之前安装时没注意MySQL的优化,先想对MySQL做一下优化.首先看一下没有优化之前各个参数:MySQL预编译参数: ./configure --prefix=/usr/local/mysql --with-ssl --with-readline --with-big-tables --enable-assembler top 32553 mysql 20 0 125m 17m 40 S 0.

之前安装时没注意MySQL的优化,先想对MySQL做一下优化.首先看一下没有优化之前各个参数: MySQL预编译参数:

 ./configure --prefix=/usr/local/mysql --with-ssl --with-readline --with-big-tables --enable-assembler

top

32553 mysql 20 0 125m 17m 40 S 0.0 1.7 5:13.01 mysqld

使用mysqlreport获取MySQL运行参数:

MySQL 5.0.40-log uptime 15 22:1:21 Sat Feb 4 10:04:23 2012
__ Key _________________________________________________________________
Buffer used 62.00k of 16.00M %Used: 0.38
 Current 1.90M %Usage: 11.
Write hit 22.29%
Read hit 99.83%
__ Questions ___________________________________________________________
Total 85.58k 0.1/s
 DMS 77.61k 0.1/s %Total: 90.69
 Com_ 5.37k 0.0/s 6.28
 COM_QUIT 2.52k 0.0/s 2.95
 +Unknown 78 0.0/s 0.09
Slow 10 s 0 0/s 0.00 %DMS: 0.00 Log: OFF
DMS 77.61k 0.1/s 90.69
 SELECT 72.77k 0.1/s 85.03 93.76
 UPDATE 2.68k 0.0/s 3.13 3.45
 INSERT 1.09k 0.0/s 1.27 1.41
 DELETE 1.07k 0.0/s 1.25 1.38
 REPLACE 0 0/s 0.00 0.00
Com_ 5.37k 0.0/s 6.28
 set_option 2.60k 0.0/s 3.04
 change_db 2.52k 0.0/s 2.94
 show_fields 77 0.0/s 0.09
__ SELECT and Sort _____________________________________________________
Scan 5.17k 0.0/s %SELECT: 7.10
Range 2.75k 0.0/s 3.77
Full join 0 0/s 0.00
Range check 0 0/s 0.00
Full rng join 0 0/s 0.00
Sort scan 5.97k 0.0/s
Sort range 4.30k 0.0/s
Sort mrg pass 0 0/s
__ Table Locks _________________________________________________________
Waited 24 0.0/s %Total: 0.03
Immediate 91.00k 0.1/s
__ Tables ______________________________________________________________
Open 36 of  %Cache: 56.25
Opened 42 0.0/s
__ Connections _________________________________________________________
Max used 5 of 100 %Max: 5.00
Total 2.52k 0.0/s
__ Created Temp ________________________________________________________
Disk table 4.15k 0.0/s
Table 7.11k 0.0/s Size: 32.0M
File 5 0.0/s
__ Threads _____________________________________________________________
Running 1 of 1
Cached 0 of 0 %Hit: 0.04
Created 2.52k 0.0/s
Slow 0 0/s
__ Aborted _____________________________________________________________
Clients 0 0/s
Connects 0 0/s
__ Bytes _______________________________________________________________
Sent 226.71M 1.8/s
Received 12.59M 9.2/s
__ InnoDB Buffer Pool __________________________________________________
Usage 304.00k of 8.00M %Used: 3.71
Read hit 84.42%
Pages
 Free 493 %Total: 96.29
 Data 19 3.71 %Drty: 0.00
 Misc 0 0.00
 Latched 0 0.00
Reads 77 0.0/s
 From file 12 0.0/s 15.58
 Ahead Rnd 1 0.0/s
 Ahead Sql 0 0/s
Writes 0 0/s
Flushes 0 0/s
Wait Free 0 0/s
__ InnoDB Lock _________________________________________________________
Waits 0 0/s
Current 0
Time acquiring
 Total 0 ms
 Average 0 ms
 Max 0 ms
__ InnoDB Data, Pages, Rows ____________________________________________
Data
 Reads 25 0.0/s
 Writes 3 0.0/s
 fsync 3 0.0/s
 Pending
 Reads 0
 Writes 0
 fsync 0
Pages
 Created 0 0/s
 Read 19 0.0/s
 Written 0 0/s
Rows
 Deleted 0 0/s
 Inserted 0 0/s
 Read 0 0/s
 Updated 0 0/s

首先在预编译参数上进行优化

./configure --prefix=/usr/local/mysql \
--without-debug \ # 取消调试模式提高性能
--with-extra-charsets=utf8,gbk \ # 仅仅指定需要的默认字符集提高性能
--enable-assembler \ # 使用汇编模式提高性能
--with-mysqld-ldflags=-all-static \ # 以静态方式编译提高性能
--with-client-ldflags=-all-static \
--with-unix-socket-path=/tmp/mysql.sock \ # 使用unix socket提高性能
--with-ssl

安装完成后进一步优化my.cnf: 因为MySQL 只会 Cache 索引(*.MYI)，因此您只要将数据库中所有的 MYI 档案加总起来就是key buffer 的值,计算MYI档案的总大小:

du -hc `find /usr/local/mysql/var/ -name *.MYI`
4.0K /usr/local/mysql/var/myblog/wp_term_taxonomy.MYI
8.0K /usr/local/mysql/var/myblog/wp_posts.MYI
8.0K /usr/local/mysql/var/myblog/wp_usermeta.MYI
8.0K /usr/local/mysql/var/myblog/wp_commentmeta.MYI
16K /usr/local/mysql/var/myblog/wp_options.MYI
12K /usr/local/mysql/var/myblog/wp_postmeta.MYI
8.0K /usr/local/mysql/var/myblog/wp_comments.MYI
4.0K /usr/local/mysql/var/myblog/wp_links.MYI
4.0K /usr/local/mysql/var/myblog/wp_term_relationships.MYI
4.0K /usr/local/mysql/var/myblog/wp_users.MYI
8.0K /usr/local/mysql/var/myblog/wp_terms.MYI
16K /usr/local/mysql/var/mysql/help_relation.MYI
4.0K /usr/local/mysql/var/mysql/time_zone_name.MYI
16K /usr/local/mysql/var/mysql/help_keyword.MYI
4.0K /usr/local/mysql/var/mysql/func.MYI
4.0K /usr/local/mysql/var/mysql/time_zone.MYI
20K /usr/local/mysql/var/mysql/help_topic.MYI
4.0K /usr/local/mysql/var/mysql/columns_priv.MYI
4.0K /usr/local/mysql/var/mysql/procs_priv.MYI
4.0K /usr/local/mysql/var/mysql/time_zone_leap_second.MYI
4.0K /usr/local/mysql/var/mysql/user.MYI
4.0K /usr/local/mysql/var/mysql/tables_priv.MYI
4.0K /usr/local/mysql/var/mysql/host.MYI
4.0K /usr/local/mysql/var/mysql/time_zone_transition_type.MYI
4.0K /usr/local/mysql/var/mysql/proc.MYI
4.0K /usr/local/mysql/var/mysql/help_category.MYI
4.0K /usr/local/mysql/var/mysql/db.MYI
4.0K /usr/local/mysql/var/mysql/time_zone_transition.MYI
192K total

修改my.cnf参数大小:

vi /etc/my.cnf
# 降低key_buffer的值
key_buffer = 4M

重启MySQL执行top命令:

18125 mysql 20 0 109m 11m 2152 S 0.0 1.1 0:00.08 mysqld

看到MySQL的内存利用率降低到1.1,这时候还不适宜执行mysqlreport查看等待启动一天后查看.由于现在访问量较低,所以参数适量调低,需要实时监控MySQL运行状况适当运行参数.

原文地址：MySQL优化笔记, 感谢原作者分享。