How to read all rows from huge table?

Question

I have a problem with processing all rows from database (PostgreSQL). I get an error: org.postgresql.util.PSQLException: Ran out of memory retrieving query results.

Answer 1

I did it like below. Not the best way i think, but it works :)

    Connection c = DriverManager.getConnection("jdbc:postgresql://....");
    PreparedStatement s = c.prepareStatement("select * from " + tabName + " where id > ? order by id");
    s.setMaxRows(100);
    int lastId = 0;
    for (;;) {
        s.setInt(1, lastId);
        ResultSet rs = s.executeQuery();

        int lastIdBefore = lastId;
        while (rs.next()) {
            lastId = Integer.parseInt(rs.getObject(1).toString());
            // ...
        }

        if (lastIdBefore == lastId) {
            break;
        }
    }