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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