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.

  • Good question... but it looks to me like the "related posts" in the sidebar are just found through a tag intersection. The "possibly related" questions that show up on adding a new question is a little more advanced. Asking "how that's done" could maybe be a question for meta, but I think people here could reverse-engineer it and suggest WP-specific solutions, which would probably be more fun. Mar 2, 2011 at 21:21
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    YARPP has made great strides in speed improvements, as well as ensuring compatibility with popular caching plugins, such as W3 Total Cache and WP Super Cache. You might want to give it a try. Apr 8, 2011 at 20:49
  • I second John. YARPP had long fixed performance issues and it is both great at finding related posts and presenting them (I use widget with custom YARPP template myself).
    – Rarst
    Apr 8, 2011 at 21:03

1 Answer 1


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.

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