Clojurians Log v2

Fantastic, thank you for the thorough explanation. I need to dive into all of this more 😄

I don't know all the specifics, but see https://en.wikipedia.org/wiki/Named_graph

While it’s certainly possible to implement SPARQL without multiple graph support, this would be a subset of the spec.

SPARQL defines a "default graph". This actually has 2 meanings, though I doubt many people would agree to that (argh!)

Anyway, when you're querying with SPARQL, each part of your query will be getting data from the "default graph", unless you explicitly state otherwise.

The "default graph" is defined in your query as either: • a system default • the union of all the graphs that you've listed as FROM clauses

So, if you don't say anything, your get the system default. But if you say: FROM medical:snomed then your query will default to using medical:snomed. If you say:

FROM medical:snomed
FROM medical:icd10

But then you can ALSO add in "named graphs"

If you've named a graph, then you can select from it explicitly:

SELECT ?name ?generalName
FROM medical:snomed
FROM NAMED medical:icd10
{ GRAPH medical:icd10 { ?disease skos:notation "C43.9" ;
                                 rdfs:label ?name }
  ?snomedDisease rdfs:name ?name ;
                 rdfs:subClassOf ?parent .
  ?parent rdfs:label ?generalName }

The examples here are contrived, but they show a common approach: different datasets in different graphs. You can then select from each dataset as appropriate. This is particularly important for datasets that share some entities, but have different descriptions for them (such as different rdfs:label values)

I do this sort of thing all the time using Stardog, GraphDB, or Jena. I would like to do it with Asami