The going through the mu functions source I come across references to two different ids for sub-blogs - site id and blog ids. In what context is each used?
- site_id = the ID of the parent site (the domain, eg. wordpress.com)
- blog_id = the ID of the parent site's blog(s) (usually sub-domains, eg mary.wordress.com)
In a Multisite install (and also since WordPress 3), you can have a several blogs (identified in the database model by
blog_id) within one site (identified in the database model by
The thing that I found confusing in this context, though, is that most of WordPress code and documentation will use a terminology that differs from the database model. They refer to a blog using the word site, and to a site using the word network.
For example, this section of the Codex refers to the Site URL (as defined in the
WP_SITEURL constant), which really is the URL of the blog URL in multisite context.