: I don't think it can works at the index time, because I when somebody look : for a book I want to boost the search in relation with the user language : ...so I don"t think it can works, except if I didn't get it.
Hmmm... i clearly missunderstod what you were asking, you made it sound like you wnated to boost the score of documents where the string value of one field was the same as the string value of another field. If you goal is to boost the score of documents where one field contains a specific string specified by the user (ie: language) i'm not sure why you are looking at using functionqueries (and the function syntax) at all ... just add an optional "language:english" clause to your query. if you are using the dismax parser, you can do this withteh "bq" param -Hoss
