做网站的时候选数据库，MySQL是首选，但是服务器配置不高，如果不优化的话，服务器内存完全不够。于是找了一些国外大神的优化实例，希望能给大家一些启发。
MySQL设置项
下面一张表格是我从国外的一个博客里边摘抄下来的MySQL的一些默认配置项和最低设置参数。
| 设置项 | 默认 | 最低 |
| innodb_buffer_pool_size | 128M | 5M |
| innodb_log_buffer_size | 1M | 256K |
| query_cache_size | 1M | 0 |
| max_connections | 151 | 1 (推荐最低设置为10) |
| key_buffer_size | 8388608 | 8 |
| thread_cache_size | (自动配置) | 0 |
| host_cache_size | (自动配置) | 0 |
| innodb_ft_cache_size | 8000000 | 1600000 |
| innodb_ft_total_cache_size | 640000000 | 32000000 |
| thread_stack | 262144 | 131072 |
| sort_buffer_size | 262144 | 32K |
| read_buffer_size | 131072 | 8200 |
| read_rnd_buffer_size | 262144 | 8200 |
| max_heap_table_size | 16777216 | 16K |
| tmp_table_size | 16777216 | 1K |
| bulk_insert_buffer_size | 8388608 | 0 |
| join_buffer_size | 262144 | 128 |
| net_buffer_length | 16384 | 1K |
| innodb_sort_buffer_size | 1M | 64K |
| binlog_cache_size | 32K | 4K |
| binlog_stmt_cache_size | 32K | 4K |
MySQL优化设置
依据以上参数，MySQL的最小配置为：
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# /etc/my.cnf:
innodb_buffer_pool_size=5M
innodb_log_buffer_size=256K
query_cache_size=0
max_connections=10
key_buffer_size=8
thread_cache_size=0
host_cache_size=0
innodb_ft_cache_size=1600000
innodb_ft_total_cache_size=32000000
# per thread or per operation settings
thread_stack=131072
sort_buffer_size=32K
read_buffer_size=8200
read_rnd_buffer_size=8200
max_heap_table_size=16K
tmp_table_size=1K
bulk_insert_buffer_size=0
join_buffer_size=128
net_buffer_length=1K
innodb_sort_buffer_size=64K
#settings that relate to the binary log (if enabled)
binlog_cache_size=4K
binlog_stmt_cache_size=4K
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但是并不推荐使用最小配置，可以适当修改一下。
在另外一个博客上找到了一个比较适合于512M内存的配置：
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# Example MySQL config file for large systems.
#
# This is for a large system with memory = 512M where the system runs mainly
# MySQL.
#
# MySQL programs look for option files in a set of
# locations which depend on the deployment platform.
# You can copy this option file to one of those
# locations. For information about these locations, see:
# http://dev.mysql.com/doc/mysql/en/option-files.html
#
# In this file, you can use all long options that a program supports.
# If you want to know which options a program supports, run the program
# with the “–help” option.
# The following options will be passed to all MySQL clients
[client]
#password = your_password
port = 3306
socket = /var/lib/mysql/mysql.sock
# Here follows entries for some specific programs
# The MySQL server
[mysqld]
port = 3306
socket = /var/lib/mysql/mysql.sock
skip–external–locking
key_buffer_size = 256M
max_allowed_packet = 1M
table_open_cache = 256
sort_buffer_size = 1M
read_buffer_size = 1M
read_rnd_buffer_size = 4M
myisam_sort_buffer_size = 64M
thread_cache_size = 8
query_cache_size= 16M
# Try number of CPU’s*2 for thread_concurrency
thread_concurrency = 8
# Don’t listen on a TCP/IP port at all. This can be a security enhancement,
# if all processes that need to connect to mysqld run on the same host.
# All interaction with mysqld must be made via Unix sockets or named pipes.
# Note that using this option without enabling named pipes on Windows
# (via the “enable-named-pipe” option) will render mysqld useless!
#
#skip-networking
# Replication Master Server (default)
# binary logging is required for replication
log–bin=mysql–bin
# binary logging format – mixed recommended
binlog_format=mixed
# required unique id between 1 and 2^32 – 1
# defaults to 1 if master-host is not set
# but will not function as a master if omitted
server–id = 1
# Replication Slave (comment out master section to use this)
#
# To configure this host as a replication slave, you can choose between
# two methods :
#
# 1) Use the CHANGE MASTER TO command (fully described in our manual) –
# the syntax is:
#
# CHANGE MASTER TO MASTER_HOST=<host>, MASTER_PORT=<port>,
# MASTER_USER=<user>, MASTER_PASSWORD=<password> ;
#
# where you replace <host>, <user>, <password> by quoted strings and
# <port> by the master’s port number (3306 by default).
#
# Example:
#
# CHANGE MASTER TO MASTER_HOST=’125.564.12.1′, MASTER_PORT=3306,
# MASTER_USER=’joe’, MASTER_PASSWORD=’secret’;
#
# OR
#
# 2) Set the variables below. However, in case you choose this method, then
# start replication for the first time (even unsuccessfully, for example
# if you mistyped the password in master-password and the slave fails to
# connect), the slave will create a master.info file, and any later
# change in this file to the variables’ values below will be ignored and
# overridden by the content of the master.info file, unless you shutdown
# the slave server, delete master.info and restart the slaver server.
# For that reason, you may want to leave the lines below untouched
# (commented) and instead use CHANGE MASTER TO (see above)
#
# required unique id between 2 and 2^32 – 1
# (and different from the master)
# defaults to 2 if master-host is set
# but will not function as a slave if omitted
#server-id = 2
#
# The replication master for this slave – required
#master-host = <hostname>
#
# The username the slave will use for authentication when connecting
# to the master – required
#master-user = <username>
#
# The password the slave will authenticate with when connecting to
# the master – required
#master-password = <password>
#
# The port the master is listening on.
# optional – defaults to 3306
#master-port = <port>
#
# binary logging – not required for slaves, but recommended
#log-bin=mysql-bin
# Uncomment the following if you are using InnoDB tables
#innodb_data_home_dir = /var/lib/mysql
#innodb_data_file_path = ibdata1:10M:autoextend
#innodb_log_group_home_dir = /var/lib/mysql
# You can set .._buffer_pool_size up to 50 – 80 %
# of RAM but beware of setting memory usage too high
#innodb_buffer_pool_size = 256M
#innodb_additional_mem_pool_size = 20M
# Set .._log_file_size to 25 % of buffer pool size
#innodb_log_file_size = 64M
#innodb_log_buffer_size = 8M
#innodb_flush_log_at_trx_commit = 1
#innodb_lock_wait_timeout = 50
[mysqldump]
quick
max_allowed_packet = 16M
[mysql]
no–auto–rehash
# Remove the next comment character if you are not familiar with SQL
#safe-updates
[myisamchk]
key_buffer_size = 128M
sort_buffer_size = 128M
read_buffer = 2M
write_buffer = 2M
[mysqlhotcopy]
interactive–timeout
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链接：
1.Configuring MySQL to use minimal memory
2.Mysql sample configuration with 512M ram
