Cassandra tag implementation with substring matching

TagManager.java

import com.datastax.driver.core.*;

import java.util.HashSet;
import java.util.Set;
import java.util.UUID;

/**
 * CREATE TABLE tag (id uuid, foreignId uuid ,name text, lowerName text,PRIMARY KEY (id) );
 *
 * create index TagNameIdx on tag(name);
 * create index TagNameLowerIdx on tag(lowerName);
 * create index TagForeignIdIdx on tag(foreignId);
 */
public class TagManager {

    private Session _session = null;

    private PreparedStatement _updateSt = null;
    private PreparedStatement _matchSt = null;


    public TagManager(Session session) {
        _session = session;
        _updateSt = session.prepare("update tag set foreignId = ?, name = ?, lowerName = ?  where id = ?");
        _matchSt = session.prepare("select id, name from tag where foreignId = ? AND lowerName >= ? and lowerName <= ? allow filtering");
    }

    public boolean add(UUID foreignId, String name) {

        BoundStatement stmnt = _updateSt.bind(foreignId, name, name.toLowerCase(), UUID.randomUUID());
        _session.execute(stmnt);

        //TODO need to really return the proper execution state. Cassandra will thrown an exception if anything goes wrong.
        return true;
    }

    public Set<String> match(UUID foreignId, String subString) {
        HashSet<String> ids = new HashSet<String>();

        // Page through results and refetch if required.
        BoundStatement stmt = _matchSt.bind(foreignId, subString.toLowerCase(), subString.toLowerCase() + Character.MAX_VALUE);
        ResultSet result = _session.execute(stmt);
        for (Row row : result.all()) {
            ids.add(row.getString("name"));
        }
        return ids;
    }
}

TagManagerTest.java

import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.Session;

import java.util.Random;
import java.util.UUID;

/**
 */

public class TagManagerTest {

    /**

     **/

    private static Random rnd = new Random();

    public static void main(String[] args) {

        Cluster cluster = Cluster.builder().addContactPoint("velum.io").build();
        try {
            Session session = cluster.connect("rm");

            TagManager mgr = new TagManager(session);
            UUID foreignId = UUID.randomUUID();
            for (int i = 0; i < 100; i++) {
                UUID uuid = UUID.randomUUID();
                mgr.add(foreignId, "tag" + i);
            }

            System.out.println("tag substr: " + mgr.match(foreignId, "tag0"));


        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            cluster.shutdown();
        }
    }

}