使用该索引，当我运行它通过探查

Question

在我的慢查询日志，我看到这样

 
# Time: 121107 16:34:02 
# User@Host: web_node[web_node] @ localhost [127.0.0.1] 
# Thread_id: 34436186 Schema: test_db Last_errno: 0 Killed: 0 
# Query_time: 1.413751 Lock_time: 0.000222 Rows_sent: 203 Rows_examined: 203 Rows_affected: 0 Rows_read: 203 
# Bytes_sent: 7553 Tmp_tables: 0 Tmp_disk_tables: 0 Tmp_table_sizes: 0 
# InnoDB_trx_id: 9B04384 
SET timestamp=1352334842; 
SELECT id, email FROM test_data WHERE id IN (13089576,3002681,3117763,1622233,2941590,12305279,1732672,2446772,3189510,13084725,4943929,5855071,6572137,2266261,3003496,2024860,3336832,13758671,6477694,1796684,13001771,4690025,1071744,1017876,5175795,795988,1619821,2481819,2941090,4770802,13438250,3254708,2323402,526303,13219855,3313573,3190479,1733761,3300577,2941758,6474118,1733379,11523598,4205064,6521805,2492903,1860388,3337093,5205317,1213970,5442738,12194039,1214203,12970536,3076611,3126152,3677156,5305021,2751587,4954875,875480,2105172,5309382,12981920,5204330,13729768,3254503,5030441,2680750,590661,1338572,7272410,1860386,2567550,5434143,1918035,5329411,1683235,3254119,5175784,1855380,3336834,2102567,4749746,37269,3207031,6464336,2227907,2713471,3937600,2940442,2233821,5619141,5204711,5988803,5050821,10109926,5226877,5050275,1874115,13677832,5338699,2423773,6432937,6443660,1990611,6090667,6527411,6568731,3254846,3414049,2011907,5180984,12178711,8558260,3130655,5864745,2059318,3480233,2104948,2387703,1939395,5356002,2681209,1184622,1184456,10390165,510854,7983305,795991,2622393,4490187,9436477,5356051,2423464,5205318,1600499,13623229,3255205,12200483,6477706,3445661,5226284,1176639,13760962,2101681,6022818,12909371,1732457,2377496,7260091,12191702,2492899,2630691,13047691,1684470,9382108,2233737,13117701,1796698,2535914,4941741,4565958,1100410,2321180,13080467,813342,4563877,4689365,2104756,1102802,2714488,3188947,1599770,1558291,5592740,5233428,5204830,1574452,3188956,13693326,2102349,3704111,1748303,790889,9323280,4741494,2387900,5338213,3583795,2283942,3189482,3002296,4490123,3585020,962926,3481423,1600920,1682364,4693123,6487778,2677582,2377195);

慢查询当我使用运行通过探查慢查询不慢的MySQL慢查询SQL_NO_CACHE它看起来说

 
203 rows in set (0.03 sec) 

show profile for query 33; 
+----------------------+----------+ 
| Status    | Duration | 
+----------------------+----------+ 
| starting    | 0.000187 | 
| checking permissions | 0.000012 | 
| Opening tables  | 0.000034 | 
| System lock   | 0.000016 | 
| init     | 0.000087 | 
| optimizing   | 0.000024 | 
| statistics   | 0.028694 | 
| preparing   | 0.000074 | 
| executing   | 0.000005 | 
| Sending data   | 0.001596 | 
| end     | 0.000009 | 
| query end   | 0.000008 | 
| closing tables  | 0.000014 | 
| freeing items  | 0.001600 | 
| logging slow query | 0.000007 | 
| cleaning up   | 0.000011 | 
+----------------------+----------+ 

当我运行解释说

 
+----+-------------+------------------+-------+------------------+----------+---------+------+------+--------------------------+ 
| id | select_type | table   | type | possible_keys | key  | key_len | ref | rows | Extra     | 
+----+-------------+------------------+-------+------------------+----------+---------+------+------+--------------------------+ 
| 1 | SIMPLE  | test_data  | range | PRIMARY,id_email | id_email | 4  | NULL | 203 | Using where; Using index | 
+----+-------------+------------------+-------+------------------+----------+---------+------+------+--------------------------+ 

查询创建表的外观就像

 
CREATE TABLE `test_data` (
    `id` int(11) NOT NULL AUTO_INCREMENT, 
    `email` varchar(254) DEFAULT NULL, 
    `domain` varchar(254) DEFAULT NULL, 
    `age` smallint(6) DEFAULT NULL, 
    `gender` tinyint(1) DEFAULT NULL, 
    `location_id` int(11) unsigned DEFAULT NULL, 
    `created` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00', 
    `unistall_date` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00', 
    `subscription_date` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00', 
    `active` tinyint(1) DEFAULT '1', 
    PRIMARY KEY (`id`), 
    UNIQUE KEY `email` (`email`), 
    KEY `domain` (`domain`), 
    KEY `id_email` (`id`,`email`), 
    KEY `email_id` (`email`,`id`) 
) ENGINE=InnoDB AUTO_INCREMENT=13848530 DEFAULT CHARSET=utf8 

有是获取定期运行来自电子邮件地址列表中选择ID和电子邮件，因此该电子邮件，ID键，电子邮件地址必须是唯一的，因此为什么这是一个独特的关键另一个查询。该表只有~14M行

我想也许是索引，其中大到内存和交换，但盒子有8演唱会的内存。

 
SELECT table_schema "Data Base Name", SUM(data_length + index_length)/1024/1024 "Data Base Size in MB", SUM(index_length)/1024/1024 "Index Size in MB" FROM information_schema.TABLES GROUP BY table_schema; 
+--------------------+----------------------+------------------+ 
| Data Base Name  | Data Base Size in MB | Index Size in MB | 
+--------------------+----------------------+------------------+ 
| metrics   |  3192.50000000 | 1594.42187500 | 
| data    |  8096.48437500 | 5639.51562500 | 
| raw_data   |  6000.35937500 |  745.07812500 | 
| information_schema |   0.00878906 |  0.00878906 | 
| mysql    |   0.04319191 |  0.04101563 | 
| performance_schema |   0.00000000 |  0.00000000 | 
+--------------------+----------------------+------------------+ 

在my.cnf文件中设置innodb_file_per_table = 1似乎解决了这个问题。

这改善了执行时间，我的理解是每个表具有单个文件意味着磁盘针不需要移动这么大的距离。

问题

1. 如果查询可以使用索引来评估为什么设置innodb_file_per_table = 1提高性能
2. 为什么心不是查询速度慢，当它运行的探查不使用缓存？
3. 我的主键应该是（id，email）吗？

更新

本来没有的/etc/my.cnf文件，然后创建一个具有以下

 
[mysqld] 
server-id=1 
max_connections=1500 
key_buffer_size=50M 
query_cache_limit=16M 
query_cache_size=256M 
thread_cache=16 
table_open_cache=4096 
sort_buffer_size=512K 
join_buffer_size=8M 
read_buffer_size=8M 
skip_name_resolve=1 
thread_cache_size=256 
innodb_buffer_pool_size=6G 
innodb_buffer_pool_instances=1 
innodb_thread_concurrency=96 
innodb_additional_mem_pool_size=32M 
innodb_log_buffer_size=8M 
innodb_flush_log_at_trx_commit=0 
innodb_log_file_size=256M 
innodb_flush_method=O_DIRECT 
innodb_file_per_table=1 
net_read_timeout=15 
net_write_timeout=30 
log-bin=mysql-bin 
sync_binlog=0 
datadir=/var/lib/mysql 

Answer 1

你有太多的数据为您innodb_log_buffer。

什么是价值：

innodb_buffer_pool_size 
innodb_log_file_size 

所有的InnoDB必须在内存中运行。分割文件时，文件运行效率更高，因为它以较少的磁盘读写操作进入和退出内存，因为一个较大的文件需要更长的时间才能扫描数据。

它不交换，因为你的innodb_buffer_pool_size约束了MySQL加载到内存中的内存量。

解决您的问题的唯一方法是获取更多内存并为您的所有innodb表和索引分配足够的innodb_buffer_pool_size。