virtuoso | 易学教程

I am trying to get list of all the authors who have had more than 3 piece of work - DBpedia Sparql

阅读更多关于 I am trying to get list of all the authors who have had more than 3 piece of work - DBpedia Sparql

问题 I am trying to get list of all the authors who have had 3 or more piece of work done (in DBpedia). my example can be run on : http://dbpedia.org/sparql base code select (count(?work) as ?totalWork), ?author Where { ?work dbo:author ?author. } GROUP BY ?author I get each authors total amount of piece of work done. But when I try to filter to show only list of author that have more than 3 piece of work. I get error: I tried HAVING keyword or using FILTER keyword. Using Filter select (count(

How to check prefix of variables in SPARQL?

阅读更多关于 How to check prefix of variables in SPARQL?

I want to find how many resource is there in an RDF but I can't find any tutorial to explain how can I check the prefix of variables in my SPARQL. I have tried this: select count(?x) where { res:?x ?p ?v } but it has syntax error. I am using virtuoso for DBPedia You can use strstarts(string,prefix) to check whether string begins with prefix . You can use the str function to get the string representation of a IRI, including IRIs generated from prefixes. E.g., if you have prefix ex: <http://example.org/> , then ex: by itself is a legal IRI, and str(ex:) produces "http://example.org/" . That

SPARQL: Delete instance and all of its properties with linked subproperties

阅读更多关于 SPARQL: Delete instance and all of its properties with linked subproperties

I have a question about the deletion of elements from a triplestore (in my case a Virtuoso) using SPARQL. I have stored the following elements in a graph: @prefix xy: <http://purl.oclc.org/xy/xy#> . @prefix ssn: <http://purl.oclc.org/NET/ssnx/ssn#> . <point> a xy:Point ; xy:value "10" ; ssn:observationResultTime <Rs_b8d4ae44-6083-4140-b4e3-11fcf38a53c8> ; ssn:observationSamplingTime <St_b8d4ae44-6083-4140-b4e3-11fcf38a53c8> ; ssn:observedBy <SensorID-b8d4ae44-6083-4140-b4e3-11fcf38a53c8> . As you can see I have one xy:Point, which has some properties. In my database I have stored dozens of

Complex SPARQL query - Virtuoso performance hints?

阅读更多关于 Complex SPARQL query - Virtuoso performance hints?

问题 I have a rather complex SPARQL query, which is executed thousands of times in parallel threads (400 threads). The query is here somewhat simplified (namespaces, properties, and variables have been reduced) for readability, but the complexity is left untouched (unions, number of graphs, etc.). The query is run against 4 graphs, the biggest of which contains 5,561,181 triples. PREFIX graphA: <GraphABaseURI:> ASK FROM NAMED <GraphBURI> FROM NAMED <GraphCURI> FROM NAMED <GraphABaseURI> FROM NAMED

Complex SPARQL query - Virtuoso performance hints?

阅读更多关于 Complex SPARQL query - Virtuoso performance hints?

I have a rather complex SPARQL query, which is executed thousands of times in parallel threads (400 threads). The query is here somewhat simplified (namespaces, properties, and variables have been reduced) for readability, but the complexity is left untouched (unions, number of graphs, etc.). The query is run against 4 graphs, the biggest of which contains 5,561,181 triples. PREFIX graphA: <GraphABaseURI:> ASK FROM NAMED <GraphBURI> FROM NAMED <GraphCURI> FROM NAMED <GraphABaseURI> FROM NAMED <GraphDBaseURI> WHERE{ { GRAPH <GraphABaseURI>{ ?variableA a graphA:ClassA . ?variableA graphA