## Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

MySQLi Configuration Options
Name | Default | Changeable | Changelog
--- | --- | --- | ---
mysqli.allow_local_infile | "0" | PHP_INI_SYSTEM | Available as of PHP 5.2.4. Before PHP 7.2.16 and 7.3.3 the default was "1".
mysqli.allow_persistent | "1" | PHP_INI_SYSTEM | Available as of PHP 5.3.0.
mysqli.max_persistent | "-1" | PHP_INI_SYSTEM | Available as of PHP 5.3.0.
mysqli.max_links | "-1" | PHP_INI_SYSTEM |
mysqli.default_port | "3306" | PHP_INI_ALL |
mysqli.default_socket | NULL | PHP_INI_ALL |
mysqli.default_host | NULL | PHP_INI_ALL |
mysqli.default_user | NULL | PHP_INI_ALL |
mysqli.default_pw | NULL | PHP_INI_ALL |
mysqli.reconnect | "0" | PHP_INI_SYSTEM |
mysqli.rollback_on_cached_plink | TRUE | PHP_INI_SYSTEM | Available as of PHP 5.6.0.

For further details and definitions of the preceding PHP_INI_* constants, see the chapter on configuration changes.

Here's a short explanation of the configuration directives.

`mysqli.allow_local_infile` integer

  Allow accessing, from PHP's perspective, local files with LOAD DATA statements

`mysqli.allow_persistent` integer

  Enable the ability to create persistent connections using mysqli_connect().

`mysqli.max_persistent` integer

  Maximum of persistent connections that can be made. Set to 0 for unlimited.

`mysqli.max_links` integer

  The maximum number of MySQL connections per process.

`mysqli.default_port` integer

  The default TCP port number to use when connecting to the database server if no other port is specified. If no default is specified, the port will be obtained from the MYSQL_TCP_PORT environment variable, the mysql-tcp entry in /etc/services or the compile-time MYSQL_PORT constant, in that order. Win32 will only use the MYSQL_PORT constant.

`mysqli.default_socket` string

  The default socket name to use when connecting to a local database server if no other socket name is specified.

`mysqli.default_host` string

  The default server host to use when connecting to the database server if no other host is specified. Doesn't apply in safe mode.

`mysqli.default_user` string

  The default user name to use when connecting to the database server if no other name is specified. Doesn't apply in safe mode.

`mysqli.default_pw` string

  The default password to use when connecting to the database server if no other password is specified. Doesn't apply in safe mode.

`mysqli.reconnect` integer

  Automatically reconnect if the connection was lost.

  > Note: This php.ini setting is ignored by the mysqlnd driver.

`mysqli.rollback_on_cached_plink` bool

  If this option is enabled, closing a persistent connection will rollback any pending transactions of this connection before it is put back into the persistent connection pool. Otherwise, pending transactions will be rolled back only when the connection is reused, or when it is actually closed.

Users cannot set MYSQL_OPT_READ_TIMEOUT through an API call or runtime configuration setting. Note that if it were possible there would be differences between how libmysqlclient and streams would interpret the value of MYSQL_OPT_READ_TIMEOUT.