MySQL订购非常慢

Question

我知道有很多Order By Questions与各种解决方案，但我要求的是特定于我已经在下面设置的数据结构。

我有以下2个表设置：

表设置

CREATE TABLE `record` (
    `id` INT(11) NOT NULL AUTO_INCREMENT, 
    `file_group_id` INT(11) NOT NULL, 
    `status_id` INT(11) NOT NULL, 
    `title` VARCHAR(3000) NOT NULL, 
    `date_created` DATETIME NOT NULL, 
    `user_created` INT(11) NOT NULL, 
    `publish_date` DATETIME NOT NULL, 
    PRIMARY KEY (`id`), 
    KEY `IDX_RECORD_FGID` (`file_group_id`) 
); 

CREATE TABLE `record_meta_text` (
    `id` INT(11) NOT NULL AUTO_INCREMENT, 
    `record_id` INT(11) NOT NULL, 
    `column_id` INT(11) NOT NULL, 
    `value` VARCHAR(3000) DEFAULT NULL, 
    PRIMARY KEY (`id`), 
    KEY `IDX_RMT_VALUE` (`value`(800)), 
    KEY `IDX_RMT_COL_ID` (`column_id`), 
    KEY `IDX_RMT_RECORD_ID_COL_ID` (`record_id`,`column_id`,`value`(800)) 
) 

没有订单查询通过

SELECT 
    r.title AS col_title, 
    rmt_2780.value AS col_2780, 
    rmt_2781.value AS col_2781, 
    rmt_18474.value AS col_18474 
FROM 
    record r 
INNER JOIN record_meta_text AS rmt_2780 ON rmt_2780.record_id = r.id AND rmt_2780.column_id = 2780 
INNER JOIN record_meta_text AS rmt_2781 ON rmt_2781.record_id = r.id AND rmt_2781.column_id = 2781 
INNER JOIN record_meta_text AS rmt_18474 ON rmt_18474.record_id = r.id AND rmt_18474.column_id = 18474 
WHERE 
    r.file_group_id = 2350 
    AND r.status_id = 1 
LIMIT 0, 50 

输出和解释

执行时间：0.004秒

这里是EXPLAIN输出：

id select_type table  type possible_keys       key      key_len ref        rows Extra   
------ ----------- --------- ------ --------------------------------------- ------------------------ ------- ---------------------------- ------ ------------- 
    1 SIMPLE  r   ref  PRIMARY,IDX_RECORD_FGID     IDX_RECORD_FGID   4  const       527895 Using where 
    1 SIMPLE  rmt_18474 ref  IDX_RMT_COL_ID,IDX_RMT_RECORD_ID_COL_ID IDX_RMT_RECORD_ID_COL_ID 8  file_cabinet_data.r.id,const  1 (NULL)  
    1 SIMPLE  rmt_2780 ref  IDX_RMT_COL_ID,IDX_RMT_RECORD_ID_COL_ID IDX_RMT_RECORD_ID_COL_ID 8  file_cabinet_data.r.id,const  1 (NULL)  
    1 SIMPLE  rmt_2781 ref  IDX_RMT_COL_ID,IDX_RMT_RECORD_ID_COL_ID IDX_RMT_RECORD_ID_COL_ID 8  file_cabinet_data.r.id,const  1 (NULL) 

查询与顺序按

SELECT 
    r.title AS col_title, 
    rmt_2780.value AS col_2780, 
    rmt_2781.value AS col_2781, 
    rmt_18474.value AS col_18474 
FROM 
    record r 
INNER JOIN record_meta_text AS rmt_2780 ON rmt_2780.record_id = r.id AND rmt_2780.column_id = 2780 
INNER JOIN record_meta_text AS rmt_2781 ON rmt_2781.record_id = r.id AND rmt_2781.column_id = 2781 
INNER JOIN record_meta_text AS rmt_18474 ON rmt_18474.record_id = r.id AND rmt_18474.column_id = 18474 
WHERE 
    r.file_group_id = 2350 
    AND r.status_id = 1 
ORDER BY col_2780 
LIMIT 0, 50 

输出和解释

执行时间：35.237秒

id select_type table  type possible_keys       key      key_len ref        rows Extra           
------ ----------- --------- ------ --------------------------------------- ------------------------ ------- ---------------------------- ------ ---------------------------------------------- 
    1 SIMPLE  r   ref  PRIMARY,IDX_RECORD_FGID     IDX_RECORD_FGID   4  const       527895 Using where; Using temporary; Using filesort 
    1 SIMPLE  rmt_2780 ref  IDX_RMT_COL_ID,IDX_RMT_RECORD_ID_COL_ID IDX_RMT_RECORD_ID_COL_ID 8  file_cabinet_data.r.id,const  1 (NULL)           
    1 SIMPLE  rmt_2781 ref  IDX_RMT_COL_ID,IDX_RMT_RECORD_ID_COL_ID IDX_RMT_RECORD_ID_COL_ID 8  file_cabinet_data.r.id,const  1 (NULL)           
    1 SIMPLE  rmt_18474 ref  IDX_RMT_COL_ID,IDX_RMT_RECORD_ID_COL_ID IDX_RMT_RECORD_ID_COL_ID 8  file_cabinet_data.r.id,const  1 (NULL)  

的问题及解决

所以，我的问题是，我怎么能得到这个不是由顺序采取永远。在几种情况下，我将通过条件以及声明的方式来进行多重排序。 LIMIT/OFFSET用于分页。

record表当前有1,139,119条记录。

file_meta_text表当前有7,584,428条记录。

我与基础架构和查询，但没有添加的数据（记录过多）一SQLFiddle：

http://sqlfiddle.com/#!2/6ffc3/1

任何帮助将不胜感激。

Answer 1

我可以建议使用（因为where子句）：

KEY `IDX_RECORD_FGID` (`file_group_id`,`status_id`) 

相反的：

KEY `IDX_RECORD_FGID` (`file_group_id`) 

和（因为完整的索引）

KEY `IDX_RMT_VALUE` (`value`) 

代替：

KEY `IDX_RMT_VALUE` (`value`(800)) 

但请记住，在900bytes之后，mysql不会进行索引，这就是order by的问题，这是一个使用未完全索引的字段的mysql操作。你确定你需要有长度为3000的“值”字段吗？

而且我认为，你可以使用此清洁剂查询相同的信息：

SELECT 
    r.title AS col_title, 
    rmt.value AS value, 
    rmt.column_id AS column 
FROM 
    record r 
INNER JOIN record_meta_text AS rmt ON rmt.record_id = r.id 
WHERE 
    rmt.column_id IN(2780,2781,18474) 
    AND 
    r.file_group_id = 2350 
    AND r.status_id = 1 
LIMIT 0, 50