Re: Foreign key / performance question

On Mar 29, 2006, at 12:35 PM, Nico Callewaert wrote:

> Because from what I understand, for every foreign key, there is an
> index defined.  So, all these indexes has to be maintained.  Is
> that killing performance ?  What's the best practise : defining
> foreign keys or not ?

If your application is 100% perfect and you never do any manual
updates to the DB, then who needs FK's?

Show me that your app is 100% perfect first... which there is no way
you can do unless it is a trivial amount of code.

But just defining FK's won't define an index. You have to do that
manually else suffer performance.  However, if the referenced table
is only a few hundred rows or less, there is not much point in an
index on that column for that table.

Personally, I live by FKs since I value my data to be correct.