WordPress Multisite database tables explained
Working with a WordPress Multisite requires a little bit more knowledge about WordPress and experience as WordPress admin than working with a single site. When you try to fix problems with your WordPress Multisite network, it is sometimes helpful to know how the database of a multisite is structured and what the differences between a Single Site database and a WordPress Multisite database are.
So let’s take a look to which database tables do we have in a single site and which we have in a multisite. We will briefly explain each of the multisite specific tables. If you need an explanation of single site tables, please read the post Database Description in the WordPress Codex.
Hint: Starting from a single site WordPress installation it is possible to switch to a WordPress Multisite through a procedure as described in the WordPress codex.
Table of Contents
WordPress single site database tablesWordPress Multisite database tablesNew tablesUpdated tablesSite Specific Tables
1. WordPress single site database tables
In a single site WordPress installation the database tables used are:
wp_commentmeta
wp_comments
wp_links
wp_options
wp_postmeta
wp_posts
wp_terms
wp_termmeta
wp_term_relationships
wp_term_taxonomy
wp_usermeta
wp_users
After we proceed with the Multisite install procedure, some of these tables are updated and other new tables are added. The remaining ones are not changed but they start to refer to the main site, while for other sites (not the main) specific ones are created.
2. WordPress Multisite database tables
So here the new situation after a Multisite install:
wp_blogs → NEW
wp_blogs_versions → NEW
wp_commentmeta → refers to main site
wp_comments → refers to main site
wp_links → refers to main site
wp_options → refers to main site
wp_postmeta → refers to main site
wp_posts → refers to main site
wp_registration_log → NEW
wp_signups → NEW
wp_site → NEW
wp_sitemeta → NEW
wp_terms → refers to main site
wp_termmeta → refers to main site
wp_term_relationships → refers to main site
wp_term_taxonomy → refers to main site
wp_usermeta → UPDATED
wp_users → UPDATED
SITE SPECIFIC TABLES → NEW, refers to other site(s) except the main one
2.1. New tables
wp_blogs: each site created is stored in that table
wp_blogs_versions: this table keeps track of the datadase version status for each site
wp_registration_log: in this table is stored the admin user created when a new site is created
wp_signups: in this table are stored the users that have registered for a site via the login registration process.
wp_site: in this table is stored the sites address
wp_sitemeta: here are tracked various site informations
2.2. Updated tables
wp_users: the list of all users of all the sites is maintained in this table
wp_usermeta: here are stored the meta data of users for all the sites
2.3. Site Specific Tables
The data of the main site is stored in existing unnumbered tables, while the data of additional sites is stored in new numbered tables.
So for the main site we have these dedicated tables:
wp_commentmeta
wp_comments
wp_links
wp_options
wp_postmeta
wp_posts
wp_terms
wp_termmeta
wp_term_relationships
wp_term_taxonomy
While, for example, when a new site is created, the site-specific tables, similar to the single site install, are created. Each set of tables for a site is created with the site ID (blog_id) as part of the table name. These are the tables that would be created for site with ID 2 :
wp_2_commentmeta
wp_2_comments
wp_2_links
wp_2_options
wp_2_postmeta
wp_2_posts
wp_2_terms
wp_2_termmeta
wp_2_term_relationships
wp_2_term_taxonomy
References:
https://codex.wordpress.org/Database_Description
https://deliciousbrains.com/wordpress-multisite-database-tour/
https://rudrastyh.com/wordpress-multisite/database-tutorial.html