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 ? 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 ------------------------------------------------------------------------------ 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
