Magento Category – How to Change Category IDs and Reset Magento ID Count

I hope someone comes up with a better solution, because I'm pretty sure mine if far from being perfect, sub-optimal, and VERY hacky. Anyway, when I need the most specific category related to a product, I do something like this:

$categoryIds = $product->getCategoryIds();
$collection = Mage::getModel('catalog/category')->getCollection()
        ->addAttributeToSelect('name')
        ->addAttributeToFilter('entity_id', $categoryIds)
        ->addAttributeToFilter('is_active', 1);
$collection->getSelect()->order('level DESC')->limit(1);

$name = $collection->getFirstItem()->getName();

By sorting the categories by their level, you will get the most specific one by calling getFirstItem(). Hopefully there's a better/easier way to do it which I'm not aware of, but this one works for sure.

I should note that, in case you have 2+ categories which are on the same level, you will get only one of them, specifically the first one which appears in the collection. The result is not so easy to predict, but it was usually good enough for what I needed to do.

I was actually looking for a similar solution as I have more than 1.5 millions URL rewrites created for 35 000+ products. All of this caused by categories, subcategories but also many store views.

I just found a FREE extension that seems to work on every Magento version (confirmed up to 1.8.1 from the comments)

I'm using the latest 1.9.1 so I will have to test it out but this extension is preventing creation of all subcategories URLs, invisible and disabled products for which Magento also creates URL rewrites for.

Correction: From the comments on Magento Connect it works fine on version 1.9.1.

Please follow this link, all the details are explained in details:

http://www.dnd.fr/2012/09/magento-patch-how-to-optimize-re-index-processing-time-for-url-rewrite/

On Magento Connect:

http://www.magentocommerce.com/magento-connect/catalog/product/view/id/15074/s/dn-d-patch-index-url-1364/category/12863/