Hello Jena community, I'm looking for a possibility to SPARQL two different TDB backed datasets within one query. The background is that I have a few TDB stores (say A and B) and one special TDB store S containing a few triples that I want to "share" with the other stores. For instance I want to do something like this:SELECT ?o WHERE { GRAPH <S> { ?s ?p ?o. } GRAPH <A> { ?s1 ?p1 ?o.} } In addition, S needs to be writeable and the changes need to be promptly visible for other queries. Even if I change A to B in the above example. I know about named graphs but unfortunately they are no option in our scenario. Could I do it by using assemblers? Or is there any other possibility? We use the current versions of Jena/ARQ/TDB in pure Java.
You can create a single dataset with graphs from different storages, the your queries will look exactly as in your example.
This can be done in an assembler or in code. Example: http://jena.apache.org/documentation/tdb/assembler.html#mixed-datasets Andy
