Multisite and plugins options

Question

I need more information about get_site_option(), update_site_option() and add_site_option(). In codex they say it's the same as single install except that in multisite, it returns the network-wide option.

Ok but I get confused on the this point : does it mean once network-wide option is set this option is the same in all sites? Or is it overriden per each site?

I mean if I do this :

 update_site_option('option_group', 'default_options());// default_options() returns an array of default options

Where will it save datas? And will each site get its own values for options after?

It's quite unclear for me any hint will be cool.

Answer 1

Back when Multisite first appeared, there were multiple blogs in a single site. The *_site_option functions are from that older Multisite era.

Now in current Multisite you have multiple sites in a network, so the meaning of "site" has made a confusing change.

In the context of these functions, think of them as network functions and it may make more sense. They create and update options which are not associated to a particular site in your network, but are global to the whole network.

If you want unique, per-site options, use the regular add_option, update_option, and get_option.