: select?q=*%3A*&sort=query(qf=category v='Book')desc : : but Solr returns "Can't determine a Sort Order (asc or desc) in sort".
the root cause of that error is that you don't have any whitespace between your query function and "desc" as for your broader goal: doing a straight sort on the users pref is probably not the best idea -- it's better to incorporate user prefrnces into boosting functions so you still retain the benefits of the relevancy score based on what the user searched for --- even if you know someone generally buys a lot of books, if they search for "the beatles white album" you probably don't want all the books that mention the white album, even just tangentially, to appear before the album itself. I did a talk last year on "boosting & biasing" that introduces a lot of hte concepts to think about and the basics of how to appoach problems like this in solr... https://people.apache.org/~hossman/ac2012eu/ http://vimeopro.com/user11514798/apache-lucene-eurocon-2012/video/55822630 -Hoss
