I am trying to find the fastest way of getting a list/array of product id's for any given category id.
I understand this is quite fast
$category = new Varien_Object(array('id'=>$_cat));
$positions = Mage::getResourceModel('catalog/category')->getProductsPosition($category);
but there must be a way of getting the individual id's in 1 go.
So my question is: how can I retrieve an array of productids from a category id?
(Ad. where the is_anchor attribute is respected - for this Magento this means that also underlying category products are added to the collection)