AGSparqlLimitOffset.java
package com.franz.agbase.examples;
import com.franz.agbase.*;
public class AGSparqlLimitOffset {
/**
* Demonstrates basics of using LIMIT and OFFSET in SPARQL
*
* @param args unused
* @throws AllegroGraphException
*/
public static void main(String[] args) throws AllegroGraphException {
// Connect to server, which must already be running.
AllegroGraphConnection ags = new AllegroGraphConnection();
try {
ags.enable();
} catch (Exception e) {
throw new AllegroGraphException("Server connection problem", e);
}
// Create a fresh triple store
AllegroGraph ts = ags.renew("sparqllimitoffset", AGPaths.TRIPLE_STORES);
// Load the Kennedy data
AGLoadNtriples.loadNTriplesWithTiming(ts,AGPaths.dataSources("kennedy.ntriples"));
// Index the store for querying, wait until indexing is complete.
ts.indexAllTriples(true);
// Query for the first 20 place names ordered by name
String query =
"PREFIX ex: <http://example.org/kennedy/> " +
"SELECT ?name " +
"WHERE { ?place ex:name ?name } " +
"ORDER BY ?name " +
"LIMIT 20";
// Query the store and show the results
SPARQLQuery sq = new SPARQLQuery();
sq.setTripleStore(ts);
sq.setQuery(query);
AGSparqlSelect.doSparqlSelect(sq);
// Now query using an OFFSET to skip the first 5 places
// and provide the next 10, ordered by name -- check this
// against the above solutions
query =
"PREFIX ex: <http://example.org/kennedy/> " +
"SELECT ?name " +
"WHERE { ?place ex:name ?name } " +
"ORDER BY ?name " +
"OFFSET 5 " +
"LIMIT 10";
// Query the store and show the results
sq.setQuery(query);
AGSparqlSelect.doSparqlSelect(sq);
// Close the triple store and disconnect from the server
ts.closeTripleStore();
ags.disable();
}
}
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