Order database results by bayesian rating

Posted by One Trick Pony on Stack Overflow See other posts from Stack Overflow or by One Trick Pony
Published on 2011-11-21T16:18:50Z Indexed on 2011/11/21 17:50 UTC
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I'm not sure this is even possible, but I need a confirmation before doing it the "ugly" way :)

So, the "results" are posts inside a database which are stored like this:

  • the posts table, which contains all the important stuff, like the ID, the title, the content
  • the post meta table, which contains additional post data, like the rating (this_rating) and the number of votes (this_num_votes). This data is stored in pairs, the table has 3 columns: post ID / key / value. It's basically the WordPress table structure.

What I want is to pull out the highest rated posts, sorted based on this formula:

br = ( (avg_num_votes * avg_rating) + (this_num_votes * this_rating) ) / (avg_num_votes + this_num_votes)

which I stole form here.

avg_num_votes and avg_rating are known variables (they get updated on each vote), so they don't need to be calculated.

Can this be done with a mysql query? Or do I need to get all the posts and do the sorting with PHP?

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