Here is a naughty bit I discovered a few days ago.

You probably already know your can make a model in cake "dependable". When a model is dependable it means that when you delete stuff from model A, related stuff in model B will be automagically deleted by cake.

Let's say A=DocumentHeader and B=DocumentItem, B being dependable on A. If you delete a document, cake will automagically delete all the items in B related to that document. But, what's not obvious is that cake will delete items in B one by one. Well, I don't know, maybe it's obvious to some, but it's not really obvious to me. So if you have 200.000 document items, you'll have to wait a while before cake executes delete from ... for each and every one of those.

Last week, I just happened to have such a relation and I wasn't aware of the above fact. Let's just say it was slow. Painfully slow. Nasty.

Since people don't like painfully slow and nasty things (except sex of course), we need to fix that. Luckily for us, there is a built-in parameter which tells cake to delete all the related stuff with a single query. In other words, cake will use deleteAll() to delete stuff in the related model.

Solution? Just add "exclusive":

class DocumentHeader
{
    var $hasMany = array
        (
            'DocumentItem' => array
            (
                'className' => 'DocumentItem',
                'foreignKey' => 'document_id',
                'dependent' => true,
                'exclusive' => true, // voila!
            )
        );
}

Honestly, that's all you need to do to get a kick-ass performance boost. It's so good that I wonder why is this not the default behaviour?

Anyway, if you don't have any special requirements in before/after delete operations in your DocumentItem, this is the only way not to shoot yourself in the genitals. Or foot. Whichever you prefer.

Happy baking!