Question about doing RDF analysis in Ruby

Hello,

We are using RDF.rb now for persisting RDF data into our CouchDB
RDF::Repository.  We believe that we will be splitting the data into
different repositories in order to shard and distribute the data between
different locations, but we are definitely interested in doing analysis and
inferences on the data spanning multiple repositories.  What is the general
approach for doing this kind of thing with RDF.rb?  Is there a SPARQL
implementation for RDF.rb that would help with this?  Or would we have to
write ruby code to walk the repos and do the queries programatically?

Thanks!

Greg