Question

这是一个非常简单的查询：

SELECT * FROM temp_company WHERE number NOT IN (SELECT number FROM company)

之前需要15分钟，但这是在安装了缓冲池太小的Mysql，15分钟就可以了，因为这是一个月度任务。我升级到Mysql 5.7（从5.1或5.2之类的东西），原始安装是32位，我无法将innodb缓冲池大小提升到这个数据库所需的最小10gb（我已将其设置为16GB在具有32GB RAM的计算机上。我现在已经在一个月后运行此查询，并且在6小时后仍然运行。

上面的解释是：

id | select_type        | table        | partitions | type  | possible_keys | key    | key_len | ref | rows    | filtered | Extra       |
1  | PRIMARY            | temp_company |            | ALL   |               |        |         |     | 3226661 | 100.00   | Using where |
2  | DEPENDENT SUBQUERY | company      |            | index | number        | number | 33      |     | 3383517 | 100.00   | Using where |

公司和temp_company上的PRIMARY索引是id，但是数字是他们匹配的，而且两者都是KEY，但上面是否表明它没有使用temp_company表的索引？

我想要尝试的另一个逻辑查询是：

EXPLAIN SELECT tc.* FROM temp_company tc
LEFT JOIN company c on c.number = tc.number
WHERE c.number IS NULL

这同样慢，而且EXPLAIN是：

id | select_type | table | partitions | type  | possible_keys | key    | key_len | ref | rows    | filtered | Extra                                                           |
1  | SIMPLE      | tc    |            | ALL   |               |        |         |     | 3226661 | 100.00   |                                                                 |
2  | SIMPLE      | c     |            | index | number        | number | 33      |     | 3383517 | 100.00   | Using where; Ising index; Using join buffer (block nested loop) |

非常感谢任何帮助。也许Mysql改变了它找到索引的方式？

* *更新1 -------

SHOW CREATE＆＃39>：公司

   CREATE TABLE `company` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `count_telephone` mediumint(8) unsigned NOT NULL,
  `count_fax` mediumint(8) unsigned NOT NULL,
  `count_person` mediumint(8) unsigned NOT NULL,
  `person_date` date DEFAULT NULL COMMENT 'Date the company_person relation was updated',
  `count_email_address` mediumint(8) unsigned NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  `url` varchar(255) DEFAULT NULL,
  `url_date` date DEFAULT NULL,
  `url_status` smallint(5) unsigned NOT NULL DEFAULT '0' COMMENT 'Failure count for crawling the URL',
  `website_stamp_start` int(10) unsigned DEFAULT NULL,
  `website_stamp` int(10) unsigned DEFAULT NULL,
  `ch_url` varchar(255) DEFAULT NULL COMMENT 'Companies house URL',
  `keywords_stamp_start` int(10) unsigned DEFAULT NULL,
  `keywords_stamp` int(11) DEFAULT NULL,
  `number` varchar(30) CHARACTER SET ascii COLLATE ascii_bin DEFAULT NULL,
  `category` varchar(255) DEFAULT NULL,
  `status` varchar(255) DEFAULT NULL,
  `status_date` date DEFAULT NULL COMMENT 'Date the status field was updated',
  `country_of_origin` varchar(80) DEFAULT NULL,
  `dissolution_date` date DEFAULT NULL,
  `incorporation_date` date DEFAULT NULL,
  `account_ref_day` smallint(5) unsigned DEFAULT NULL,
  `account_ref_month` smallint(5) unsigned DEFAULT NULL,
  `account_next_due_date` date DEFAULT NULL,
  `account_last_made_up_date` date DEFAULT NULL,
  `account_category` varchar(255) DEFAULT NULL,
  `returns_next_due_date` date DEFAULT NULL,
  `returns_last_made_up_date` date DEFAULT NULL,
  `mortgages_num_charges` smallint(5) unsigned DEFAULT NULL,
  `mortgages_num_outstanding` smallint(5) unsigned DEFAULT NULL,
  `mortgages_num_part_satisfied` smallint(5) unsigned DEFAULT NULL,
  `mortgages_num_satisfied` smallint(5) unsigned DEFAULT NULL,
  `partnerships_num_gen_partners` smallint(5) unsigned DEFAULT NULL,
  `partnerships_num_lim_partners` smallint(5) unsigned DEFAULT NULL,
  `ext_name` varchar(255) DEFAULT NULL,
  `turnover` decimal(18,2) DEFAULT NULL,
  `turnover_date` date DEFAULT NULL,
  `trade_debtors` decimal(18,2) DEFAULT NULL,
  `other_debtors` decimal(18,2) DEFAULT NULL,
  `debtors_date` date DEFAULT NULL,
  `real_turnover_band` int(11) DEFAULT NULL,
  `est_turnover_band` int(11) DEFAULT NULL,
  `ext_address_date` date DEFAULT NULL,
  `care_of` varchar(255) DEFAULT NULL,
  `po_box` varchar(60) DEFAULT NULL,
  `line_1` varchar(255) DEFAULT NULL,
  `line_2` varchar(255) DEFAULT NULL,
  `town` varchar(60) DEFAULT NULL,
  `county` varchar(60) DEFAULT NULL,
  `country` varchar(60) DEFAULT NULL,
  `post_code` varchar(20) DEFAULT NULL,
  `DirScrapeID` int(10) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `homepage_keywords_stamp` (`keywords_stamp`),
  KEY `number` (`number`),
  KEY `url` (`url`),
  KEY `town` (`town`),
  KEY `county` (`county`),
  KEY `post_code` (`post_code`),
  KEY `name` (`name`),
  KEY `website_stamp` (`website_stamp`),
  KEY `website_stamp_start` (`website_stamp_start`),
  KEY `keywords_stamp_start` (`keywords_stamp_start`),
  KEY `turnover` (`turnover`),
  KEY `status` (`status`),
  KEY `category` (`category`),
  KEY `incorporation_date` (`incorporation_date`),
  KEY `real_turnover_band` (`real_turnover_band`),
  KEY `est_turnover_band` (`est_turnover_band`)
) ENGINE=InnoDB AUTO_INCREMENT=3706459 DEFAULT CHARSET=utf8

temp_company：

CREATE TABLE `temp_company` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  `url` varchar(255) DEFAULT NULL,
  `ch_url` varchar(255) DEFAULT NULL,
  `number` varchar(30) DEFAULT NULL,
  `category` varchar(255) DEFAULT NULL,
  `status` varchar(255) DEFAULT NULL,
  `country_of_origin` varchar(80) DEFAULT NULL,
  `dissolution_date` date DEFAULT NULL,
  `incorporation_date` date DEFAULT NULL,
  `account_ref_day` smallint(5) unsigned DEFAULT NULL,
  `account_ref_month` smallint(5) unsigned DEFAULT NULL,
  `account_next_due_date` date DEFAULT NULL,
  `account_last_made_up_date` date DEFAULT NULL,
  `account_category` varchar(255) DEFAULT NULL,
  `returns_next_due_date` date DEFAULT NULL,
  `returns_last_made_up_date` date DEFAULT NULL,
  `mortgages_num_charges` smallint(5) unsigned DEFAULT NULL,
  `mortgages_num_outstanding` smallint(5) unsigned DEFAULT NULL,
  `mortgages_num_part_satisfied` smallint(5) unsigned DEFAULT NULL,
  `mortgages_num_satisfied` smallint(5) unsigned DEFAULT NULL,
  `partnerships_num_gen_partners` smallint(5) unsigned DEFAULT NULL,
  `partnerships_num_lim_partners` smallint(5) unsigned DEFAULT NULL,
  `ext_name` varchar(255) DEFAULT NULL,
  `turnover` decimal(18,2) DEFAULT NULL,
  `turnover_date` date DEFAULT NULL,
  `trade_debtors` decimal(18,2) DEFAULT NULL,
  `other_debtors` decimal(18,2) DEFAULT NULL,
  `debtors_date` date DEFAULT NULL,
  `real_turnover_band` int(11) DEFAULT NULL,
  `est_turnover_band` int(11) DEFAULT NULL,
  `ext_address_date` date DEFAULT NULL,
  `care_of` varchar(255) DEFAULT NULL,
  `po_box` varchar(60) DEFAULT NULL,
  `line_1` varchar(255) DEFAULT NULL,
  `line_2` varchar(255) DEFAULT NULL,
  `town` varchar(60) DEFAULT NULL,
  `county` varchar(60) DEFAULT NULL,
  `country` varchar(60) DEFAULT NULL,
  `post_code` varchar(20) DEFAULT NULL,
  `sic_code` varchar(10) DEFAULT NULL,
  `DirScrapeID` int(10) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `number` (`number`),
  KEY `status` (`status`),
  KEY `name` (`name`),
  KEY `sic_code` (`sic_code`)
) ENGINE=InnoDB AUTO_INCREMENT=3297833 DEFAULT CHARSET=utf8

更新2：查询的配置文件（限制为5）

+-------------------------------+----------+
| Status                        | Duration |
+-------------------------------+----------+
| executing                     | 0.000001 |
| Sending data                  | 0.000112 |
| executing                     | 0.000001 |
| Sending data                  | 0.000111 |
| executing                     | 0.000001 |
| Sending data                  | 0.000110 |
| executing                     | 0.000001 |
| Sending data                  | 0.000110 |
| executing                     | 0.000001 |
| Sending data                  | 0.000110 |
| executing                     | 0.000001 |
| Sending data                  | 0.000111 |
| executing                     | 0.000001 |
| Sending data                  | 0.000111 |
| executing                     | 0.000001 |
| Sending data                  | 0.000112 |
| executing                     | 0.000001 |
| Sending data                  | 0.000112 |
| executing                     | 0.000001 |
| Sending data                  | 0.000112 |
| executing                     | 0.000001 |
| Sending data                  | 0.000112 |
| executing                     | 0.000001 |
| Sending data                  | 0.000112 |
| executing                     | 0.000001 |
| Sending data                  | 0.000112 |
| executing                     | 0.000001 |
| Sending data                  | 0.000113 |
| executing                     | 0.000001 |
| Sending data                  | 0.000114 |
| executing                     | 0.000001 |
| Sending data                  | 0.000114 |
| executing                     | 0.000001 |
| Sending data                  | 0.000114 |
| executing                     | 0.000001 |
| Sending data                  | 0.000115 |
| executing                     | 0.000001 |
| Sending data                  | 0.000116 |
| executing                     | 0.000001 |
| Sending data                  | 0.000115 |
| executing                     | 0.000001 |
| Sending data                  | 0.000115 |
| executing                     | 0.000001 |
| Sending data                  | 0.000116 |
| executing                     | 0.000001 |
| Sending data                  | 0.000116 |
| executing                     | 0.000001 |
| Sending data                  | 0.000115 |
| executing                     | 0.000001 |
| Sending data                  | 0.000115 |
| executing                     | 0.000001 |
| Sending data                  | 0.000116 |
| executing                     | 0.000001 |
| Sending data                  | 0.000116 |
| executing                     | 0.000001 |
| Sending data                  | 0.000117 |
| executing                     | 0.000001 |
| Sending data                  | 0.000117 |
| executing                     | 0.000001 |
| Sending data                  | 0.000117 |
| executing                     | 0.000001 |
| Sending data                  | 0.000118 |
| executing                     | 0.000001 |
| Sending data                  | 0.000118 |
| executing                     | 0.000001 |
| Sending data                  | 0.000118 |
| executing                     | 0.000001 |
| Sending data                  | 0.000118 |
| executing                     | 0.000001 |
| Sending data                  | 0.000118 |
| executing                     | 0.000001 |
| Sending data                  | 0.000118 |
| executing                     | 0.000001 |
| Sending data                  | 0.000120 |
| executing                     | 0.000001 |
| Sending data                  | 0.000120 |
| executing                     | 0.000001 |
| Sending data                  | 0.000121 |
| executing                     | 0.000001 |
| Sending data                  | 0.000123 |
| executing                     | 0.000001 |
| Sending data                  | 0.000121 |
| executing                     | 0.000001 |
| Sending data                  | 0.000120 |
| executing                     | 0.000001 |
| Sending data                  | 0.000121 |
| executing                     | 0.000001 |
| Sending data                  | 0.000121 |
| executing                     | 0.000001 |
| Sending data                  | 0.000121 |
| executing                     | 0.000001 |
| Sending data                  | 0.000122 |
| executing                     | 0.000001 |
| Sending data                  | 0.000123 |
| executing                     | 0.000001 |
| Sending data                  | 0.000124 |
| executing                     | 0.000001 |
| Sending data                  | 1.063880 |
| end                           | 0.000009 |
| query end                     | 0.000008 |
| closing tables                | 0.000009 |
| freeing items                 | 0.000007 |
| Waiting for query cache lock  | 0.000002 |
| freeing items                 | 0.000062 |
| Waiting for query cache lock  | 0.000002 |
| freeing items                 | 0.000001 |
| storing result in query cache | 0.000002 |
| cleaning up                   | 0.000028 |
+-------------------------------+----------+

Answer 1

我不知道为什么它突然运行得更慢，但我建议转换为连接，这应该会更好：

SELECT t.*
FROM temp_company t
LEFT JOIN company c ON c.number = t.number
WHERE c.number is null

这是通过连接处理not in (...)的一种相当标准的方法，并且因为不匹配的外连接在连接表的列中具有空值。

Answer 2

原来，问题是temp_company表号字段没有将ascii_bin设置为Collation，就像Company表一样。

正如MySQL论坛（http://forums.mysql.com/read.php?24,603620,603732#msg-603732）所述，具有不同排序规则或字符集的varchar字段被视为不同类型，因此无法在它们之间使用索引。

补救措施是在temp_company表的数字字段上设置相同的排序规则。然后查询需要3.3秒（使用左连接方法需要2.7秒）。

Answer 3

与以前不同，MySQL现在可能没有经过优化。你应该看看配置文件并让您的系统管理员优化它。还有，那里可能是您正在运行的Web应用程序的潜在问题和MySQL 5，例如一些较旧的插件无法正常工作。

Mysql升级后，MySQL NOT IN查询速度要慢得多

3 个答案: