Querying a set of named RDF graphs without naming the graphs

A big step toward using named graphs to track provenance.

I’d like to thank everyone who added comments to my last post, Some questions about RDF named graphs. Lee Feigenbaum wrote an entire blog post addressing the issues I raised, and it looks like his Open Anzo triplestore (which I’ll write up in its own post soon) has some nice support for versioning, access control, and replication.

Just about all the RDF triplestores I’ve been trying were designed from the ground up to store RDF triples. OpenLink Software’s Virtuoso is a database server that can also store (and, as part of its original specialty, serve as an efficient interface to databases of) relational data and XML, so some of my setup and usage steps required learning a few other aspects of it first. For example, the actual loading of RDF is done using Virtuoso’s WebDAV support, so I had to learn a…