Hi,

I posted a question on Friday regarding data migration and have since found a similar unanswered post from the beginning of September.

I've got fairly close to a solution but it's pretty hairy and if there's a better way to achieve what I'm trying to do, I'd love to hear some suggestions.

Basically all that I want to do is migrate data from one database to another. During testing, I have test DB but, all going well, I'd like to migrate the data generated during testing across to another DB where it will be stored more permanently. Same DB provider and same schema.

I guess what I need to do is load all persistent objects in using Session Factory A (configured to use the test DB) then convince hibernate that it's never seen the objects before and save them using Session Factory B (configured to use the release DB).

It's the "convince hibernate that it's never seen the objects before" bit I'm struggling with.

I'm currently using reflection to introspect all of the objects and set 'id' fields to null. Just about working but a few complications with array attributes and various other nasties.

This does however seem very similar to what hibernate does when initially determining whether a saveOrUpdate is required and if there's another way to do it, it would be preferable to hand coding.

The same problem would need to be solved when moving from one DB vendor to another so I'm hoping there's a more obvious way to do this that I've not stumbled upon.

Cheers,
Jeremy.

Just some additional information.
The replicate() method is almost what I'm looking for in that it will allow me to save the data if there aren't any conflicting ids.

After a couple of test data->release data migrations I'm going to run into problems when replicating data with the same id.

I think that what I need is a detached -> transient state change.

Any offers?

Okeydoke.

Utilising some very messy introspection I've managed to null out most of the IDs in my classes. Where I've succeeded, I've got the required behaviour.

Unfortunately the plethora of exceptional cases along the lines of:



is proving damaging to my health.

I can't be the only person to have tried to migrate data from one database to another...What's the secret?

I don't know been strugling myself. Setting ids to -1 and another "solution" being having assigned as primary key generator and then using replicate()

I have no idea if this would work, but could you set an interceptor on the second database Session/Configuration to null out any id fields on save? (I qualify this by saying I haven't looked to see whether onSave is called before or after the save vs. update decision has been made).