Using Sphinx with Multi-Wiki Sites
You can have sphinx instance with one sphinx.conf file, with multiple sphinx indexes defined in that file. If you do not have too much traffic, you probably want to do it this way.
Or you can have multiple sphinx instances, each with their own sphinx.conf file, each running on their own port or IP address. You probably only want to do this if you have a lot of traffic and can run each instance on a different box.