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这让我发疯了。我已经使用 imdbpy 转储了 imdb db。我正在尝试查找通过电影的第一个字母提供演员数据的美国电影。

下面是一个查询示例，它在没有 acto 数据的情况下获取电影。这运行得非常快：

SELECT DISTINCT title.id,title.title,title.production_year
FROM  title

INNER JOIN movie_info ON
(movie_info.movie_id =  title.id
AND
movie_info.info_type_id = 8
AND
movie_info.info =  'USA') 

WHERE  title LIKE  'a%'
AND  title.kind_id =  1
LIMIT 75

演员表数据存储在一个名为cast_info并包含大约 2200 万条记录的单独表中。该nr_order列包含电影中演员的演职员表顺序。例如，汤姆汉克在《阿甘正传》中是 1。每个 . 通常有几十行movie_id。

因此，要检查参与者数据是否可用，应该至少有一行对于该特定的movie_id. 如果 a 中的所有值都nr_order为movie_id空，则它不包含我需要的数据。

要尝试获取此信息，请使用以下查询：

SELECT DISTINCT title.id,title.title,title.production_year
FROM  title

INNER JOIN movie_info ON
(movie_info.movie_id =  title.id
AND
movie_info.info_type_id = 8
AND
movie_info.info =  'USA') 

INNER JOIN cast_info ON 
(cast_info.movie_id = title.id
AND
cast_info.nr_order = 1)

WHERE  title LIKE  'a%'
AND  title.kind_id =  1
LIMIT 75

由于某种原因，查询变得非常慢。第一个查询需要 0.3-.7 秒，第二个查询大约需要 6-10 秒。我在cast_info. nr_order但这没有帮助。

解释输出：

+----+-------------+-----------+-------+--------------------------------------------------+-------------------+---------+--------------+-------+-----------------------------+
| id | select_type | table     | type  | possible_keys                                    | key               | key_len | ref          | rows  | Extra                       |
+----+-------------+-----------+-------+--------------------------------------------------+-------------------+---------+--------------+-------+-----------------------------+
|  1 | SIMPLE      | title     | range | PRIMARY,title_idx_title,fk_kind_type_id_4        |  title_idx_title  | 257     | NULL         | 132801| Using where; Using temporary|
|  1 | SIMPLE      | movie_info| ref   | ovie_info_idx_mid,info_type_id movie_info_idx_mid| movie_info_idx_mid| 4       | imdb.title.id| 4     | Using where; Distinct       |
|  1 | SIMPLE      | table1    | ref   | cast_info_idx_mid,nr_order                       | cast_info_idx_mid | 4       | imdb.title.id| 12    | Using where; Distinct       |
+----+-------------+-----------+-------+--------------------------------------------------+-------------------+---------+--------------+-------+-----------------------------+

任何想法都会非常有帮助！

编辑：从第一个查询中解释

+----+-------------+-----------+-------+--------------------------------------------------+-------------------+---------+--------------+-------+-----------------------------+
| id | select_type | table     | type  | possible_keys                                    | key               | key_len | ref          | rows  | Extra                       |
+----+-------------+-----------+-------+--------------------------------------------------+-------------------+---------+--------------+-------+-----------------------------+
|  1 | SIMPLE      | title     | range | PRIMARY,title_idx_title,fk_kind_type_id_4        |  title_idx_title  | 257     | NULL         | 132801| Using where; Using temporary|
|  1 | SIMPLE      | movie_info| ref   | ovie_info_idx_mid,info_type_id movie_info_idx_mid| movie_info_idx_mid| 4       | imdb.title.id| 4     | Using where; Distinct       |
+----+-------------+-----------+-------+--------------------------------------------------+-------------------+---------+--------------+-------+-----------------------------+
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1 回答 1

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由于您只关心是否有可用的演员表信息，您可以尝试使用EXISTS：

SELECT DISTINCT title.id,title.title,title.production_year
FROM  title

INNER JOIN movie_info ON
(movie_info.movie_id =  title.id
AND
movie_info.info_type_id = 8
AND
movie_info.info =  'USA') 

WHERE  title LIKE  'a%'
AND  title.kind_id =  1
AND EXISTS(SELECT 1 FROM cast_info WHERE cast_info.movie_id = title.id AND cast_info.nr_order IS NOT NULL)
LIMIT 75

我不确定您的行为的确切解释，但DISTINCT可能会在连接上有很多行 - 或者连接产品上至少有很多行 - 做一些有趣的事情 - （注意 Distinct 被应用于 cast_info 表中解释）。

于 2012-10-26T17:39:05.817 回答