Plugin Overview

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;

+----------------------------+----------+--------------------+---------+---------+
| Name                       | Status   | Type               | Library | License |
+----------------------------+----------+--------------------+---------+---------+
...
| mysql_native_password      | ACTIVE   | AUTHENTICATION     | NULL    | GPL     |
| mysql_old_password         | ACTIVE   | AUTHENTICATION     | NULL    | GPL     |
| MRG_MyISAM                 | ACTIVE   | STORAGE ENGINE     | NULL    | GPL     |
...
+----------------------------+----------+--------------------+---------+---------+

If a plugin's Library column has the 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
...
*************************** 6. row ***************************
           PLUGIN_NAME: CSV
        PLUGIN_VERSION: 1.0
         PLUGIN_STATUS: ACTIVE
           PLUGIN_TYPE: STORAGE ENGINE
   PLUGIN_TYPE_VERSION: 100003.0
        PLUGIN_LIBRARY: NULL
PLUGIN_LIBRARY_VERSION: NULL
         PLUGIN_AUTHOR: Brian Aker, MySQL AB
    PLUGIN_DESCRIPTION: CSV storage engine
        PLUGIN_LICENSE: GPL
           LOAD_OPTION: FORCE
       PLUGIN_MATURITY: Stable
   PLUGIN_AUTH_VERSION: 1.0
*************************** 7. row ***************************
           PLUGIN_NAME: MEMORY
        PLUGIN_VERSION: 1.0
         PLUGIN_STATUS: ACTIVE
           PLUGIN_TYPE: STORAGE ENGINE
   PLUGIN_TYPE_VERSION: 100003.0
        PLUGIN_LIBRARY: NULL
PLUGIN_LIBRARY_VERSION: NULL
         PLUGIN_AUTHOR: MySQL AB
    PLUGIN_DESCRIPTION: Hash based, stored in memory, useful for temporary tables
        PLUGIN_LICENSE: GPL
           LOAD_OPTION: FORCE
       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:

This table does not contain information about:

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 mysqld option, but it requires a server restart.
  • A plugin can be installed with the mysql_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 mysqld 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 mysqld 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, where name is the plugin name and library is the plugin library. This format installs a single plugin from the given plugin library.
  • Plugins can also be specified in the format library, where library 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:

$ mysqld --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 mysqld 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, where name is the plugin name and library is the plugin library. This format installs a single plugin from the given plugin library.
  • Plugins can also be specified in the format library, where library 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:

$ mysqld --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
[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 mysql_plugin

A plugin can be installed with the mysql_plugin utility if the server is completely offline.

The syntax is:

mysql_plugin [options] <plugin> ENABLE|DISABLE

For example, to install the server_audit audit plugin, you could execute the following:

mysql_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 mysqld 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 mysqld 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:

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 ValueDescription
OFFDisables the plugin without removing it from the mysql.plugins table.
ONEnables the plugin. If the plugin cannot be initialized, then the server will still continue starting up, but the plugin will be disabled.
FORCEEnables the plugin. If the plugin cannot be initialized, then the server will fail to start with an error.
FORCE_PLUS_PERMANENTEnables 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 mysql_plugin can be uninstalled in one of two ways:

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.

See Also

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