Oracle 5.0 Reference Manual page 1307

InnoDB
• The Lock Monitor is like the standard Monitor but also provides extensive lock information.
InnoDB
To enable this Monitor for periodic output, create a table named innodb_lock_monitor.
• The Tablespace Monitor prints a list of file segments in the shared tablespace and validates
InnoDB
the tablespace allocation data structures. To enable this Monitor for periodic output, create a table
named innodb_tablespace_monitor.
• The Table Monitor prints the contents of the
InnoDB
Monitor for periodic output, create a table named innodb_table_monitor.
To enable an Monitor for periodic output, use a
InnoDB
table associated with the Monitor. For example, to enable the standard
table:
innodb_monitor
CREATE TABLE innodb_monitor (a INT) ENGINE=INNODB;
To stop the Monitor, drop the table:
DROP TABLE innodb_monitor;
The syntax is just a way to pass a command to the
CREATE TABLE
SQL parser: The only things that matter are the table name
table. The structure of the table is not relevant at all for the
InnoDB
the server, the Monitor does not restart automatically when you restart the server. You must drop the
Monitor table and issue a new
in a future release.)
When you enable
InnoDB
server standard error output (stderr). In this case, no output is sent to clients. When switched on,
Monitors print data about every 15 seconds. Server output usually is directed to the error log
InnoDB
(see Section 5.2.1, "The Error
start the server from a command prompt in a console window with the
want to direct the output to the window rather than to the error log.
sends diagnostic output to
InnoDB
buffers, to avoid potential buffer overflows. As a side effect, the output of
is written to a status file in the MySQL data directory every fifteen seconds. The name of
STATUS
the file is innodb_status.pid, where
for a normal shutdown. If abnormal shutdowns have occurred, instances of these status files may
be present and must be removed manually. Before removing them, you might want to examine
them to see whether they contain useful information about the cause of abnormal shutdowns. The
innodb_status.pid
is set.
Monitors should be enabled only when you actually want to see Monitor information because
InnoDB
output generation does result in some performance decrement. Also, if you enable monitor output by
creating the associated table, your error log may become quite large if you forget to remove the table
later.
For additional information about
• Mark Leith: InnoDB Table and Tablespace Monitors
• MySQL Performance Blog:
Each monitor begins with a header containing a timestamp and the monitor name. For example:
================================================
090407 12:06:19 INNODB TABLESPACE MONITOR OUTPUT
================================================
The header for the standard Monitor
because the latter produces the same output with the addition of extra lock information.
Performance Tuning and Troubleshooting
CREATE TABLE
Monitors for periodic output,
Log"). This data is useful in performance tuning. On Windows, you must
or to files rather than to
stderr
is the server process ID.
pid
file is created only if the configuration option
monitors, see the following resources:
InnoDB
SHOW INNODB STATUS walk through
(INNODB MONITOR
1287
internal data dictionary. To enable this
InnoDB
CREATE TABLE
InnoDB
innodb_monitor
InnoDB
statement to start the Monitor. (This syntax may change
writes their output to the
InnoDB
--console
stdout
InnoDB
innodb-status-file=1
OUTPUT) is also used for the Lock Monitor
statement to create the
Monitor, create the
InnoDB
engine through MySQL's
and that it be an
Monitor. If you shut down
mysqld
[404] option if you
or fixed-size memory
SHOW ENGINE INNODB
removes the file
[1236]