I wonder how hard it would be to write an Apache::ZODB module
using
Inline::Python.pm and
ZODB.py ...
Kalvis Apsitis : Specification of an RDF Crawler
"[An RDF Crawler] is a tool which downloads interconnected fragments of RDF from the Internet and builds a knowledge base from this data. At every phase of RDF crawling we maintain a list of URIs to be retrieved as well as URI filtering conditions (e.g. depth, URI syntax), which we observe as we iteratively download resources containing RDF."