HOWTO: configure MySQL’s my.cnf file

UPDATE: I recently used this MySQL tuner script, I basically went with what it told me, but I’m using a higher query_cache_size than it recommends, basically because I don’t see anything online saying it will hurt things.  So I’m now using the following values on my server:

[mysqld]
user=mysql
bind-address=127.0.0.1
datadir=/var/lib/mysql
pid-file=/var/run/mysqld/mysqld.pid
socket=/var/run/mysql/mysql.sock
port=3306
tmpdir=/tmp
language=/usr/share/mysql/english
skip-external-locking
query_cache_limit=64M
query_cache_size=32M
query_cache_type=1
max_connections=15
max_user_connections=300
interactive_timeout=100
wait_timeout=100
connect_timeout=10
thread_stack=128K
thread_cache_size=128
myisam-recover=BACKUP
key_buffer=64M
join_buffer=1M
max_allowed_packet=32M
table_cache=512M
sort_buffer_size=1M
read_buffer_size=1M
read_rnd_buffer_size=768K
max_connect_errors=10
thread_concurrency=4
myisam_sort_buffer_size=32M
skip-locking
skip-bdb
expire_logs_days=10
max_binlog_size=100M
server-id=1
[mysql.server]
user=mysql
basedir=/usr
[safe_mysqld]
bind-address=127.0.0.1
err-log=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
open_files_limit=8192
SAFE_MYSQLD_OPTIONS=”–defaults-file=/etc/my.cnf –log-slow-queries=/var/log/slow-queries.log”
[mysql]
[isamchk]
key_buffer=64M
sort_buffer=64M
read_buffer=16M
write_buffer=16M
[myisamchk]
key_buffer=64M
sort_buffer=64M
read_buffer=16M
write_buffer=16M
[mysqlhotcopy]
interactive-timeout
max_heap_table_size = 64 M
tmp_table_size = 64 M
!includedir /etc/mysql/conf.d/

I’ve gone back and forth over the years configuring MySQL for optimal performance, and while I know I’m not there, I now have a new baseline to build from. From a post called Standard MYSQL my.cnf configuration, you can see all the base information, but also things like:

key_buffer=256M # 64M for 1GB, 128M for 2GB, 256 for 4GB

Which defines the value (256M) but then spells out ideal base values for you to start with if you have more RAM on your system. This is very helpful, I’m tried to go a step further by combining it with Debian’s default my.cnf that comes on 5.0 (lenny) for MySQL 5. As I’m always open for suggestions for improvements, please comment if you have a different view on these choices, thanks. Here it is:

[client]
socket=/var/run/mysqld/mysqld.sock
port=3306

[mysqld_safe]
socket=/var/run/mysqld/mysqld.sock
nice=0

[mysqld]
user=mysql
bind-address=127.0.0.1
datadir=/var/lib/mysql
pid-file=/var/run/mysqld/mysqld.pid
socket=/var/run/mysql/mysql.sock
port=3306
tmpdir=/tmp
language=/usr/share/mysql/english
skip-external-locking
query_cache_limit=1M
query_cache_size=32M
query_cache_type=1
max_connections=3000
max_user_connections=600
interactive_timeout=100
wait_timeout=100
connect_timeout=10
thread_stack=128K
thread_cache_size=128
myisam-recover=BACKUP
#key_buffer - 64M for 1GB, 128M for 2GB, 256 for 4GB
key_buffer=64M
#join_buffer_size - 1M for 1GB, 2M for 2GB, 4M for 4GB
join_buffer=1M
max_allowed_packet=32M
table_cache=1024
#sort_buffer_size - 1M for 1GB, 2M for 2GB, 4M for 4GB
sort_buffer_size=1M
#read_buffer_size - 1M for 1GB, 2M for 2GB, 4M for 4GB
read_buffer_size=1M
#read_rnd_buffer_size - 768K for 1GB, 1536K for 2GB, 3072K for 4GB
read_rnd_buffer_size=768K
max_connect_errors=10
thread_concurrency=4
#myisam_sort_buffer_size - 32M for 1GB, 64M for 2GB, 128 for 4GB
myisam_sort_buffer_size=32M
skip-locking
skip-bdb
expire_logs_days=10
max_binlog_size=100M
server-id=1

[mysql.server]
user=mysql
basedir=/usr

[safe_mysqld]
bind-address=127.0.0.1
err-log=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
open_files_limit=8192
SAFE_MYSQLD_OPTIONS=”–defaults-file=/etc/my.cnf –log-slow-queries=/var/log/slow-queries.log”

#[mysqldump]
#quick
#quote-names
#max_allowed_packet=16M

[mysql]
#no-auto-rehash # faster start of mysql but no tab completition

[isamchk]
#key_buffer - 64M for 1GB, 128M for 2GB, 256M for 4GB
key_buffer=64M
#sort_buffer - 64M for 1GB, 128M for 2GB, 256M for 4GB
sort_buffer=64M
#read_buffer - 16M for 1GB, 32M for 2GB, 64M for 4GB
read_buffer=16M
#write_buffer - 16M for 1GB, 32M for 2GB, 64M for 4GB
write_buffer=16M

[myisamchk]
#key_buffer - 64M for 1GB, 128M for 2GB, 256M for 4GB
key_buffer=64M
#sort_buffer - 64M for 1GB, 128M for 2GB, 256M for 4GB
sort_buffer=64M
#read_buffer - 16M for 1GB, 32M for 2GB, 64M for 4GB
read_buffer=16M
#write_buffer - 16M for 1GB, 32M for 2GB, 64M for 4GB
write_buffer=16M

[mysqlhotcopy]
interactive-timeout

!includedir /etc/mysql/conf.d/