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I've been trying to figure out why we have the constants BLOG_ID_CURRENT_SITE and SITE_ID_CURRENT_SITE (vs. hardcoding them to be equal to 1), what exactly the differences are, and when either of them will not equal 1?

Any insight will be appreciated. Thanks in advance.

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up vote 7 down vote accepted

I addressed a similar question on StackOverflow last month.

In MultiSite, "blog" is a reference to an individual website. "Site" is a reference to a network of "blogs." In the future, there's the likelihood that WordPress will be able to power multiple networks ("site"s) in addition to its current state of multiple "blog"s.


I've done some more digging, and discovered a plug-in that easily allows you to split your multi-site installation into a multi-network one: WP Multi Network.

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So currently "site" is only ever '1'? BTW, Google failed me on finding that question via SO. – MikeSchinkel Dec 25 '10 at 0:34
the future is now - multiple networks are possible and have been ever since this was put in place. – andrea_r Dec 26 '10 at 20:40
Possible, yes. Well-understood, well-documented, and well-known, no. – EAMann Dec 27 '10 at 3:41
@andrea_r: can you share some links about that multi network feature? – hakre Dec 27 '10 at 17:35
@hakre: Also, see my update linking to a multi-network plug-in. – EAMann Dec 27 '10 at 20:43

@hakre - see the updated plugin link above. Previously, we called this multisite in wpmu. ;) that plugin was based on an old plugin for wpmu called multi-site.

We had one as well here: http://wpmututorials.com/simple-multi-site-plugin-e-book/

Actually, my wpmututorials.com site is a mapped domain in a multisite install, and my personal domain atypicalife.net is another network inside the same installation.

So yeah - I'm already using this feature and have been for a while. I talked about this in WC NYC in 2009.

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Thanks for the answer but I'm still unclear on use-cases for a Network? What value would 3 sites with 3 blogs each have over a WordPress multisite install that has just 1 site but 9 blogs? Thanks in advance. – MikeSchinkel Dec 28 '10 at 0:21
The URLs. :) If I wanted multiple mapped domains with their own sub-blogs, I'd need separate installs, or use multiple networks. – andrea_r Dec 29 '10 at 12:29

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