Thanks for the link. Dug around a bit and from what I can tell they are pretty similar. Object databases have been referred to as hierarchical databases (I.e. X

Thanks for the link. Dug around a bit and from what I can tell they are pretty similar. Object databases have been referred to as hierarchical databases (I.e. XML data), many of the key-value databases being touted in the past couple of years seem hierarchical to me, only with some additional indexing and query language packaged on top (which you could add yourself with Lucene or Sphinx I would assume). I must be missing something, but I'll keep digging.