Commands that take an instance name fail if the name is not a valid instance name.

Commands that take an instance name fail if the instance does not exist.

Instance Manager maintains information about instance configuration in an internal (in-memory) cache. Initially, this information comes from the configuration file if it exists, but some commands change the configuration of an instance. Commands that modify the configuration file fail if the file does not exist or is not accessible to Instance Manager.

On Windows, the standard file is my.ini in the directory where Instance Manager is installed. On Unix, the standard configuration file is /etc/my.cnf. To specify a different configuration file, start Instance Manager with the --defaults-file option.

If a [mysqld] instance section exists in the configuration file, it must not contain any Instance Manager-specific options (see Section 4.6.10.2, “MySQL Instance Manager Configuration Files”). Therefore, you must not add any of these options if you change the configuration for an instance named mysqld.

START INSTANCE instance_name

This command attempts to start an offline instance. The command is asynchronous; it does not wait for the instance to start.

mysql> START INSTANCE mysqld4;
Query OK, 0 rows affected (0,00 sec)

STOP INSTANCE instance_name

This command attempts to stop an instance. The command is synchronous; it waits for the instance to stop.

mysql> STOP INSTANCE mysqld4;
Query OK, 0 rows affected (0,00 sec)

SHOW INSTANCES

Shows the names and status of all loaded instances.

mysql> SHOW INSTANCES;
+---------------+---------+
| instance_name | status  |
+---------------+---------+
| mysqld3       | offline |
| mysqld4       | online  |
| mysqld2       | offline |
+---------------+---------+

SHOW INSTANCE STATUS instance_name

Shows status and version information for an instance.

mysql> SHOW INSTANCE STATUS mysqld3;
+---------------+--------+---------+
| instance_name | status | version |
+---------------+--------+---------+
| mysqld3       | online | unknown |
+---------------+--------+---------+

SHOW INSTANCE OPTIONS instance_name

Shows the options used by an instance.

mysql> SHOW INSTANCE OPTIONS mysqld3;
+---------------+---------------------------------------------------+
| option_name   | value                                             |
+---------------+---------------------------------------------------+
| instance_name | mysqld3                                           |
| mysqld-path   | /home/cps/mysql/trees/mysql-4.1/sql/mysqld        |
| port          | 3309                                              |
| socket        | /tmp/mysql.sock3                                  |
| pid-file      | hostname.pid3                                     |
| datadir       | /home/cps/mysql_data/data_dir1/                   |
| language      | /home/cps/mysql/trees/mysql-4.1/sql/share/english |
+---------------+---------------------------------------------------+

SHOW instance_name LOG FILES

The command lists all log files used by the instance. The result set contains the path to the log file and the log file size. If no log file path is specified in the instance section of the configuration file (for example, log=/var/mysql.log), the Instance Manager tries to guess its placement. If Instance Manager is unable to guess the log file placement you should specify the log file location explicitly by using a log option in the appropriate instance section of the configuration file.

mysql> SHOW mysqld LOG FILES;
+-------------+------------------------------------+----------+
| Logfile     | Path                               | Filesize |
+-------------+------------------------------------+----------+
| ERROR LOG   | /home/cps/var/mysql/owlet.err      | 9186     |
| GENERAL LOG | /home/cps/var/mysql/owlet.log      | 471503   |
| SLOW LOG    | /home/cps/var/mysql/owlet-slow.log | 4463     |
+-------------+------------------------------------+----------+

Log options are described in Section 5.1.2, “Server Command Options”.

SHOW instance_name LOG {ERROR | SLOW | GENERAL} size[,offset_from_end]

This command retrieves a portion of the specified log file. Because most users are interested in the latest log messages, the size parameter defines the number of bytes to retrieve from the end of the log. To retrieve data from the middle of the log file, specify the optional offset_from_end parameter. The following example retrieves 21 bytes of data, starting 23 bytes before the end of the log file and ending 2 bytes before the end:

mysql> SHOW mysqld LOG GENERAL 21, 2;
+---------------------+
| Log                 |
+---------------------+
| using password: YES |
+---------------------+

SET instance_name.option_name[=option_value]

This command edits the specified instance's configuration section to change or add instance options. The option is added to the section is it is not already present. Otherwise, the new setting replaces the existing one.

mysql> SET mysqld2.port=3322;
Query OK, 0 rows affected (0.00 sec)

Changes made to the configuration file do not take effect until the MySQL server is restarted. In addition, these changes are not stored in the instance manager's local cache of instance settings until a FLUSH INSTANCES command is executed.

UNSET instance_name.option_name

This command removes an option from an instance's configuration section.

mysql> UNSET mysqld2.port;
Query OK, 0 rows affected (0.00 sec)

Changes made to the configuration file do not take effect until the MySQL server is restarted. In addition, these changes are not stored in the instance manager's local cache of instance settings until a FLUSH INSTANCES command is executed.

FLUSH INSTANCES

This command forces Instance Manager reread the configuration file and to refresh internal structures. This command should be performed after editing the configuration file. The command does not restart instances.

mysql> FLUSH INSTANCES;
Query OK, 0 rows affected (0.04 sec)

FLUSH INSTANCES is deprecated and will be removed in MySQL 5.2.