This example shows that only one fulltext index is needed.

Here are queries from that example:

    ALTER TABLE products ADD FULLTEXT(title, sdescription, ldescription)

    SELECT *,
    MATCH(`title`) AGAINST ('+iphone +case +4s' IN BOOLEAN MODE) * 10 as rel1,
    MATCH(`sdescription`) AGAINST ('+iphone +case +4s' IN BOOLEAN MODE) * 3 as rel2,
    MATCH(`ldescription`) AGAINST ('+iphone +case +4s' IN BOOLEAN MODE) as rel3,
    FROM products
    WHERE MATCH (title, sdescription, ldescription) 
      AGAINST ('+iphone +case +4s' IN BOOLEAN MODE)
    ORDER BY (rel1)+(rel2)+(rel3) DESC;
And this answer suggests that three fulltext indexes are needed to do the same. <>

  I want to make one column more valuable than others like it's been done in the above query. I'm confused how many indexes are needed for that, one or three?
I asked this question on stackoverflow but not answer yet.