In my previous post I took you through all the tables of the WordPress database for a single site install. In this tour I will be looking at the tables and database changes for a Multisite installation of WordPress.
When a WordPress site is converted to a Multisite install, a “network” of subsites is created. The existing site is converted to the first subsite in the network. The database classes the network itself as a site (wp_site), and each subsite as a blog (wp_blogs).
Certain tables are used only by a subsite, and a new set of tables are created every time a site is added to the network. Each set of tables is differentiated by the blog_id for the subsite used in the table prefix. e.g. `wp_2_posts`. The following tables are subsite specific: