Which hierarchical model for menu and categories is used in CMS like Joomla or WP?

database-design, hierarchical-data, joomla, wordpress

Solution

Joomla is using nested sets for multiple things, including menu items and categories.

Wordpress seems to use a rather unusal system, storing its menu items along with other things in its "terms" table. I can only find a "parent" field there, so I'm assuming it's just simply storing the id of the parent item to model hierarchical menus. I haven't worked with Wordpress though.

Problem

Adjaceny or Nested sets model or something else? I am interested in CMS like Joomla or WordPress and how they deal with menus, categories and other hierarchical datas that are stored in db. Thanks in advance.

Original source