[Jdbm-general] Sharing objects

[Brian O'N. <Bri...@di...>]

I think JDBM is a great little persistence engine with tons of potential.
Its nice to see such a project like this being actively developed. I do see
some things that can be improved.

When I save a key or value into a JDBM table, the object is serialized in
its own stream. If this object has a reference to another shared object, the
original object graph is not preserved across hash table entries. The
approach that JDBM uses to serialize also has space overhead from all the
stream headers and class info written to each record.

I like the simple interfaces provided in the HTree and BTree, but since they
do nothing special to preserve object graphs, I think an interface that
operates on byte[] keys and values is more flexible. A simple object
serialization strategy could be placed above this level, or a more
sophisticated persistence model could be developed with less storage
overhead.

Separating the HTree and BTree from the RecordManager is really nice. I
think more levels of layering will make it easier to develop many kinds of
persistence models. Making object persistence available at the RecordManager
level might not be the best place for this, since I consider this to be a
very "high level" function.

I'm going to start mucking with JDBM, to see how feasible it is to have
higher level tree implementations built upon simpler ones. Has there been
any other talk of this, or have there been any such implementations?


___________
Brian S O'Neill