Mysqlnd

MySQL Native Driver for PHP, commonly known as mysqlnd, is a MySQL client library implemented as a PHP extension. It serves as a replacement for the libmysqlclient library used by PHP’s MySQL extensions to communicate with MySQL servers. Built into PHP, mysqlnd provides the client protocol handling, result fetching, and memory management directly within the PHP process, enabling the mysqli, PDO_MYSQL, and the legacy ext/mysql extensions to connect to MySQL without requiring an external client library.

Mysqlnd is designed to be tightly integrated with PHP and offers features that improve performance and deployment flexibility. It supports SSL/TLS encryption, protocol compression, and asynchronous querying through the mysqli extension. It also provides support for persistent connections, allowing reuse of connections across multiple requests to reduce connection overhead. Data fetched from the server is managed in PHP memory space, which can reduce data copying and simplify handling within PHP code.

Compared with using a separate libmysqlclient library, mysqlnd can simplify deployment because it is distributed as part of PHP. It enables a number of advanced PHP-specific capabilities, such as asynchronous query execution, multi-query support, and integrated memory management, while maintaining compatibility with the APIs exposed by mysqli and PDO_MYSQL. The driver is maintained as part of the PHP project and is typically the default MySQL client library for these extensions in modern PHP releases.

Limitations are mainly related to differences in feature support or behavior that may vary with server version or extension configuration. Overall, mysqlnd remains a central component for PHP applications that interact with MySQL, balancing performance, simplicity, and integration within the PHP ecosystem.