Converting a ResultSet to XML (mysql) - very slow - need some criticism

Question

Preface:
I have some data being inserting into a mySQL table every 5 minutes. Currently, there are about 275 rows. Each row has 26 (TEXT) columns, the data in those columns is no longer than 10-15 characters.
I am using the following code to turn this data into XML which is then, through a servlet, output on a webserver. With 275 rows, this is taking around 3-4 minutes to generate the XML file. I am worried that in a week from now when the data is over 2,000 rows it will exponentially decrease in speed. Can someone give me a better route so this will run faster?
         String xml = "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n\n";
       String SQLCommand = "select * from "+getDataId()+";";
       try{
            Statement stmt;     
            ResultSet rs;
           String url = "jdbc:mysql://"+getIBoxIp()+":"+getDbPort()+"/"+getDbName();          
           Connection con = DriverManager.getConnection(url,getDbUsername(), getDbPassword());                     
                stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
                rs = stmt.executeQuery(SQLCommand);
                while(rs.next()){
                  xml += "\n<row>";
                  ResultSetMetaData md = rs.getMetaData();
                  for(int i = 1; i < md.getColumnCount() + 1; i++){
                       xml += "\n\t<" + md.getColumnName(i) + ">" + rs.getString(i) + "</" + md.getColumnName(i) + ">";
                  xml += "\n</row>\n";
                System.out.println("@@mysql> XMLSQLCommand > " + SQLCommand);          
           con.close();     
           return xml;
       }catch(Exception ex)
            System.out.println("@@mysql> SQLCommand Failed > " + SQLCommand + "\n@@mysql> Exception > " + ex.getMessage() + "");
            return xml;
       }Again, with 275 rows, I'm getting about 250 KB of data in the resulting XML file with a 3-5 minute parsing/generation time.
Thanks in advance!!!
Edited by: bergy on Sep 21, 2007 8:46 AM added code tags

Answer 1

No, it's a good question. The page I linked to does say
"Instead of XMLWriter, this driver uses David Megginson�s other public domain writer program, DataWriter..."
So yeah, trying to track down Megginson's code might not be such a good idea. But the sentence quoted does suggest what should be used instead: XMLWriter. Which implies that XMLWriter was mentioned somewhere earlier in the book.
So, following the "Prev" links to previous pages, eventually I found XMLWriter discussed a couple of pages earlier, where it says
"More specifically, I�m going to use David Megginson�s public domain com.megginson.sax.XMLWriter class."
I don't really find this very satisfactory as advice for beginners, so I somewhat regret doing that. It's a long time since I looked at that page myself. But it does have a link pointing to http://www.megginson.com/downloads/, where it is possible to download the Java version of XMLWriter. I'm not sure if the OP is comfortable with using downloaded software, but that download is the simplest possible Java download so it might be a good place to start.
You could recommend using a DOM strategy, and JDOM might be a good choice, but if you can just generate the XML straight from your input, it's a better strategy to do that rather than building a DOM tree in memory and then serializing it, in my opinion.