Hi Alex,

2005/8/16, Alex Boisvert <boisvert@intalio.com>:
Supporting the Collections API is on our TODO list; there are a few
patches floating around that may help you get started.  We'll work on
integrating those to the base distribution shortly.

What hinders the performance of JDBM is the object serialization mechanism of JDBM.  It doesn't optimize an object descriptor catalog so that it increases the amount of data serialized to the disk, and it results degraded performance.  Please take a look at BDB JE object serialization code which performs better, and we could get more than that.

As for JTA support, this is a more complex subject.  JDBM isn't a real
OLTP provider; it doesn't natively support multiple concurrent
transactions.  We do have basic commit/rollback semantics but we don't
have any of the more refined transaction support that you would normally
find in a complex database system such as optimistic/pessimistic
locking, MVCC, etc.

It would be really nice if JDBM can support multiple concurrent transactions.  We're using JDBM as an Apache Directory Server backend storage, but it makes us hard to use it for the situation that requires more isolation level.  Is there any way to achieve the higher isolation level in JDBM?

what we call human nature is actually human habit