The behaviour of these functions is affected by settings in php.ini.
| Name | Default | Changeable | Changelog |
|---|---|---|---|
| mysqlnd.collect_statistics | "1" | PHP_INI_SYSTEM | Available since PHP 5.3.0. |
| mysqlnd.collect_memory_statistics | "0" | PHP_INI_SYSTEM | Available since PHP 5.3.0. |
| mysqlnd.debug | "0" | PHP_INI_SYSTEM | Available since PHP 5.3.0. |
| mysqlnd.net_read_timeout | "31536000" | PHP_INI_SYSTEM | Available since PHP 5.3.0. |
| mysqlnd.net_cmd_buffer_size | 5.3.0 - "2048", 5.3.1 - "4096" | PHP_INI_SYSTEM | Available since PHP 5.3.0. |
| mysqlnd.net_read_buffer_size | "32768" | PHP_INI_SYSTEM | Available since PHP 5.3.0. |
Here's a short explanation of the configuration directives.
Enables the collection of various client statistics which can be accessed through mysqli_get_client_stats(), mysqli_get_connection_stats(), mysqli_get_cache_stats() and are shown in mysqlnd section of the output of the phpinfo() function as well.
This configuration setting enables all MySQL Native Driver statistics except those relating to memory management.
Enable the collection of various memory statistics which can be accessed through mysqli_get_client_stats(), mysqli_get_connection_stats(), mysqli_get_cache_stats() and are shown in mysqlnd section of the output of the phpinfo() function as well.
This configuration setting enables the memory management statistics within the overall set of MySQL Native Driver statistics.
Records everything from all extensions using mysqlnd. Only available with a debug build of PHP.
mysqlnd and the MySQL Client Library, libmysql use different networking APIs. mysqlnd uses PHP streams, whereas libmysql uses its own wrapper around the operating level network calls. PHP, by default, sets a read timeout of 60s for streams. This is set via php.ini, default_socket_timeout. This default applies to all streams that set no other timeout value. mysqlnd does not set any other value and therefore connections of long running queries can be disconnected after default_socket_timeout seconds resulting in an error message "2006 - MySQL Server has gone away". The MySQL Client Library sets a default timeout of 365 * 24 * 3600 seconds (1 year) and waits for other timeouts to occur, such as TCP/IP timeouts. mysqlnd now uses the same very long timeout. The value is configurable through a new php.ini setting: mysqlnd.net_read_timeout. mysqlnd.net_read_timeout gets used by any extension (ext/mysql, ext/mysqli, PDO_MySQL) that uses mysqlnd. mysqlnd tells PHP Streams to use mysqlnd.net_read_timeout. Please note that there may be subtle differences between MYSQL_OPT_READ_TIMEOUT from the MySQL Client Library and PHP Streams, for example MYSQL_OPT_READ_TIMEOUT is documented to work only for TCP/IP connections and, prior to MySQL 5.1.2, only for Windows. PHP streams may not have this limitation. Please check the streams documentation, if in doubt.
mysqlnd allocates an internal command/network buffer of mysqlnd.net_cmd_buffer_size (in php.ini) bytes for every connection. If a MySQL Client Server protocol command, for example, COM_QUERY ("normal" query), does not fit into the buffer, mysqlnd will grow the buffer to the size required for sending the command. Whenever the buffer gets extended for one connection, command_buffer_too_small will be incremented by one.
If mysqlnd has to grow the buffer beyond its initial size of mysqlnd.net_cmd_buffer_size bytes for almost every connection, you should consider increasing the default size to avoid re-allocations.
The default buffer size is 2048 bytes in PHP 5.3.0. In later versions the default is 4096 bytes. The default can changed either through the php.ini setting mysqlnd.net_cmd_buffer_size or using mysqli_options(MYSQLI_OPT_NET_CMD_BUFFER_SIZE, int size).
It is recommended that the buffer size be set to no less than 4096 bytes because mysqlnd also uses it when reading certain communication packet from MySQL. In PHP 5.3.0, mysqlnd will not grow the buffer if MySQL sends a packet that is larger than the current size of the buffer. As a consequence, mysqlnd is unable to decode the packet and the client application will get an error. There are only two situations when the packet can be larger than the 2048 bytes default of mysqlnd.net_cmd_buffer_size in PHP 5.3.0: the packet transports a very long error message, or the packet holds column meta data from COM_LIST_FIELD (mysql_list_fields() and the meta data come from a string column with a very long default value (>1900 bytes).
As of PHP 5.3.2 mysqlnd does not allow setting buffers smaller than 4096 bytes.
The value can also be set using mysqli_option(link, MYSQLI_OPT_NET_CMD_BUFFER_SIZE, size).
Maximum read chunk size in bytes when reading the body of a MySQL command packet. The MySQL client server protocol encapsulates all its commands in packets. The packets consist of a small header and a body with the actual payload. The size of the body is encoded in the header. mysqlnd reads the body in chunks of MIN(header.size, mysqlnd.net_read_buffer_size) bytes. If a packet body is larger than mysqlnd.net_read_buffer_size bytes, mysqlnd has to call read() multiple times.
The value can also be set using mysqli_optionS(link, MYSQLI_OPT_NET_READ_BUFFER_SIZE, size).