Mysql Perfomance with complicated relations and big db size

[roy simkes]

Hi,

I'm curious to learn how is mysql's performance with complicated relations(a relation b, b relation c,c relation d, and go on). How problems can I encounter in a big sized database with lots (I really mean 'lots') of relations inside. What kind of things can happen or doesn't happen (like broken relations and non working operations which should work).

How is the mysql's performance and possible bugs or problems that I can encounter with mysql while using it in a big project (a very big one!). What are the differences of InnoDB and MyISAM in a big project. What are they advantages? Why should I choose one of them for a big project?

I know that this the mysql's offical site and no one wants to say a bad thing about it's product but please be as honest as you can.

Thank you for your time, interest and honesty.

Roy Simkes