Thursday, September 15, 2011

Running Multiple MySQL versions

Sometimes we may require to run multiple versions of MySQL on the same Server. This can happen if you either need to test a new MySQL release or you need a new MySQL version and you don’t want to make any changes to the existing system.
The whole idea behind this is to compile the new MySQL server with different TCP/IP ports and Unix socket files so that each one is listening on different network interfaces. Compiling in different base directories for each installation also results in separate compiled-in data directory, log file, and PID file location for each server.
First download the source the tar file from
$> tar xfz mysql.tar.gz
$> cd mysql.XX
* Important **
“/etc/my.cnf ” is the default file that is used by a mysql server. When the new version is tested it will load the default configuration’s in /etc/my.cnf.
To resolve this I replaced every instance of ” cnf ” inside the source folder to ” conf ” by using this following command.
find ./ -type f | xargs perl -pi -w -e 's/cnf/conf/g;'
1) The default user generally is “mysql”. Add another user and group for example mysqlt for the new version of MySQL.
2) A typical ./configure command…
./configure --prefix=/usr/local/mysql --enable-local-infile
--with-tcp-port=4444 --with-mysqld-user=mysqlt
--with-base_dir=/usr/local/mysql --with-log=/usr/local/mysql/mysqld.log
-with-unix-socket-path=/tmp/mysqlt.sock --localstatedir=/var/lib/mysqlt
The new values you will use for your new MySQL server are:
Port number : 4444

mysql user : mysqlt

base_dir :  /usr/local/mysql

data directory : /var/lib/mysqlt

log file : /usr/local/mysql/mysqld.log
3) Compile and Install
make && make install
4)Create your new MySQL config file.
cp support-files/my-medium.conf /etc/my.conf
cd /usr/local/mysql
bin/mysql_install_db --user=mysqlt
( this will install all the needed databases )
bin/mysqld_safe --user=mysqlt &
/usr/local/mysql/bin/mysqladmin -u root -h hostname password 'new-password'

/usr/local/mysql/bin/mysqladmin -u root password 'new-password'
5) To start the service
cd /usr/local/mysql

./share/mysql/mysql.server start
6) To test
#telnet localhost 4444

and you should see this

Connected to localhost.

Escape character is '^]'.

+ 4.0.26-logIE^*THL
And you are done. You can copy mysql.server >> rc.d to start it when the server is rebooted.
With these steps, you can download and configure different mysql versions to use different values for port, datadirectory, mysql user, configuration file etc….
Warning: You should never have two servers that update data in the same databases.