Optimize mysql

# Example MySQL config file for very large systems.
#
# This is for a large system with memory of 1G-2G where the system runs mainly
# MySQL.
#
# You can copy this file to
# /etc/my.cnf to set global options,
# mysql-data-dir/my.cnf to set server-specific options (in this
# installation this directory is /var/lib/mysql) or
# ~/.my.cnf to set user-specific options.
#
# 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-locking
max_connections=500
max_user_connections=70
key_buffer = 384M
max_allowed_packet = 16M
table_cache = 1024
sort_buffer_size = 2M
read_buffer_size = 2M
read_rnd_buffer_size = 8M
myisam_sort_buffer_size = 64M
thread_cache_size = 128
query_cache_limit=8M
query_cache_size = 256M
query_cache_type = 1
wait_timeout=30
connect_timeout=30
interactive_timeout=30
record_buffer=1M
join_buffer_size=1M
myisam_sort_buffer_size=64M
log-error=/var/log/mysqld.log

#query_cache_limit=2M
local-infile=0
#bind-address = 127.0.0.1
max_connect_errors=60
# 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

# 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

# Point the following paths to different dedicated disks
#tmpdir = /tmp/
#log-update = /path-to-dedicated-directory/hostname

# Uncomment the following if you are using BDB tables
#bdb_cache_size = 384M
#bdb_max_lock = 100000

# Uncomment the following if you are using InnoDB tables
#innodb_data_home_dir = /var/lib/mysql/
#innodb_data_file_path = ibdata1:2000M;ibdata2:10M:autoextend
#innodb_log_group_home_dir = /var/lib/mysql/
#innodb_log_arch_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 = 384M
#innodb_additional_mem_pool_size = 20M
# Set .._log_file_size to 25 % of buffer pool size
#innodb_log_file_size = 100M
#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

[isamchk]
key_buffer = 256M
sort_buffer_size = 256M
read_buffer = 16M
write_buffer = 16M

[myisamchk]
key_buffer = 256M
sort_buffer_size = 256M
read_buffer = 16M
write_buffer = 16M

[mysqlhotcopy]
interactive-timeout

Installing Memcache on CentOS

1

• Check to make sure that you are running a recent version of CentOS by entering "cat /etc/redhat-release." As of June 2011, the most recent version of CentOS is version 5.6.
• 2
  Download and setup your system and Memcache to be installed on your server by entering the following commands:

  "cd /user/local/src"

  "curl -O http://memcached.googlecode.com/files/memcached-1.4.5.tar.gz"

  "tar xzvf memcached-1.4.5.tar.gz"

  "cd memcached-1.4.5"

  "LDFLAGS='-W1, --rpath /usr/local/lib' ./configure --prefix=/usr/local"

  These commands move the src directory on your system, download Memcache and set the flags that are required to make Memcache work properly on your system.
• 3
  Run a simple make install to complete the Memcache installation; the code for this is "make && make install." Please note that you will need root privileges to run this command successfully; this is done in CentOS using the "su" command and entering your root password. Be sure that when the process is completed you "su" back your regular user.
• 4
  Verify that Memcache is installed properly on your system using the following command: "ps auz | grep memcached." If there are no errors printed in your terminal, then everything is fine with your installation. You can stop Memcache with "pkill memcached."

eHow

mysqldump: Error 2013: Lost connection to MySQL server during query when dumping table

Try increasing the value of the max_allowed_packet system variable. Default size is 1MB but it sounds like you are exceeding this. 

To set this add 

max_allowed_packet=64M

(replacing the 64M with whatever value you require) to your config file and restart the server or log into mysql client and issue 

SET GLOBAL max_allowed_packet=67108864

Note: Value in the config file can be followed by M, K to specifiy mb or kb but when using a SET command the value must be given as bytes or as an expression (eg you could specify a 64mb max_allowed_packet using SET GLOBAL max_allowed_packet=64*1024*1024). 


Hopefully this should resolve your problem. 


Sorry forgot to mention that mysqldump also has a max_allowed_packet option and you should try setting this in addition to the above when you run mysqldump. Just start mysqldump with a --max_allowed_packet= option. 

Source: forums.mysql.com