Описание тега mysqlnd
The MySQL native driver for PHP (mysqlnd) is a drop-in replacement for the MySQL Client Library (libmysql) for the PHP script language.
Because MySQL Native Driver is written as a PHP extension, it is tightly coupled to the workings of PHP.
This leads to gains in efficiency, especially when it comes to memory usage, as the driver uses the PHP memory management system. It also supports the PHP memory limit. Using MySQL Native Driver leads to comparable or better performance than using MySQL Client Library, it always ensures the most efficient use of memory. One example of the memory efficiency is the fact that when using the MySQL Client Library, each row is stored in memory twice, whereas with the MySQL Native Driver each row is only stored once in memory.