AGPrologQueryPlanner.java
package com.franz.agbase.examples;
import com.franz.agbase.*;
public class AGPrologQueryPlanner {
/**
* Demonstrates some basics of using the Prolog query planner.
*
* @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 for this example.
AllegroGraph ts = ags.renew("queryplanner", AGPaths.TRIPLE_STORES);
// Load the Kennedy data
AGLoadNtriples.loadNTriplesWithTiming(ts, AGPaths.dataSources("kennedy.ntriples"));
// Index the store for faster querying
AGIndexAllTriples.indexAllTriplesWithTiming(ts);
// Register any namespaces
ts.registerNamespace("ex", "http://example.org/kennedy/");
// Set up a Prolog query object
PrologSelectQuery q = new PrologSelectQuery();
q.setTripleStore(ts);
// Find parents and children that went to ivy league schools
q.setVariables(new String[]{"x","y"});
String pquery = "(q ?x !ex:alma-mater ?am)" +
"(q ?am !ex:ivy-league !ex:true)" +
"(q ?x !ex:has-child ?y)" +
"(q ?y !ex:alma-mater ?am2)" +
"(q ?am2 !ex:ivy-league !ex:true)";
q.setQuery(pquery);
// Prepare a plan and show it (but don't run it yet)
System.out.println("Prepare a query plan: " + q.preparePlan());
System.out.println(q.showPlan());
// Now run the plan
ValueSetIterator it = q.runPlan();
System.out.println("Results for " + pquery);
AGUtils.showResults(it);
// Show some plan options
System.out.println(q.isRemoveRTF());
System.out.println(q.isReorder());
System.out.println(q.isSavedPlan());
System.out.println(q.isUseMaps());
System.out.println(q.isUseTransforms());
// Modify some plan options, run and save the new plan
q.setRemoveRTF(false);
q.setReorder(false);
q.setUseMaps(false);
q.setUseTransforms(false);
if (q.runAndSavePlan()) {
System.out.println(q.showPlan());
it = q.getResult();
System.out.println("Results for " + pquery);
AGUtils.showResults(it);
}
// Close the triple store and disconnect from the server.
ts.closeTripleStore();
ags.disable();
}
}
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