Hi,
We use Firebird and at the moment for number of reasons are on the dialect 1 so we are in this situation. We have had to modify the persistence layer and therefore maintain our own build of JBPM different from the standard one. Also we have to maintain the DB schema ourselves and do not let the JBPM touch the schema as any attempt to do that fails. This works fine for us.
As a side note: Microsoft in its WF (Workflow Foundation) solves this issue with callbacks. When it’s time to dehydrate/rehydrate the workflow you receive a callback and it is completely up to you how you persist/load the data. Perhaps, this is the only thing I really love in MS WF.
Thanks,
Vladimir