ここでは、「Example5.java: JOIN_METHODを使用するSPARQL問合せ」と同じSPARQL問合せに、PLAN設定(PLAN=encoded_plan)などの機能を追加した例を示します。この問合せの問合せパターンに関連付けられた実行プランを指定できます。問合せのヒントの詳細は、「問合せのヒント」を参照してください。
import com.hp.hpl.jena.query.*; import org.openjena.riot.Lang; import com.hp.hpl.jena.sparql.core.DatasetImpl; import java.net.URLEncoder; import oracle.rdf.kv.client.jena.*; public class Example5g { public static void main(String[] args) throws Exception { String szStoreName = args[0]; String szHostName = args[1]; String szHostPort = args[2]; // Create connection OracleNoSqlConnection conn = OracleNoSqlConnection.createInstance(szStoreName, szHostName, szHostPort); // Create datasetgraph OracleGraphNoSql graph = new OracleGraphNoSql(conn); DatasetGraphNoSql datasetGraph = DatasetGraphNoSql.createFrom(graph); // Close graph, as it is no longer needed graph.close(); // Clear dataset datasetGraph.clearRepository(); // Load data from file into the dataset DatasetGraphNoSql.load("example.nt", Lang.NQUADS, conn, "http://example.com"); Dataset ds = DatasetImpl.wrap(datasetGraph); String plan = URLEncoder.encode("((qp2 qp3 NLJ) qp1 NLJ)", "UTF-8"); String queryString = " PREFIX ORACLE_SEM_HT_NS: " + " <http://oracle.com/semtech#plan=" + plan + ">" + " PREFIX foaf: <http://xmlns.com/foaf/0.1/>" + " SELECT ?name1 ?name2 " + " WHERE { " + " graph <http://example.org/alice/foaf.rdf> { " + " ?person1 foaf:knows ?person2 . " + " ?person1 foaf:name ?name1 . " + " ?person2 foaf:name ?name2 . " + " } } "; System.out.println("Execute query " + queryString); Query query = QueryFactory.create(queryString); QueryExecution qexec = QueryExecutionFactory.create(query, ds); try { ResultSet results = qexec.execSelect(); ResultSetFormatter.out(System.out, results, query); } finally { qexec.close(); } ds.close(); conn.dispose(); } }
この例をコンパイルして実行するコマンドと、想定されるJavaコマンドの出力は次のとおりです。
javac -classpath ./:./jena-core-2.7.4.jar:./jena-arq-2.9.4.jar: \ ./sdordfnosqlclient.jar:./kvclient.jar:./xercesImpl-2.10.0.jar: \ ./slf4j-api-1.6.4.jar:./slf4j-log4j12-1.6.4.jar:./log4j/1.2.16.jar: \ ./jena-iri-0.9.4.jar:./xml-apis-1.4.01.jar Example5g.java javac -classpath ./:./jena-core-2.7.4.jar:./jena-arq-2.9.4.jar: \ ./sdordfnosqlclient.jar:./kvclient.jar:./xercesImpl-2.10.0.jar: \ ./slf4j-api-1.6.4.jar:./slf4j-log4j12-1.6.4.jar:./log4j/1.2.16.jar: \ ./jena-iri-0.9.4.jar:./xml-apis-1.4.01.jar Example5g <store_name> \ <host_name> <host_port> ------------------- | name1 | name2 | =================== | "Alice" | "Bob" | -------------------