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Let's take for example a created Linked Data View from relational data in Virtuoso . The RDF output therefor should have two graphs which reside in a quad storage named for ex.:

http://example.com/rdfv_demo/quad_storage/default

Also the RDF is accessible over the SPARQL endpoint with the following query:

define input:storage <http://example.com/rdfv_demo/quad_storage/default>
SELECT *
WHERE
  {
    ?s ?p ?o
  }

Now one could ask is there a way to define internally (once) that the quad storage should be included in queries to the SPARQL endpoint? So that the user does not have to define the input:storage explicitly in each query, like this:

http://example.com/sparql?query=select * where { ?s ?p ?o }&default-graph-uri=NULL&named-graph-uri=NULL

All metadata about all RDF storages are kept in "system" graph <http://www.openlinksw.com/schemas/virtrdf#> ( namespace prefix virtrdf: ). Subjects of type virtrdf:QuadStorage are RDF storages. There are three of them by default:

SQL> SPARQL SELECT * FROM virtrdf: WHERE { ?s a virtrdf:QuadStorage };
s
VARCHAR
_______________________________________________________________________________

http://www.openlinksw.com/schemas/virtrdf#DefaultQuadStorage
http://www.openlinksw.com/schemas/virtrdf#DefaultServiceStorage
http://www.openlinksw.com/schemas/virtrdf#SyncToQuads

3 Rows. -- 3 msec.

There are two ways of using the Linked Data View from above in SPARQL endpoint without define input:storage :