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KILL
Syntax
KILL thread_id KILL CONNECTION thread_id KILL QUERY thread_id |
Each connection to mysqld
runs in a separate thread. You can see
which threads are running with the SHOW PROCESSLIST
command and kill
a thread with the KILL thread_id
command.
As of MySQL 5.0.0, KILL
allows the optional CONNECTION
or
QUERY
modifiers:
KILL CONNECTION
is the same as KILL
with no modifier:
It terminates the connection associated with the given thread_id
.
KILL QUERY
terminates the statement that the connection is executing,
but leaves the connection intact.
If you have the PROCESS
privilege, you can see all threads.
If you have the SUPER
privilege, you can kill all threads and
statements. Otherwise, you can only see and kill your own threads and
statements.
You can also use the mysqladmin processlist
and mysqladmin kill
commands to examine and kill threads.
Note: You currently cannot use KILL
with the Embedded MySQL
Server library, because the embedded server merely runs inside the threads
of the host application, it does not create connection threads of its own.
When you do a KILL
, a thread-specific kill flag
is set for
the thread.
In most cases it may take some time for the thread to die, as the kill flag is only checked at specific intervals.
SELECT
, ORDER BY
and GROUP BY
loops, the flag is
checked after reading a block of rows. If the kill flag is set, the
statement is aborted.
ALTER TABLE
the kill flag is checked before each block of
rows are read from the original table. If the kill flag was set the command
is aborted and the temporary table is deleted.
UPDATE
or DELETE
, the kill flag
is checked after each block read and after each updated or deleted
row. If the kill flag is set, the statement is aborted. Note that if you
are not using transactions, the changes will not be rolled back!
GET_LOCK()
will abort with NULL
.
INSERT DELAYED
thread will quickly flush all rows it has in
memory and die.
Locked
),
the table lock will be quickly aborted.
write
call, the
write is aborted with an disk full error message.
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