How to raise brand weight in sphinx search?

Question

Sphinx

SELECT
                  `goods`
                , `title` 
                , `brand_title`
                , `categories_name`
                , weight()
            FROM
                `index`
            WHERE
                 MATCH ('товар')
            OPTION
                ranker          =   expr(' bm25 '),
                field_weights   =   (goods=10)

How to increase the weight of all products with the 'Top' brand?

Answer 1

ranker =   expr('if(brand_title='Top',100000,1) + bm25 ')