How can resultset records be restricted to certain rows?

The easy answer is "Use a JDBC 2.0 compliant driver".

With a 2.0 driver, you can use the setFetchSize() method within a Statement or a ResultSet object.

For example,

 Statement stmt = con.createStatement();
 stmt.setFetchSize(400);
 ResultSet rs = stmt.executeQuery("select * from customers");

will change the default fetch size to 400.

You can also control the direction in which the rows are processed. For instance:

 stmt.setFetchDirection(ResultSet.FETCH_REVERSE)

The driver manager usually defaults to the most efficient fetch size...so you may try experimenting with different value for optimal performance.