>> I think this is an old question, but I want to know if it really is
>> well worth to not create some foreign keys an deal with the referential
>> integrity at application-level?????
Trust me : do it in the application and you'll enter a world of hurt. I'm
doing it with some mysql apps, and it's a nightmare ; doing cascaded
delete's by hand, etc, you always forget something, you have to modify a
million places in your code everytime you add a new table, your ORM
bloats, you get to write cleanup cron scripts which take forever to run,
your website crashes etc.