Re: [Wikidata] Linked Data Fragments endpoint returns IllegalStateException

Hello!

This looks like a bug, but we'll need more time to investigate and get to the bottom of this. I've created https://phabricator.wikimedia.org/T2704 to track the issue. There isn't that many people around during this end of year, so this will probably have to wait for January.

Thanks for your patience!

Guillaume

On Thu, Dec 17, 2020 at 4:06 PM Maciej Gawinecki mgawinecki@gmail.com wrote:

Hi,

I am trying to get alternative names of given names in WikiData with the following simple query:

PREFIX ps: <http://www.wikidata.org/prop/direct/>
PREFIX wd: <http://www.wikidata.org/entity/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
CONSTRUCT {?s rdfs:label ?o}
WHERE { ?s ps:P31 wd:Q202444. ?s rdfs:label ?o}
LIMIT 1000

Initially, the query was much more complex, but I was getting time-outs on the public WikiData SPARQL endpoint. I decided to use Linked Data Fragments to offload some filtering from the server to the client.

comunica-sparql "https://query.wikidata.org/bigdata/ldf" -f query >

given_names.n3

(where "query" is a file with the SPARQL query shown above). Unfortunately, the client tries to get output from the 3rd page, I am getting the following error:

Could not retrieve

https://query.wikidata.org/bigdata/ldf?subject=http%3A%2F%2Fwww.wikidata.org... (500: unknown error)

Following the link in fact returns HTTP 500 error with

Error details
java.lang.IllegalStateException

The link points to the 3rd page. It works if you try to go the second page: https://query.wikidata.org/bigdata/ldf?subject=http%3A%2F%2Fwww.wikidata.org...

Is this a bug or a limitation of a service?

With kind regards, Maciej Gawinecki _______________________________________________ Wikidata mailing list Wikidata@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikidata