Any way to optimize this mysql query?

Question

This is the query. Im mostly interested if there is a better way to grab the stuff I use GROUP_CONCAT for, or if thats a fairy good way of grabbing this data. I then explode it, and put the ids/names into an array, and then use a for loop to echo them out.

SELECT 
    mov_id, 
    mov_title, 
    GROUP_CONCAT(DISTINCT categories.cat_name) as all_genres, 
    GROUP_CONCAT(DISTINCT cat_id) as all_genres_ids,  
    GROUP_CONCAT(DISTINCT case when gen_dominant = 1 then gen_catid else 0 end) as dominant_genre_ids, 
    GROUP_CONCAT(DISTINCT actors.act_name) as all_actors, 
    GROUP_CONCAT(DISTINCT actors.act_id) as all_actor_ids, 
    mov_desc, 
    mov_added, 
    mov_thumb, 
    mov_hits, 
    mov_numvotes, 
    mov_totalvote, 
    mov_imdb, 
    mov_release, 
    mov_html, 
    mov_type,
    mov_buytickets,
    ep_summary,
    ep_airdate,
    ep_id,
    ep_hits,
    ep_totalNs,
    ep_totalRs,
    mov_rating,
    mov_rating_reason,
    mrate_name,
    dir_id, 
    dir_name
FROM movies
LEFT JOIN _genres
    ON movies.mov_id = _genres.gen_movieid
LEFT JOIN categories
    ON _genres.gen_catid = categories.cat_id
LEFT JOIN _actors
    ON (movies.mov_id = _actors.ac_movid)
LEFT JOIN actors
    ON (_actors.ac_actorid = actors.act_id AND act_famous = 1)
LEFT JOIN directors
    ON movies.mov_director = directors.dir_id
LEFT JOIN movie_ratings
    ON movies.mov_rating = movie_ratings.mrate_id
LEFT JOIN episodes
    ON mov_id = ep_showid AND ep_season = 0 AND ep_num = 0
WHERE mov_id = *MOVIE_ID* AND mov_status = 1 
GROUP BY mov_id

EXPLAIN of the query is here

alt text http://www.krayvee.com/o2/explain.gif

Answer 1

Personally, I would try to break the query up into multiple queries. Mostly I would recommend removing the Actor and Genre Joins so that you can get rid of all those group_concat functions. Then do separate queries to pull this data out. Not sure if it would speed things up, but it's probably worth a shot.

Answer 2

You've basically done a Cartesian product between genres, actors, directors, movie_ratings and episodes. That's why you have to use DISTINCT inside your GROUP_CONCAT(), because the pre-grouped result set has a number of rows equal to the product of the number of matching rows in each related table.

Note that this query wouldn't work at all in SQL, except that you're using MySQL which is permissive about the single-value rule.

Like @Kibbee, I usually recommend to run separate queries in cases like this. It's not always better to run a single query. Try breaking up the query and doing some profiling to be sure.

PS: What? No _directors table? So you can't represent a move with more than one director? :-)