我正在尝试加快以下查询的速度:
我的表有大约 400 万条记录。
EXPLAIN SELECT * FROM chrecords WHERE company_number = 'test' OR MATCH (company_name,registered_office_address_address_line_1,registered_office_address_address_line_2) AGAINST('test') LIMIT 0, 10;
+------+-------------+-----------+------+------------------+------+---------+------+---------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+-----------+------+------------------+------+---------+------+---------+-------------+
| 1 | SIMPLE | chrecords | ALL | i_company_number | NULL | NULL | NULL | 2208348 | Using where |
+------+-------------+-----------+------+------------------+------+---------+------+---------+-------------+
1 row in set (0.00 sec)
我使用以下方法创建了两个索引:
ALTER TABLE `chapp`.`chrecords` ADD INDEX `i_company_number` (`company_number`);
ALTER TABLE `chapp`.`chrecords`ADD FULLTEXT(
`company_name`,
`registered_office_address_address_line_1`,
`registered_office_address_address_line_2`
);
但是如何“结合”这两个索引呢?由于上述查询需要 15 秒以上的时间来执行(仅使用一个索引)。
整个表定义:
CREATE TABLE `chapp`.`chrecords` (
`id` INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
`company_name` VARCHAR(100) NULL,
`company_number` VARCHAR(100) NULL,
`registered_office_care_of` VARCHAR(100) NULL,
`registered_office_po_box` VARCHAR(100) NULL,
`registered_office_address_address_line_1` VARCHAR(100) NULL,
`registered_office_address_address_line_2` VARCHAR(100) NULL,
`registered_office_locality` VARCHAR(100) NULL,
`registered_office_region` VARCHAR(100) NULL,
`registered_office_country` VARCHAR(100) NULL,
`registered_office_postal_code` VARCHAR(100) NULL
);
ALTER TABLE `chapp`.`chrecords` ADD INDEX `i_company_name` (`company_name`);
ALTER TABLE `chapp`.`chrecords` ADD INDEX `i_company_number` (`company_number`);
ALTER TABLE `chapp`.`chrecords` ADD INDEX `i_registered_office_address_address_line_1` (`registered_office_address_address_line_1`);
ALTER TABLE `chapp`.`chrecords` ADD INDEX `i_registered_office_address_address_line_2` (`registered_office_address_address_line_2`);
ALTER TABLE `chapp`.`chrecords`ADD FULLTEXT(
`company_name`,
`registered_office_address_address_line_1`,
`registered_office_address_address_line_2`
);
最佳答案
(
SELECT *
FROM chrecords
WHERE company_number = 'test'
ORDER BY something
LIMIT 10
)
UNION DISTINCT
(
SELECT *
FROM cbrecords
WHERE MATCH (company_name, registered_office_address_address_line_1,
registered_office_address_address_line_2)
AGAINST('test')
ORDER BY something
LIMIT 10
)
ORDER BY something
LIMIT 10
注意事项:
- 不需要外部
SELECT
- 明确地说出
DISTINCT
(默认)或ALL
(更快),这样您就会知道您考虑过是否需要重复数据删除,而不是速度。< - 没有
ORDER BY
的LIMIT
意义不大 - 但是,如果您只想查看一些行,您可以删除
ORDER BYs
。 - 是的,
ORDER BY
和LIMIT
需要在外部重复,这样您才能获得正确的顺序并限制为 10。
如果你需要一个OFFSET
,里面需要一个完整的计数,比如说LIMIT 50
5页,然后外面需要跳到第5页: 限制 40,10
。
关于普通列和全文列的MySQL索引,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/43706120/