Can I improve my movie selecting SQL query - mysql

Question

I've created a database to store movies data. My tables are the following:
movies:
CREATE TABLE IF NOT EXISTS `movies` (
`movieId` int(11) NOT NULL AUTO_INCREMENT,
`imdbId` varchar(255) DEFAULT NULL,
`imdbRating` float DEFAULT NULL,
`movieTitle` varchar(255) NOT NULL,
`movieLength` varchar(255) NOT NULL,
`imdbRatingCount` varchar(255) NOT NULL,
`poster` varchar(255) NOT NULL,
`year` varchar(255) NOT NULL,
PRIMARY KEY (`movieId`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;
I have a table in which i store movie actors:
CREATE TABLE IF NOT EXISTS `actors` (
`actorId` int(10) NOT NULL AUTO_INCREMENT,
`actorName` varchar(255) NOT NULL,
PRIMARY KEY (`actorId`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;
And one other in which i store the relation between the movies and actors: (movieActor)
CREATE TABLE IF NOT EXISTS `movieActor` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`movieId` int(10) NOT NULL,
`actorId` int(10) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
Now when i want to select a list of movies in which are the selected actors my query is:
SELECT *
FROM movies m inner join
(SELECT movieId FROM movieActor WHERE actorId IN(1,2,3) GROUP BY movieId having count(*) = 3) ma ON m.movieId = ma.movieId
WHERE imdbRating IS NOT NULL ORDER BY imdbRating DESC
This is working perfectly, but i don't know that this is the optimal table structure and query to accomplish this. Are there any better table structure to store data or query the list?

Answer 1

First of all, use indexes on your tables. In my opinion it should be useful to have 3 indexes on movieActor. MovieId - ActorID - MovieIdActorId.
Second try tu use foreign keys. These help to identify the best execution plan for your dbs.
Third try to avoid generating temp tables in your execution plan of your query. Subselects often creates temp tables which are used when the database has to temporarily save something in the RAM. To check this, write EXPLAIN in front of goer query.
I would write it like this:
SELECT m.*, movieActor
FROM movies m inner join
movieActor ma ON m.movieId = ma.movieId
WHERE imdbRating IS NOT NULL
and actorId IN(1,2,3)
GROUP BY movieId
having count(*) = 3)
ORDER BY imdbRating DESC
(Not tested)
Just try to optimize it with the EXPLAIN keyword. It also can help you to create the right indexes.