AGSparqlPlanner.java
package com.franz.agbase.examples;
import com.franz.agbase.*;
public class AGSparqlPlanner {
/**
* Demonstrates how to set the query planner 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 fresh triple-store for this example.
AllegroGraph ts = ags.renew("sparqlplanner", AGPaths.TRIPLE_STORES);
// Load the Kennedy data set
AGLoadNtriples.loadNTriplesWithTiming(ts, AGPaths.dataSources("kennedy.ntriples"));
// Index the store
AGIndexAllTriples.indexAllTriplesWithTiming(ts);
// This query is written declaratively with no consideration for efficiency.
String query =
"PREFIX ex: <http://example.org/kennedy/> " +
"PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> " +
"SELECT ?father ?mother ?child ?univ " +
"WHERE {" +
"?father rdf:type ex:person . " +
"?mother rdf:type ex:person . " +
"?mother ex:spouse ?father . " +
"?child rdf:type ex:person . " +
"?father ex:has-child ?child . " +
"?mother ex:has-child ?child . " +
"?father ex:alma-mater ?univ . " +
"?child ex:alma-mater ?univ . " +
"}";
// Query the store using the (default) Variable Coverage planner; this
// planner will do some reordering of the query's graph patterns in an
// effort to provide results efficiently.
SPARQLQuery sq = new SPARQLQuery();
sq.setTripleStore(ts);
sq.setQuery(query);
sq.setPlanner(SPARQLQuery.PLANNER.COVERAGE);
AGSparqlSelect.doSparqlSelect(sq);
// Query the store using the Identity planner; this planner will not do
// reordering of the query's graph patterns (it might take a little longer
// because the graph patterns aren't ordered favorably). The Identity
// planner is useful for applications that want the specified ordering
// respected. See also AGLubm50Sparql.java for examples that use the
// Identity planner.
sq.setPlanner(SPARQLQuery.PLANNER.IDENTITY);
AGSparqlSelect.doSparqlSelect(sq);
// Close the triple store and disconnect from the server.
ts.closeTripleStore();
ags.disable();
}
}
| Copyright © 2023 Franz Inc., All Rights Reserved | Privacy Statement | 
|
|
|
|
|
|