Question
Answer and Explanation
The conflict between MySQLnd and nd_mysql usually arises due to a redundancy or incompatibility in the MySQL drivers used by PHP. Here's a detailed explanation:
MySQLnd (MySQL Native Driver):
- `MySQLnd` is a PHP extension designed as a native MySQL driver, aiming to provide improved performance and additional features by implementing its functions directly within PHP. It was introduced as an alternative to the older libmysqlclient, offering enhanced efficiency.
- It is bundled with PHP versions 5.3 and later by default, hence when enabled, this is used in the connection layer between PHP application and the MySQL server
nd_mysql (Deprecated Driver):
- `nd_mysql` (or sometimes referred to as just `mysql`) typically refers to the older, deprecated extension, usually implemented by using the older `libmysqlclient` library
- When this older `nd_mysql` or its older alias `mysql` extension, along with newer native drivers, are enabled, this often creates conflict with newer `mysqlnd`, the newer one often taking priority over it.
Why Conflict Occurs:
- Function Overlap: Both extensions provide functions to connect and interact with a MySQL database server. When two drivers are loaded that attempt to register same functions, this produces conflict that the webserver often logs during boot up.
- Deprecated Nature of `nd_mysql`: Because `nd_mysql` is often associated with `mysql`, which is officially deprecated, its inclusion in later PHP versions can cause instabilities if a native implementation like MySQLnd is already active. The usage is officially not advised any longer.
- Misconfiguration: Incorrect PHP configurations might accidentally try loading both extensions simultaneously by using conflicting directives such as ini flags (`extension=mysql` alongside `extension=mysqlnd`).
Troubleshooting the Conflict:
- Disable `nd_mysql`: You should verify which `mysql` driver you use in your web application (either native `mysqlnd`, older `mysql`) and then only keep the `extension=mysqlnd` enabled in your `php.ini` or webserver config if the applications needs to be connected via this.
- Check Your PHP Extensions: View loaded PHP modules/extensions via `php -m`, verify there is no `mysql` related duplicate (except when one of them is using `pdo_mysql`). Usually only the latest `mysqlnd` should be kept, while the old style one `mysql` should not be active, to avoid duplicate errors.
- Avoid Mixing Driver types in a single application: Modern PHP apps mostly use the PHP data objects to implement DB related connection `PDO_MYSQL` alongside with `mysqlnd`, which should eliminate the use of `nd_mysql`/`mysql` extension
By removing the deprecated `nd_mysql` or older `mysql` from PHP config and leaving `mysqlnd`, usually the conflict should be fixed