Syntax:
STOP SLAVE [thread_types]

thread_types:
    [thread_type [, thread_type] ... ]

thread_type: IO_THREAD | SQL_THREAD

Stops the slave threads. STOP SLAVE requires the SUPER privilege.
Recommended best practice is to execute STOP SLAVE on the slave before
stopping the slave server (see
http://dev.mysql.com/doc/refman/5.1/en/server-shutdown.html, for more
information).

When using the row-based logging format: Prior to MySQL 5.1.35, you
should always execute STOP SLAVE on the slave before stopping the slave
server to help avoid the possibility of an inconsistent slave; in MySQL
5.1.35 and later, you should execute this statement on the slave prior
to shutting down the slave server if you are replicating any tables
that use a nontransactional storage engine (see the Note later in this
section). In MySQL 5.1.55 and later, you can also use STOP SLAVE
SQL_THREAD for this purpose.

Like START SLAVE, this statement may be used with the IO_THREAD and
SQL_THREAD options to name the thread or threads to be stopped.

*Note*: The transactional behavior of STOP SLAVE changed in MySQL
5.1.35. Previously, it took effect immediately. Beginning with MySQL
5.1.35, it waits until any current replication event group affecting
one or more nontransactional tables has finished executing (if there is
any such replication group), or until the user issues a KILL QUERY or
KILL CONNECTION statement. (Bug #319, Bug #38205)

URL: http://dev.mysql.com/doc/refman/5.1/en/stop-slave.html

