InnoDB Monitors, such as the Standard, Lock, and Tablespace monitors, provide detailed internal state information to the error log for diagnostics.
The InnoDB Monitor refers to particular kinds of monitors included in MariaDB and since the early versions of MySQL.
There are four types: the standard InnoDB monitor, the InnoDB Lock Monitor, InnoDB Tablespace Monitor and the InnoDB Table Monitor.
The standard InnoDB Monitor returns extensive InnoDB information, particularly lock, semaphore, I/O and buffer activity:
To enable the standard InnoDB Monitor, from , set the innodb_status_output system variable to 1. Before , running the following statement was the method used:
To disable the standard InnoDB monitor, either set the system variable to zero, or, before , drop the table
The CREATE TABLE and DROP TABLE method of enabling and disabling the InnoDB Monitor has been deprecated, and may be removed in a future version of MariaDB.
For a description of the output, see .
The InnoDB Lock Monitor displays additional lock information.
To enable the InnoDB Lock Monitor, the standard InnoDB monitor must be enabled. Then, from , set the system variable to 1. Before , running the following statement was the method used:
To disable the standard InnoDB monitor, either set the system variable to zero, or, before , drop the table
The CREATE TABLE and DROP TABLE method of enabling and disabling the InnoDB Lock Monitor has been deprecated, and may be removed in a future version of MariaDB.
The InnoDB Tablespace Monitor is deprecated, and may be removed in a future version of MariaDB.
Enabling the Tablespace Monitor outputs a list of file segments in the shared tablespace to the error log, and validates the tablespace allocation data structures.
To enable the Tablespace Monitor, run the following statement:
To disable it, drop the table:
The InnoDB Table Monitor is deprecated, and may be removed in a future version of MariaDB.
Enabling the Table Monitor outputs the contents of the InnoDB internal data dictionary to the error log every fifteen seconds.
To enable the Table Monitor, run the following statement:
To disable it, drop the table:
The statement can be used to obtain the standard InnoDB Monitor output when required, rather than sending it to the error log. It will also display the InnoDB Lock Monitor information if the system variable is set to 1.
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CREATE TABLE innodb_monitor (a INT) ENGINE=INNODB;DROP TABLE innodb_monitor;CREATE TABLE innodb_lock_monitor (a INT) ENGINE=INNODB;DROP TABLE innodb_lock_monitor;CREATE TABLE innodb_tablespace_monitor (a INT) ENGINE=INNODB;DROP TABLE innodb_tablespace_monitor;CREATE TABLE innodb_table_monitor (a INT) ENGINE=INNODB;DROP TABLE innodb_table_monitor;