Problem in loading jsp page

Question

Hi ,
I'm facing a problem in displaying a JSP page . I'm displaying records from the database on the page . I want to display only 20 records at a time . I have given the navigation facility for previous,first ,last ,next etc.
I'm getting all the records at once and displaying them at once . But , I show only 20 records at a time ,hiding the remaining records .
This works fine for less no . of records but for more records ,say 2000-3000 records , it gets quite slow as expected .
I don't want to fire the query again .
Is there any other way possible using this technique .
It's very urgent . So kindly help .
Thanks.

Answer 1

Just get a scrollable ResultSet with the row amount for 1 page, e.g.
      * Returns a result set for the given query, that is read only and scrollable
     * (cursor can move forward and backward). The default fetch size is used and
     * can be changed anytime by calling resultSet.setFetchSize(newFetchSize).
     * <p>
     * Note: be sure that the used JDBC driver supports scrollable result sets via
     * <code>DatabaseMetaData.supportsResultSetType(ResultSet.TYPE_SCROLL_SENSITIVE)</code>
      * @param select SQL select query.
     * @param fetchSize Number of rows to prefetch.
      * @return Scrollable, read-only result set.
    private ResultSet getScrollableResultSet(String select, int fetchSize) {
        ResultSet result = null;
        if (select != null) {
            try {
//TYPE_SCROLL_SENSITIVE can throw SQLException "Unsupported syntax for refreshRow()" with the
//current ORACLE driver (8.1.7.0.0).
//                Statement stmt = createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
                Statement stmt = createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
                int maxRows = stmt.getMaxRows();
                if (fetchSize < 0 || fetchSize > maxRows) {
                    fetchSize = 0; //ignore fetch size
                stmt.setFetchSize(fetchSize);
                long t = System.currentTimeMillis();
                result = stmt.executeQuery(select);
                logger.debug(select + (" ("+(System.currentTimeMillis() - t)+")"));
                if (result == null) {
                    stmt.close();
            } catch (SQLException sqle) {
                logger.error("Error getting scrollable ResultSet for '"+select+"'.", sqle);
                throw new BavException(sqle);
        return result;
    }//getScrollableResultSet()and fetch the next/previous page records via the resultSets next()/previous() methods. But beware that the SQL statement doesn't use an ORDER BY or GROUP BY that needs to fetch all rows anyway.