Il 11/2/2011 1:43 PM, Patrick van Kleef ha scritto: > Hi Roberto, > >> try several times this simple query on http://lod.openlinksw.com/sparql >> (default dataset name: http://dbpedia.org): >> ############# >> SELECT COUNT(DISTINCT ?movie) WHERE { >> ?movie a dbpedia-owl:Film. >> ?movie rdfs:label ?label. >> FILTER ( lang(?label) = "en" ) >> } >> ############# >> You will get each time a different number. :-) >> Now, if you try the same query on http://dbpedia.org/sparql, you wil get >> the "correct" number (at least it does not change!): 60222 >> >> If you remove the filter condition, you will get the same result. > > Did you notice that on http://lod.openlinksw.com/sparql page, the > field Execution Timeout is set to 15000 ? >
Great! Thank you very much Patrick! I was sure that someone from OpenLink Software would have answered to me. :-) Just to take advantage of you, is there a way to setting this parameter for similar queries programmatically, e.g., via Java code? At the moment with Java I use Jena and the sparqlService: ####################### Query query = QueryFactory.create("SELECT ..."); QueryExecution qexec = QueryExecutionFactory.sparqlService("http://lod.openlinksw.com/sparql", query, "http://dbpedia.org"); try { ResultSet results = qexec.execSelect(); while (results.hasNext()) { ... } } finally { qexec.close(); } ####################### > This enables the ANYTIME[1] query option in Virtuoso, which ensures > that Virtuoso will return with whatever records it has found in 15000 > msec, or about 15 seconds of processing time. Depending on other > queries running, this amount will be different between successive runs > explaining the difference you are seeing. > > If you retry your query, but set the field to 0 or empty, then you get > similar behaviour to http://dbpedia.org/sparql and will return 60022. > > Note that on both machines there are (different) maximum timeouts set, > to make sure everyone gets an even share of the resources available on > these services. > > See also: > [1] http://docs.openlinksw.com/virtuoso/anytimequeries.html > > Patrick > --- > OpenLink Software -- roberto mirizzi http://sisinflab.poliba.it/mirizzi ------------------------------------------------------------------------------ RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 _______________________________________________ Dbpedia-discussion mailing list Dbpedia-discussion@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dbpedia-discussion