// DBRatingsSource.java

import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class DBRatingsSource {
    public DBRatingsSource() throws SQLException {
        DBConnection myConn = new DBConnection();

        myConn.getConn().setReadOnly(true);  // Optimization hint
        // Tell MySQL to return results one row at a time
        Statement stmt = myConn.getConn().createStatement(
                java.sql.ResultSet.TYPE_FORWARD_ONLY,
                java.sql.ResultSet.CONCUR_READ_ONLY);
        stmt.setFetchSize(Integer.MIN_VALUE);

        ResultSet rs = stmt.executeQuery("SELECT userId, movieId, rating FROM user_rating_pairs");

        // ** BUG: myConn is garbage collected, and the DB connection is closed
        // during this long loop:
        //int i = 0;
        while (rs.next()) {
            //System.out.println(i++);
        }
        
        rs.close();
        // Uncommenting this makes the bug go away, because myConn is
        // not garbage collected
        //System.out.println(myConn);
    }

    public static void main(String args[]) throws java.sql.SQLException {
        DBRatingsSource source = new DBRatingsSource();
    }
}