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I wanted to try out some of the examples in this article, but I get very inconsistent results depending on the SPARQL Query Processor I'm using. I have tried out the most basic example:

SELECT DISTINCT ?p
FROM <http://worldcat.org/entity/work/id/67201841>
WHERE
  { ?s ?p ?o.
  }

This works with http://sparql.org/sparql.html, but fails with all the other processors I have tried such as http://sparql-playground.sib.swiss/, https://dbpedia.org/sparql etc. These all produce no result. https://query.wikidata.org/ produces an error Unknown error: NAMED clauses in queries are not supported in triples mode.

Could anyone explain why this query fails?

logi-kal
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user3685604
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    it fails because nobody wants to retrieve data from external sources in that way. It worked some time ago in Jena (which is the backend of sparql.org) but this is not mandatory by SPARQL standard to allow for remote data retrieval. Virtuoso does support something via Sponger modules (check their docs) – UninformedUser Nov 22 '19 at 12:29
  • Is there a way of retrieving remote RDF data through a SPARQL query, besides downloading the data locally or using a SPARQL endpoint? – user3685604 Nov 22 '19 at 12:56
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    I don't think so, but maybe some triple stores do support this. I mean, in the end the data would have to be loaded anyways by the triple store. And even if such a features exists it would be disabled for public SPARQL endpoints to avoid loading (eventually huge) data all the time. As I said, Virtuoso has some Sponger modules, check their docs please. – UninformedUser Nov 23 '19 at 04:25

0 Answers0