too much.



Indeed, a deep copy will be needed to ensure you don't lose any data.

You can always entertain Hibernate Shards as well.

Good luck!

Thanks. It is good to know we are headed in the right direction.



I am curious. Is it possible to re-use objects by resetting the object id to null and handing to a different session factory session? I hope yes; however, given that we have proxy objects associated with another session factory session that doing so may cause hiccups. Thoughts? Experiences?

I believe you can use this:

http://docs.jboss.org/hibernate/core/3.6/reference/en-US/html_single/#objectstate-replicating