transactions and persitent connections

I'm a little confused/worried about database transactions, persistent connections and PHP. I am worried that if I use persistent connections it might be possible for more than one PHP script to be inside the same transaction at the same time. For example: 1- page1.php is a script that opens a persistent connection to a DB and starts a transaction. 2- User 1 goes to page1.php 3- User 2 goes to page1.php My questions: 1- is it possible that user 2 will be using the same connection as user 1? So if user 1's transaction fails so will user 2's? 2- If user 1's hits the stop button on his browser, what happens to his transaction? I assume it is stopped. But what about the connection? If user 2 gets the same connection, will his transaction fail? Thanks, Jc