Hi, I am currently performing some data analysis on our local DBpedia dataset running on a Virtuoso 6 server. For that I need to execute a large amount of SPARQL DESCRIBE queries against the local Virtuoso SPARQL endpoint - in a single run approx. 400.000 queries. I know that this will take some time, but that's not the problem if the execution time for a single query remains constant.
The problem I am experiencing right now is that with an increasing number of DESCRIBE queries executed against a single SPARQL endpoint, the response time for a single DESCRIBE queries goes up almost linear. The first hundred queries take a few ms, the queries > 3000 take a few hundred ms in our local environment. I have tested this also against the public DBpedia endpoint and noticed a similar behavior. I've attached a code snippet that illustrates the problem. Can anybody
SPARQLDescribePerformance.java
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tell me if the problem is on the client or the server side? Maybe I have missed sth... Are there any db-parameters to increase the performance of DESCRIBE queries? Thx, Bernhard ______________________________________________________ Research Group Multimedia Information Systems Department of Distributed and Multimedia Systems Faculty of Computer Science University of Vienna Postal Address: Liebiggasse 4/3-4, 1010 Vienna, Austria Phone: +43 1 42 77 39635 Fax: +43 1 4277 39649 E-Mail: [email protected] WWW: http://www.cs.univie.ac.at/bernhard.haslhofer
