Plugin Overview
Contents
- Querying Plugin Information
- Installing a Plugin
- Uninstalling Plugins
- See Also
Plugins are server components that enhance MariaDB in some way. These can be anything from new storage engines, plugins for enhancing full-text parsing, or even small enhancements, such as a plugin to get a timestamp as an integer.
Querying Plugin Information
There are a number of ways to see which plugins are currently active.
A server almost always has a large number of active plugins, because the server contains a large number of built-in plugins, which are active by default and cannot be uninstalled.
Querying Plugin Information with SHOW PLUGINS
The SHOW PLUGINS statement can be used to query information about all active plugins.
For example:
SHOW PLUGINS\G; ********************** 1. row ********************** Name: binlog Status: ACTIVE Type: STORAGE ENGINE Library: NULL License: GPL ********************** 2. row ********************** Name: mysql_native_password Status: ACTIVE Type: AUTHENTICATION Library: NULL License: GPL ********************** 3. row ********************** Name: mysql_old_password Status: ACTIVE Type: AUTHENTICATION Library: NULL License: GPL ...
If a plugin's Library
column has a NULL
value, then the plugin is built-in, and it cannot be uninstalled.
Querying Plugin Information with information_schema.PLUGINS
The information_schema.PLUGINS table can be queried to get more detailed information about plugins.
For example:
SELECT * FROM information_schema.PLUGINS\G ... *************************** 65. row *************************** PLUGIN_NAME: user_variables PLUGIN_VERSION: 1.0 PLUGIN_STATUS: ACTIVE PLUGIN_TYPE: INFORMATION SCHEMA PLUGIN_TYPE_VERSION: 110600.0 PLUGIN_LIBRARY: NULL PLUGIN_LIBRARY_VERSION: NULL PLUGIN_AUTHOR: Sergey Vojtovich PLUGIN_DESCRIPTION: User-defined variables PLUGIN_LICENSE: GPL LOAD_OPTION: ON PLUGIN_MATURITY: Stable PLUGIN_AUTH_VERSION: 1.0 *************************** 66. row *************************** PLUGIN_NAME: wsrep_provider PLUGIN_VERSION: 1.0 PLUGIN_STATUS: ACTIVE PLUGIN_TYPE: REPLICATION PLUGIN_TYPE_VERSION: 2.0 PLUGIN_LIBRARY: NULL PLUGIN_LIBRARY_VERSION: NULL PLUGIN_AUTHOR: Codership Oy PLUGIN_DESCRIPTION: Wsrep provider plugin PLUGIN_LICENSE: GPL LOAD_OPTION: ON PLUGIN_MATURITY: Alpha PLUGIN_AUTH_VERSION: 1.0 *************************** 67. row *************************** PLUGIN_NAME: THREAD_POOL_GROUPS PLUGIN_VERSION: 1.0 PLUGIN_STATUS: ACTIVE PLUGIN_TYPE: INFORMATION SCHEMA PLUGIN_TYPE_VERSION: 110600.0 PLUGIN_LIBRARY: NULL PLUGIN_LIBRARY_VERSION: NULL PLUGIN_AUTHOR: Vladislav Vaintroub PLUGIN_DESCRIPTION: Provides information about threadpool groups. PLUGIN_LICENSE: GPL LOAD_OPTION: ON PLUGIN_MATURITY: Stable PLUGIN_AUTH_VERSION: 1.0 ...
If a plugin's PLUGIN_LIBRARY
column has the NULL
value, then the plugin is built-in, and it cannot be uninstalled.
Querying Plugin Information with mysql.plugin
The mysql.plugin table can be queried to get information about installed plugins.
This table only contains information about plugins that have been installed via the following methods:
- The INSTALL SONAME statement.
- The INSTALL PLUGIN statement.
- The mariadb-plugin utility.
This table does not contain information about:
- Built-in plugins.
- Plugins loaded with the --plugin-load-add option.
- Plugins loaded with the --plugin-load option.
This table only contains enough information to reload the plugin when the server is restarted, which means it only contains the plugin name and the plugin library.
For example:
SELECT * FROM mysql.plugin; +------+------------+ | name | dl | +------+------------+ | PBXT | libpbxt.so | +------+------------+
Installing a Plugin
There are three primary ways to install a plugin:
- A plugin can be installed dynamically with an SQL statement.
- A plugin can be installed with a mariadbd option, but it requires a server restart.
- A plugin can be installed with the mariadb-plugin utility, while the server is completely offline.
When you are installing a plugin, you also have to ensure that:
- The server's plugin directory is properly configured, and the plugin's library is in the plugin directory.
- The server's minimum plugin maturity is properly configured, and the plugin is mature enough to be installed.
Installing a Plugin Dynamically
A plugin can be installed dynamically by executing either the INSTALL SONAME or the INSTALL PLUGIN statement.
If a plugin is installed with one of these statements, then a record will be added to the mysql.plugins table for the plugin. This means that the plugin will automatically be loaded every time the server restarts, unless specifically uninstalled or deactivated.
Installing a Plugin with INSTALL SONAME
You can install a plugin dynamically by executing the INSTALL SONAME statement. INSTALL SONAME installs all plugins from the given plugin library. This could be required for some plugin libraries.
For example, to install all plugins in the server_audit
plugin library (which is currently only the server_audit audit plugin), you could execute the following:
INSTALL SONAME 'server_audit';
Installing a Plugin with INSTALL PLUGIN
You can install a plugin dynamically by executing the INSTALL PLUGIN statement. INSTALL PLUGIN installs a single plugin from the given plugin library.
For example, to install the server_audit audit plugin from the server_audit
plugin library, you could execute the following:
INSTALL PLUGIN server_audit SONAME 'server_audit';
Installing a Plugin with Plugin Load Options
A plugin can be installed with a mariadbd option by providing either the --plugin-load-add or the --plugin-load option.
If a plugin is installed with one of these options, then a record will not be added to the mysql.plugins table for the plugin. This means that if the server is restarted without the same option set, then the plugin will not automatically be loaded.
Installing a Plugin with --plugin-load-add
You can install a plugin with the --plugin-load-add option by specifying the option as a command-line argument to mariadbd or by specifying the option in a relevant server option group in an option file.
The --plugin-load-add option uses the following format:
- Plugins can be specified in the format
name=library
, wherename
is the plugin name andlibrary
is the plugin library. This format installs a single plugin from the given plugin library. - Plugins can also be specified in the format
library
, wherelibrary
is the plugin library. This format installs all plugins from the given plugin library. - Multiple plugins can be specified by separating them with semicolons.
For example, to install all plugins in the server_audit
plugin library (which is currently only the server_audit
audit plugin) and also the ed25519
authentication plugin from the auth_ed25519
plugin library, you could set the option to the following values on the command-line:
$ mariadbd --user=mysql --plugin-load-add='server_audit' --plugin-load-add='ed25519=auth_ed25519'
You could also set the option to the same values in an option file:
[mariadb] ... plugin_load_add = server_audit plugin_load_add = ed25519=auth_ed25519
Special care must be taken when specifying both the --plugin-load option and the --plugin-load-add option together. The --plugin-load option resets the plugin load list, and this can cause unexpected problems if you are not aware. The --plugin-load-add option does not reset the plugin load list, so it is much safer to use. See Specifying Multiple Plugin Load Options for more information.
Installing a Plugin with --plugin-load
You can install a plugin with the --plugin-load option by specifying the option as a command-line argument to mariadbd or by specifying the option in a relevant server option group in an option file.
The --plugin-load option uses the following format:
- Plugins can be specified in the format
name=library
, wherename
is the plugin name andlibrary
is the plugin library. This format installs a single plugin from the given plugin library. - Plugins can also be specified in the format
library
, wherelibrary
is the plugin library. This format installs all plugins from the given plugin library. - Multiple plugins can be specified by separating them with semicolons.
For example, to install all plugins in the server_audit
plugin library (which is currently only the server_audit
audit plugin) and also the ed25519
authentication plugin from the auth_ed25519
plugin library, you could set the option to the following values on the command-line:
$ mariadbd --user=mysql --plugin-load='server_audit;ed25519=auth_ed25519'
You could also set the option to the same values in an option file:
[mariadb] ... plugin_load = server_audit;ed25519=auth_ed25519
Special care must be taken when specifying the --plugin-load
option multiple times, or when specifying both the --plugin-load
option and the --plugin-load-add
option together. The --plugin-load
option resets the plugin load list, and this can cause unexpected problems if you are not aware. The --plugin-load-add
option does not reset the plugin load list, so it is much safer to use. See Specifying Multiple Plugin Load Options for more information.
Specifying Multiple Plugin Load Options
Special care must be taken when specifying the --plugin-load
option multiple times, or when specifying both the --plugin-load
option and the --plugin-load-add
option. The --plugin-load
option resets the plugin load list, and this can cause unexpected problems if you are not aware. The --plugin-load-add
option does not reset the plugin load list, so it is much safer to use.
This can have the following consequences:
- If the
--plugin-load
option is specified multiple times, then only the last instance will have any effect. For example, in the following case, the first instance of the option is reset:
[mariadb] ... plugin_load = server_audit plugin_load = ed25519=auth_ed25519
- If the
--plugin-load
option is specified after the--plugin-load-add
option, then it will also reset the changes made by that option. For example, in the following case, the--plugin-load-add
option does not do anything, because the subsequent--plugin-load
option resets the plugin load list:
[mariadb] ... plugin_load_add = server_audit plugin_load = ed25519=auth_ed25519
- In contrast, if the
--plugin-load
option is specified before the--plugin-load-add
option, then it will work fine, because the--plugin-load-add
option does not reset the plugin load list. For example, in the following case, both plugins are properly loaded:
[mariadb] ... plugin_load = server_audit plugin_load_add = ed25519=auth_ed25519
Installing a Plugin with mariadb-plugin
A plugin can be installed with the mariadb-plugin utility if the server is completely offline.
The syntax is:
mariadb-plugin [options] <plugin> ENABLE|DISABLE
For example, to install the server_audit audit plugin, you could execute the following:
mariadb-plugin server_audit ENABLE
If a plugin is installed with this utility, then a record will be added to the mysql.plugins table for the plugin. This means that the plugin will automatically be loaded every time the server restarts, unless specifically uninstalled or deactivated.
Configuring the Plugin Directory
When a plugin is being installed, the server looks for the plugin's library in the server's plugin directory. This directory is configured by the plugin_dir
system variable. This can be specified as a command-line argument to mariadbd
or it can be specified in a relevant server option group in an option file. For example:
[mariadb] ... plugin_dir = /usr/lib64/mysql/plugin
Configuring the Minimum Plugin Maturity
When a plugin is being installed, the server compares the plugin's maturity level against the server's minimum allowed plugin maturity. This can help prevent users from using unstable plugins on production servers. This minimum plugin maturity is configured by the plugin_maturity
system variable. This can be specified as a command-line argument to mariadbd
or it can be specified in a relevant server option group in an option file. For example:
[mariadb] ... plugin_maturity = stable
Configuring Plugin Activation at Server Startup
A plugin will be loaded by default when the server starts if:
- The plugin was installed with the INSTALL SONAME statement.
- The plugin was installed with the INSTALL PLUGIN statement.
- The plugin was installed with the mariadb-plugin utility.
- The server is configured to load the plugin with the --plugin-load-add option.
- The server is configured to load the plugin with the --plugin-load option.
This behavior can be changed with special options that take the form --plugin-name
. For example, for the server_audit
audit plugin, the special option is called --server-audit.
The possible values for these special options are:
Option Value | Description |
---|---|
OFF | Disables the plugin without removing it from the mysql.plugins table. |
ON | Enables the plugin. If the plugin cannot be initialized, then the server will still continue starting up, but the plugin will be disabled. |
FORCE | Enables the plugin. If the plugin cannot be initialized, then the server will fail to start with an error. |
FORCE_PLUS_PERMANENT | Enables the plugin. If the plugin cannot be initialized, then the server will fail to start with an error. In addition, the plugin cannot be uninstalled with UNINSTALL SONAME or UNINSTALL PLUGIN while the server is running. |
A plugin's status can be found by looking at the PLUGIN_STATUS
column of the information_schema.PLUGINS table.
Uninstalling Plugins
Plugins that are found in the mysql.plugin table, that is those that were installed with INSTALL SONAME, INSTALL PLUGIN or mariadb-plugin can be uninstalled in one of two ways:
- The UNINSTALL SONAME or the UNINSTALL PLUGIN statement while the server is running
- With mariadb-plugin while the server is offline.
Plugins that were enabled as a --plugin-load
option do not need to be uninstalled. If --plugin-load
is omitted the next time the server starts, or the plugin is not listed as one of the --plugin-load
entries, the plugin will not be loaded.
UNINSTALL PLUGIN uninstalls a single installed plugin, while UNINSTALL SONAME uninstalls all plugins belonging to a given library.