A progress page with PHP + PostgreSQL

Dear all,

Permit me to gain some of your most valuable knowledge ...........

In one of our application a process takes time and as the work is in
progress we want to show our customer a progress bar
or processing page
It is some thing like this

1. Customer Clicks on button EXECUTE
2. The pgsql function is invoked
Now normally after step 2 a success page will return only after the
postgresql function finishes
but we would like as
3. Show progress of executed function
4. On Sucessfull completion Show Success page
else error page

Would be greatefull to all for any tiny clue.

Regards,
Vishal Kashyap