[Boost-users] Persistent graphs with boost::graph

Hello boost-users, is anybody aware of a library for building persistent graphs (graphs that allow access to a certain number of previous versions of the graph) on top of boost::graph? I don't really need access to versions after every modification, but rather I consider a new version as obtained by a set of modifications that are committed as a vlock, database style. I'm interested in large graphs, so memory sharing across versions is critical. Changes between versions are minimal (few nodes/edges in graphs with O(1M) nodes each with very few edges) Thanks, Maurizio