How to retrieve the large data from the database

Question

in my program, I want to operate the data retrieved from the database. but there are too many rows in the ResultSet . so when I try to get the ReusltSet from the database, the error of "java.lang.OutOfMemoryError
" will appear . because there are two million rows contained in the ResultSet, So I want to know whether there are some methods to deal with this problem.
anyone can give me some tips or recommend some papers and books to me.
thanks!!!!

Answer 1

the program is developed for the data warehourse, you know there is a large number of data in data warehourse. so I think I have to deal with the very large ResultSet in my program, this code is a example for my problem :
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class Untitled1 {
    String user = "";
    String password = "";
    public void createTable() {
        try {
            Class.forName("com.sybase.jdbc3.jdbc.SybDriver");
            System.out.println("Good to go");
            String url = "jdbc:sybase:Tds:59.64.137.240:5000/TJ";
            Connection conn = DriverManager.getConnection(url, user, password);
            System.out.println("connect successfully!");
//            Statement st1 = conn.createStatement();
            String sqlsentence2 = "SELECT DISTINCT caller FROM upcdr";
            PreparedStatement st2 = conn.prepareStatement(sqlsentence2);
            PreparedStatement st3 = conn.prepareStatement("INSERT INTO callerTable VALUES(?)");
            System.out.println("createstatement successfully!");
//            String sqlsentence1 = "CREATE TABLE callerTable (caller CHAR(18))";
//            st1.executeUpdate(sqlsentence1);
//            System.out.println(sqlsentence1);
//            st1.close();
            ResultSet rs = st2.executeQuery();
            while (rs.next()) {
                st3.setString(1, rs.getString("caller"));
                st3.executeUpdate();
                System.out.println(rs.getString("caller"));
            st2.close();
            st3.close();
        } catch (SQLException e) {
            e.printStackTrace();
            System.out.println(e.getMessage());
           System.out.println( e.getSQLState());
           System.out.println( e.getErrorCode());
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
    public static void main(String args[]) {
        Untitled1 cct = new Untitled1();
        cct.createTable();
}at here, the table "upcdr" is very large, it has two million rows. when I run this program , the error will happen. someone told me that if I use the cursor, because it will retrieve one row from the database every time, so it will not produce a very large ResultSet, then the memory would not be used out. but I am not familiar with that aspect. so I think if anyone can give me some advice.
thanks!!!!