How to avoid timeout, i.e., do time-unlimited query, on Virtuoso SPARQL endpoint?

Question

Every time I do a query in http://dbpedia.org/sparql endpoint or my local Virtuoso store, I get a time out error after some considerably large time (like 30 mins through my own experience) .

For querying DBpedia's online SPARQL endpoint, I use the following statements:

Query query = QueryFactory.create(q); //q - query string
QueryExecution qexec = QueryExecutionFactory.sparqlService("http://dbpedia.org/sparql/", query);
qexec.setTimeout(-100);

I read that Timeout value less than zero (i.e., negative) will never allow a timeout to happen, so I have set qexec.setTimeout(-100) value. But still I get a timeout.

How to solve this problem? Is it also true that http://dbpedia.org/sparql blocks your IP address after certain amount of large queries? Can I not run continuous unlimited (i.e., very large, 10^6) queries? Thanks.

Answer 1

Questions specifically regarding Virtuoso are generally best raised on the public OpenLink Discussion Forums, the Virtuoso Users mailing list, or through a confidential Support Case.

That said, regarding your specific questions -- the server-side timeout setting trumps that requested by any query -- i.e., the query setting only has effect when it's shorter than that set on the server. You can adjust the server-side setting (MaxQueryExecutionTime), among many other things, on your own instance.

DBpedia-specific questions, discussion, submissions, etc., are usually best directed to the DBpedia discussion list. The public DBpedia endpoint does indeed have various usage limitations, which are part of what make it viable as a generously provided public service.