PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

Implementing Replication
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You need to edit your my.ini or my.cnf file on both the master and slave servers.
On the master, you need the following settings:
[mysqld]
log-bin
server-id=1
The first setting turns on binary logging (so you should already have this one; if not, add
it in now).The second setting gives your master server a unique ID. Each of the slaves
also needs an ID, so you need to add a similar line to the my.ini/my.cnf files on each of
the slaves. Make sure the numbers are unique! For example, your first slave could have
server-id=2; the next, server-id=3; and so on.
Setting Up the Master
On the master, you need to create a user for slaves to connect as.There is a special privilege
level for slaves called replication slave. Depending on how you plan to do the initial
data transfer, you may need to temporarily grant some additional privileges.
In most cases, you will use a database snapshot to transfer the data, and in this case,
only the special replication slave privilege is needed. If you decide to use the LOAD DATA
FROM MASTER command to transfer data (you learn about it in the next section), this user
will also need the RELOAD, SUPER, and SELECT privileges, but only for initial setup. As per
the principle of least privilege, discussed in Chapter 9, you should revoke these other
privileges after the system is up and running.
Create a user on the master.You can call it anything you like and give it any password
you like, but you should make a note of the username and password you choose. In our
example, we call this user rep_slave:
grant replication slave
on *.*
to ‘rep_slave’@’%’ identified by ‘password’;
Obviously, you should change the password to something else.
Performing the Initial Data Transfer
You can transfer the data from master to slave in several ways.The simplest is to set up
the slaves (described in the next section) and then run a LOAD DATA FROM MASTER statement.The
problem with this approach is that it will lock the tables on the master while
the data is being transferred, and this can take some time, so we do not recommend it.
(You can use this option only if you are using MyISAM tables.)
Generally, it is better to take a snapshot of the database at the current time.You can
do this by using the procedures described for taking backups elsewhere in this chapter.
You should first flush the tables with the following statement:
flush tables with read lock;