7.6.1 安装和卸载插件
Server plugins must be loaded into the server before they can be used. MySQL supports plugin loading at server startup and runtime. It is also possible to control the activation state of loaded plugins at startup, and to unload them at runtime.
While a plugin is loaded, information about it is available as described in Section 7.6.2, “Obtaining Server Plugin Information”.
Before a server plugin can be used, it must be installed using one of the following methods. In the descriptions, plugin_name
stands for a plugin name such as innodb
, csv
, or validate_password
.
A built-in plugin is known by the server automatically. By default, the server enables the plugin at startup. Some built-in plugins permit this to be changed with the --
option.plugin_name
[=activation_state
]
The mysql.plugin
system table serves as a registry of plugins (other than built-in plugins, which need not be registered). During the normal startup sequence, the server loads plugins registered in the table. By default, for a plugin loaded from the mysql.plugin
table, the server also enables the plugin. This can be changed with the --
option.plugin_name
[=activation_state
]
If the server is started with the --skip-grant-tables
option, plugins registered in the mysql.plugin
table are not loaded and are unavailable.
A plugin located in a plugin library file can be loaded at server startup with the --plugin-load
, --plugin-load-add
, or --early-plugin-load
option. Normally, for a plugin loaded at startup, the server also enables the plugin. This can be changed with the --
option.plugin_name
[=activation_state
]
The --plugin-load
and --plugin-load-add
options load plugins after built-in plugins and storage engines have initialized during the server startup sequence. The --early-plugin-load
option is used to load plugins that must be available prior to initialization of built-in plugins and storage engines.
The value of each plugin-loading option is a semicolon-separated list of plugin_library
and name
=
plugin_library
values. Each plugin_library
is the name of a library file that contains plugin code, and each name
is the name of a plugin to load. If a plugin library is named without any preceding plugin name, the server loads all plugins in the library. With a preceding plugin name, the server loads only the named plugin from the library. The server looks for plugin library files in the directory named by the plugin_dir
system variable.
Plugin-loading options do not register any plugin in the mysql.plugin
table. For subsequent restarts, the server loads the plugin again only if --plugin-load
, --plugin-load-add
, or --early-plugin-load
is given again. That is, the option produces a one-time plugin-installation operation that persists for a single server invocation.
--plugin-load
, --plugin-load-add
, and --early-plugin-load
enable plugins to be loaded even when --skip-grant-tables
is given (which causes the server to ignore the mysql.plugin
table). --plugin-load
, --plugin-load-add
, and --early-plugin-load
also enable plugins to be loaded at startup that cannot be loaded at runtime.
The --plugin-load-add
option complements the --plugin-load
option:
-
Each instance of
--plugin-load
resets the set of plugins to load at startup, whereas--plugin-load-add
adds a plugin or plugins to the set of plugins to be loaded without resetting the current set. Consequently, if multiple instances of--plugin-load
are specified, only the last one applies. With multiple instances of--plugin-load-add
, all of them apply. -
The argument format is the same as for
--plugin-load
, but multiple instances of--plugin-load-add
can be used to avoid specifying a large set of plugins as a single long unwieldy--plugin-load
argument. -
--plugin-load-add
can be given in the absence of--plugin-load
, but any instance of--plugin-load-add
that appears before--plugin-load
has no effect because--plugin-load
resets the set of plugins to load.
For example, these options:
--plugin-load=x --plugin-load-add=y
are equivalent to these options:
--plugin-load-add=x --plugin-load-add=y
and are also equivalent to this option:
--plugin-load="x;y"
But these options:
--plugin-load-add=y --plugin-load=x
are equivalent to this option:
--plugin-load=x
Plugins Installed with the 安装插件语句
A plugin located in a plugin library file can be loaded at runtime with the INSTALL PLUGIN
statement. The statement also registers the plugin in the mysql.plugin
table to cause the server to load it on subsequent restarts. For this reason, INSTALL PLUGIN
requires the INSERT
privilege for the mysql.plugin
table.
The plugin library file base name depends on your platform. Common suffixes are .so
for Unix and Unix-like systems, .dll
for Windows.
Example: The --plugin-load-add
option installs a plugin at server startup. To install a plugin named myplugin
from a plugin library file named somepluglib.so
, use these lines in a my.cnf
file:
[mysqld]
plugin-load-add=myplugin=somepluglib.so
In this case, the plugin is not registered in mysql.plugin
. Restarting the server without the --plugin-load-add
option causes the plugin not to be loaded at startup.
Alternatively, the INSTALL PLUGIN
statement causes the server to load the plugin code from the library file at runtime:
INSTALL PLUGIN myplugin SONAME 'somepluglib.so';
INSTALL PLUGIN
also causes “permanent” plugin registration: The plugin is listed in the mysql.plugin
table to ensure that the server loads it on subsequent restarts.
Many plugins can be loaded either at server startup or at runtime. However, if a plugin is designed such that it must be loaded and initialized during server startup, attempts to load it at runtime using INSTALL PLUGIN
produce an error:
mysql> INSTALL PLUGIN myplugin SONAME 'somepluglib.so';
ERROR 1721 (HY000): Plugin 'myplugin' is marked as not dynamically
installable. You have to stop the server to install it.
In this case, you must use --plugin-load
, --plugin-load-add
, or --early-plugin-load
.
If a plugin is named both using a --plugin-load
, --plugin-load-add
, or --early-plugin-load
option and (as a result of an earlier INSTALL PLUGIN
statement) in the mysql.plugin
table, the server starts but writes these messages to the error log:
[ERROR] Function 'plugin_name' already exists
[Warning] Couldn't load plugin named 'plugin_name'
with soname 'plugin_object_file'.
If the server knows about a plugin when it starts (for example, because the plugin is named using a --plugin-load-add
option or is registered in the mysql.plugin
table), the server loads and enables the plugin by default. It is possible to control activation state for such a plugin using a --
startup option, where plugin_name
[=activation_state
]plugin_name
is the name of the plugin to affect, such as innodb
, csv
, or validate_password
. As with other options, dashes and underscores are interchangeable in option names. Also, activation state values are not case-sensitive. For example, --my_plugin=ON
and --my-plugin=on
are equivalent.
-
--
plugin_name
=OFFTells the server to disable the plugin. Using this option, you can disable, for example, the deprecated
mysql_native_password
plugin at server startup. -
--
plugin_name
[=ON]Tells the server to enable the plugin. (Specifying the option as
--
without a value has the same effect.) If the plugin fails to initialize, the server runs with the plugin disabled.plugin_name
-
--
plugin_name
=FORCETells the server to enable the plugin, but if plugin initialization fails, the server does not start. In other words, this option forces the server to run with the plugin enabled or not at all.
-
--
plugin_name
=FORCE_PLUS_PERMANENTLike
FORCE
, but in addition prevents the plugin from being unloaded at runtime. If a user attempts to do so withUNINSTALL PLUGIN
, an error occurs.
Plugin activation states are visible in the LOAD_OPTION
column of the Information Schema PLUGINS
table.
Suppose that CSV
, BLACKHOLE
, and ARCHIVE
are built-in pluggable storage engines and that you want the server to load them at startup, subject to these conditions: The server is permitted to run if CSV
initialization fails, must require that BLACKHOLE
initialization succeeds, and should disable ARCHIVE
. To accomplish that, use these lines in an option file:
[mysqld]
csv=ON
blackhole=FORCE
archive=OFF
The --enable-
option format is a synonym for plugin_name
--
. The plugin_name
=ON--disable-
and plugin_name
--skip-
option formats are synonyms for plugin_name
--
.plugin_name
=OFF
If a plugin is disabled, either explicitly with OFF
or implicitly because it was enabled with ON
but fails to initialize, aspects of server operation requiring the plugin change. For example, if the plugin implements a storage engine, existing tables for the storage engine become inaccessible, and attempts to create new tables for the storage engine result in tables that use the default storage engine unless the NO_ENGINE_SUBSTITUTION
SQL mode is enabled to cause an error to occur instead.
Disabling a plugin may require adjustment to other options.
At runtime, the UNINSTALL PLUGIN
statement disables and uninstalls a plugin known to the server. The statement unloads the plugin and removes it from the mysql.plugin
system table, if it is registered there. For this reason, UNINSTALL PLUGIN
statement requires the DELETE
privilege for the mysql.plugin
table. With the plugin no longer registered in the table, the server does not load the plugin during subsequent restarts.
UNINSTALL PLUGIN
can unload a plugin regardless of whether it was loaded at runtime with INSTALL PLUGIN
or at startup with a plugin-loading option, subject to these conditions:
-
It cannot unload plugins that are built in to the server. These can be identified as those that have a library name of
NULL
in the output from the Information SchemaPLUGINS
table orSHOW PLUGINS
. -
It cannot unload plugins for which the server was started with
--
, which prevents plugin unloading at runtime. These can be identified from theplugin_name
=FORCE_PLUS_PERMANENTLOAD_OPTION
column of thePLUGINS
table.
To uninstall a plugin that currently is loaded at server startup with a plugin-loading option, use this procedure.
-
Remove from the
my.cnf
file any options and system variables related to the plugin. If any plugin system variables were persisted to themysqld-auto.cnf
file, remove them usingRESET PERSIST
for each one to remove it.var_name
-
Restart the server.
-
Plugins normally are installed using either a plugin-loading option at startup or with
INSTALL PLUGIN
at runtime, but not both. However, removing options for a plugin from themy.cnf
file may not be sufficient to uninstall it if at some pointINSTALL PLUGIN
has also been used. If the plugin still appears in the output fromPLUGINS
orSHOW PLUGINS
, useUNINSTALL PLUGIN
to remove it from themysql.plugin
table. Then restart the server again.
A plugin when installed may also automatically install related loadable functions. If so, the plugin when uninstalled also automatically uninstalls those functions.