Text database instead of MySql (Recommendations / Advise also welcome)

Hey, I have been asked to make a site that would be pretty high traffic... problem is, no MySql. Although i have messed around with php's file and directory commands I have never really made anything "really big" using them, I always used MySql, here I dont have that choice as the server itself does not have MySql installed. After a bit of seaching on the SEs I found quite a few links to have text databases and have kind of settled on this one: PHP Text DB (http://www.c-worker.ch/txtdbapi/index_eng.php) If anybody has any experience using the above, or would rather recommend another I would appreciate a reply from you. As usual; any advise / links would also be appreciated. Thanks, Ryan