Perfomance trics for your web application

Stéphane Thomas, from Simple Entrepreneur, has gathered a bunch of slideshares from people around town that have worked on scaling web applications:

http://www.simpleentrepreneur.com/2008/03/11/comment-gerer-la-montee-en-charge-d-une-application-web/

It's an interesting read, to complete with http://highscalability.com

file_exists - the performance killer....

I recently went into some profiling for one of our apps, because a page was taking more than two minutes to display...

I found, to my surprise, that a call to file_exists (in a loop) was taking 95 percent of that time... Wtf ??? I just cached the result to the call to gain that much time... Good to know !

As a side note, I did the profiling with the latest version of PHPEd (Nusphere), great tool.

Hierarchical structures in SQL

I wish I read this before... The "id, name, parent_id" way of storing trees in a SQL table is probably the most inneficient way to do it! There is a better way of doing things, and here it is:

http://dev.mysql.com/tech-resources/articles/hierarchical-data.html