Magento: Where is Url rewrite index process logic stored?

I need to make product urls like this "specials/product-url-key.html" . I've found that the easiest way to do it is to simply add "specials/" at the begining of every product url rewrite in the core_url_rewrite table, request path field.

I would like to make ch开发者_运维技巧ange to the indexer process as well, so the changes will stay when its rerun, but I don't know where it is?

My Include category in product URL option is disabled.

Mage_Core_Controller_Varien_Front->dispatch()

Read more here: http://www.magento-tutorial.net/how-does-magento-url-rewriting-work/