Hi!

Le mer. 14 août 2019 à 01:10, Kingsley Idehen <kidehen@openlinksw.com> a écrit :

We have loaded Wikidata into a Virtuoso instance accessible via SPARQL [1]. One benefit is helping to understand Wikidata using our Faceted Browsing Interface for Entity Relationship Types [2][3].

That's great news, thanks!

Hi Jérémie,

You are welcome!  See responses below.

Feedback always welcome too :)

So, I've eagerly tried a very simple SPARQL query with a huge result
set, the complete version of which¹ I've known for several years to
timeout in both the official Blazegraph instance and a personal
Blazegraph instance with supposedly all time limits removed:

  PREFIX wd: <http://www.wikidata.org/entity/>
  PREFIX wdt: <http://www.wikidata.org/prop/direct/>

  SELECT ?person WHERE {
    ?person wdt:P31 wd:Q5
  }

… and while the Virtuoso instance manages to answer pretty quickly, it
seems that it's cutting the result set at 100k triples. Is it the
expected behavior? 

Yes.

If so, I suggest you show that in the UI because
apart from the improbable round number of triples, it's not obvious
that the result set is incomplete (in this case, the LDF endpoint
tells us that there should be around 5,4M triples²).

Thanks again!

¹ ie. using the wikibase:label service
² https://query.wikidata.org/bigdata/ldf?subject=&predicate=wdt%3AP31&object=wd%3AQ5

If you open up your browser's inspector you will see:

cache-control: max-age=3600
content-encoding: gzip
content-type: text/html; charset=UTF-8
date: Wed, 14 Aug 2019 16:47:47 GMT
expires: Wed, 14 Aug 2019 17:47:47 GMT
server: Virtuoso/08.03.3315 (Linux) x86_64-generic-linux-glibc25  VDB
status: 200
strict-transport-security: max-age=15768000
vary: Accept-Encoding
x-sparql-default-graph: http://www.wikidata.org/
x-sparql-maxrows: 100000

In addition, note that Virtuoso has an "Anytime Query" feature [1][2] that it uses to drive a "Fair Use" policy that ensures an endpoint is able to handle a cocktail of query types from users and bots. This is also how we handle DBpedia and DBpedia-Live instances [3]. Naturally, HTTP response metadata will also inform you when this kicks in.

[1] http://docs.openlinksw.com/virtuoso/anytimequeries/

[2] http://vos.openlinksw.com/owiki/wiki/VOS/VirtTipsAndTricksAnytimeSPARQLQuery

[3] https://wiki.dbpedia.org/public-sparql-endpoint

-- 
Regards,

Kingsley Idehen	      
Founder & CEO 
OpenLink Software   
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