(
    SELECT DISTINCT f_topics.*, f_posts.id AS postID,
    (MATCH (f_posts.text) AGAINST ('%1\$s')) AS score
    FROM f_topics
    INNER JOIN f_posts ON f_posts.topicId = f_topics.id
    WHERE MATCH(f_posts.text) AGAINST ('%1\$s')
)
UNION
(
    SELECT DISTINCT f_topics.*, 0 AS postID,
    (MATCH (f_topics.title) AGAINST ('%1\$s')*2) AS score
    FROM f_topics
    WHERE MATCH(f_topics.title) AGAINST ('%1\$s')
)
ORDER BY score DESC
LIMIT 0,20