ISSUE-26: Producing triples in named graphs and the default graph

Named graphs and default graph

Producing triples in named graphs and the default graph

State:

CLOSED

Product:

R2RML

Raised by:

David McNeil

Opened on:

2011-03-02

Description:

From the editor's draft of the R2RML spec (http://www.w3.org/2001/sw/rdb2rdf/r2rml/):

Section 1.4

"By default, all RDF triples are in the unnamed default graph of the RDF dataset. A TriplesMap can contain optional rules that place some or all of the triples into named graphs instead."

Section 3.3.1

"This optional property [, rr:graph, ] specifies a graph IRI. All the RDF triples generated from a logical table row will be stored in the specified named graph. In the following example, all the RDF triples generated from a logical table row will be in the named graph exa:DeptGraph."

The rr:graph property has a cardinality of "min=0, max=unlimited"

This seems to allow triples to be produced either in the default graph or a set of named graphs, but not in the default graph _and_ a set of named graphs. I think we need to clarify the wording to indicate which of these is intended:

1) Allow a TriplesMap to produce the triple for a logical row in the default graph and a set of named graphs. One way to achieve this would be to define a value for the rr:graph property that means "default graph". Alternatively the user would need to define another TriplesMap to produce the same triples in the default graph and named graphs.

2) Require that all of the triples are always produced in the default graph.

3) Only allow triples to be produced in either the default graph or a set of named graphs. This strikes me as an odd restriction.

An underlying issue to come to terms with is how the R2RML spec relates to the freedom the SPARQL spec (http://www.w3.org/TR/2008/REC-rdf-sparql-query-20080115/#exampleDatasets) allows for defining the relationship between the default graph and named graphs. Specifically it seems that the R2RML mapping is trumping the SPARQL implementation's ability to define the relationship between the default graph and named graphs.

Related Actions Items:

• ACTION-111 on Souripriya Das to clarify that with use of (newly introduced) rr:defaultGraph value for rr:graph property of a PredicateObjectMap, we now allow triples to be produced either in the default graph, or a set of named graphs, or the default graph as well as a set of named graphs - due 2011-03-26, closed

Related emails:

1. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from privera.salas@gmail.com on 2011-03-22)
2. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from souripriya.das@oracle.com on 2011-03-22)
3. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from ivan@w3.org on 2011-03-22)
4. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from souripriya.das@oracle.com on 2011-03-22)
5. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from juanfederico@gmail.com on 2011-03-22)
6. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from michael.hausenblas@deri.org on 2011-03-22)
7. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from ashok.malhotra@oracle.com on 2011-03-22)
8. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from marcelo.arenas1@gmail.com on 2011-03-22)
9. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from michael.hausenblas@deri.org on 2011-03-22)
10. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from bvillazon@fi.upm.es on 2011-03-22)
11. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from michael.hausenblas@deri.org on 2011-03-21)
12. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from souripriya.das@oracle.com on 2011-03-21)
13. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from michael.hausenblas@deri.org on 2011-03-21)
14. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from michael.hausenblas@deri.org on 2011-03-21)
15. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from richard@cyganiak.de on 2011-03-21)
16. Re: RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from souripriya.das@oracle.com on 2011-03-19)
17. RDB2RDF WG agenda for 2011-03-22 meeting 1600 UTC (from michael.hausenblas@deri.org on 2011-03-19)
18. Re: Minutes of 2011-03-15 telecon (from eric@w3.org on 2011-03-17)
19. Re: R2RML: publishing the second draft (from bvillazon@fi.upm.es on 2011-03-17)
20. Re: R2RML: publishing the second draft (from me@alexdeleon.name on 2011-03-16)
21. Re: R2RML: publishing the second draft (from rscanlon@revelytix.com on 2011-03-15)
22. Re: R2RML: publishing the second draft (from bvillazon@fi.upm.es on 2011-03-15)
23. Minutes of 2011-03-15 telecon (from michael.hausenblas@deri.org on 2011-03-15)
24. Re: R2RML: publishing the second draft (from rscanlon@revelytix.com on 2011-03-15)
25. Re: R2RML: publishing the second draft (from me@alexdeleon.name on 2011-03-15)
26. Re: R2RML: publishing the second draft (from bvillazon@fi.upm.es on 2011-03-15)
27. R2RML: publishing the second draft (from souripriya.das@oracle.com on 2011-03-14)
28. Re: RDB2RDF WG agenda for 2011-03-08 meeting 1700 UTC (from michael.hausenblas@deri.org on 2011-03-08)
29. Re: RDB2RDF WG agenda for 2011-03-08 meeting 1700 UTC (from bertails@w3.org on 2011-03-07)
30. RDB2RDF WG agenda for 2011-03-08 meeting 1700 UTC (from michael.hausenblas@deri.org on 2011-03-06)
31. ISSUE-26 (Named graphs and default graph): Producing triples in named graphs and the default graph [R2RML] (from sysbot+tracker@w3.org on 2011-03-02)

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