MySQL 8.0 Reference Manual Including MySQL NDB Cluster 8.0
Components must be loaded into the server before they can be used. MySQL supports manual component loading at runtime and automatic loading during server startup.
While a component is loaded, information about it is available as described in Section 7.5.2, “Obtaining Component Information”.
The INSTALL COMPONENT and
UNINSTALL COMPONENT SQL statements
enable component loading and unloading. For example:
INSTALL COMPONENT 'file://component_validate_password'; UNINSTALL COMPONENT 'file://component_validate_password';
A loader service handles component loading and unloading, and also
registers loaded components in the
mysql.component system table.
The SQL statements for component manipulation affect server
operation and the mysql.component system table
as follows:
INSTALL COMPONENT loads
components into the server. The components become active
immediately. The loader service also registers loaded
components in the mysql.component system
table. For subsequent server restarts, the loader service
loads any components listed in
mysql.component during the startup
sequence. This occurs even if the server is started with the
--skip-grant-tables option. The
optional SET clause permits setting
component system-variable values when you install components.
UNINSTALL COMPONENT deactivates
components and unloads them from the server. The loader
service also unregisters the components from the
mysql.component system table so that the
server no longer loads them during its startup sequence for
subsequent restarts.
Compared to the corresponding INSTALL
PLUGIN statement for server plugins, the
INSTALL COMPONENT statement for
components offers the significant advantage that it is not
necessary to know any platform-specific file name suffix for
naming the component. This means that a given
INSTALL COMPONENT statement can be
executed uniformly across platforms.
A component when installed may also automatically install related loadable functions. If so, the component when uninstalled also automatically uninstalls those functions.