PHP 8.2: MySQLi can no longer be compiled with
PHP historically supported two libraries to connect MySQL databases. For both
mysqli extension and
pdo_mysql extensions, these libraries provided underlying functionality for connectivity, querying, retrieval, and processing of retrieved data.
mysqlnd(MySQL Native Driver): Part of PHP project, and provides modern functionality such as returning native PHP data types (such as integers), follows same memory management as PHP core, and is generally more feature-rich.
libmysql: An external library provided by MySQL, and does not provide all the features of
mysqlnd, and has the disadvantages of an external library, such as not being able to properly trace or control memory usage, and potential library version mismatches. Further,
libmysqlis not available on Windows systems.
Since PHP 5.4,
mysqlnd is the default library, but it was possible to compile
pdo_mysql extensions with
libmysql with a compile-time configuration flag.
Since PHP 8.2 and later, compiling
mysqli extension with
libmysql is no longer supported.
Note that it is still possible to compile
libmysql, the support for
libmysqlmight be dropped in the
pdo_mysqlextension in the future.
Attempting to compile
mysqli with the
--with-mysqli=FILE option with a value results in a configuration error at compiler configuration step:
Linking mysqli against external library is no longer supported
It is unlikely that a significant number of PHP builds are affected by this change. Due to the feature-rich and more secure nature of
mysqlnd, it has long been used as the default MySQL library for PHP.
The most prominent features that
libmysql supported, but not provided by
- Support for automatic reconnecting.
mysqlndintentionally avoids this feature due to the unpredictable dangerous nature of this feature.
- Authentication via LDAP and SASL.
LDAP/SASL authentication support might be added to
mysqlnd to which a pull-request exists.
It is decided that
libmysql-style auto reconnect will not be added to
mysqlnd. Generally, a dropped database connection results in an exception being thrown, at which point the application and either attempt to re-connect, or gracefully shut down the application. Applications that previously depended on the automatic re-connect functionality now need to handle the potential exceptions and attempt to re-connect manually.
libmysql supported dropped, these functions no longer provide any auto-connect feature whatsoever.
mysqli.reconnect INI directive is removed in PHP 8.2 and later. This value was used in the ping functionality that no longer auto-connects.
Setting this directive does not cause any errors or warnings, and it has no effect either.
MySQLi extension provides a
mysqli_driver class to fetch the driver information (such as client version), as well as to configure certain characteristics of the driver, such as the reconnect feature only provided by the now-removed
mysqli_driver::$reconnect property is similar to the
mysqli.reconnect INI directive.
In PHP 8.2 and later, the
mysqli_driver::$reconnect property is removed. Attempting to retrieve it results in an undefined property warning. Trying to set it has no impact on the driver behavior, and results in a deprecation notice on dynamic properties.
Backwards Compatibility Impact
It is unlikely that the removal of
libmysql affects any common PHP builds.
In cPanel, the
mysqli extension compiled with
mysqlnd requires enabling the extensions named
nd_mysql from the cPanel control panel.
The most likely incompatibility occurred due to this change is the lack of auto-reconnect feature. The
libmysql auto-reconnect feature is somewhat unpredictable to begin with, and the ideal upgrade path would be to catch
mysqli exceptions, and re-establish the connection manually, or to gracefully quit the application.