One of the things that I most enjoy about the stackexchange website is the ‘related questions’ that show up on the sidebar when I am viewing a question (or show up as I am typing my question). It is readily apparent to me that the logic being used there is much more advanced than ‘normal’ wp functionality.
I know this would be a very proprietary kind of question, but is there any available documentation on the functions being used to generate the list?
I am looking for something a bit more advanced than simply using tags for relating posts.
*I was going to use YARPP but after reading a number of comments on how that plugin can bring a site to its knees, I figured it would be best to ask first.
I know it will be not regular answer and maybe not helpful. On big site (more 16k posts) we use SOLR server with module MLT (more like this) and results are more than good.