Installation
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Installing/Configuring
PHP Manual

## Runtime Configuration

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

MySQL Configuration Options
Name | Default | Changeable | Changelog
--- | --- | --- | ---
mysql.allow_persistent | "1" | PHP_INI_SYSTEM |
mysql.max_persistent | "-1" | PHP_INI_SYSTEM |
mysql.max_links | "-1" | PHP_INI_SYSTEM |
mysql.trace_mode | "0" | PHP_INI_ALL | Available since PHP 4.3.0.
mysql.default_port | NULL | PHP_INI_ALL |
mysql.default_socket | NULL | PHP_INI_ALL | Available since PHP 4.0.1.
mysql.default_host | NULL | PHP_INI_ALL |
mysql.default_user | NULL | PHP_INI_ALL |
mysql.default_password | NULL | PHP_INI_ALL |
mysql.connect_timeout | "60" | PHP_INI_ALL | PHP_INI_SYSTEM in PHP <= 4.3.2. Available since PHP 4.3.0.

For further details and definitions of the PHP_INI_* constants, see the php.ini directives.

Here's a short explanation of the configuration directives.

`mysql.allow_persistent` boolean

  Whether to allow persistent connections to MySQL.

`mysql.max_persistent` integer

  The maximum number of persistent MySQL connections per process.

`mysql.max_links` integer

  The maximum number of MySQL connections per process, including persistent connections.

`mysql.trace_mode` boolean

  Trace mode. When mysql.trace_mode is enabled, warnings for table/index scans, non free result sets, and SQL-Errors will be displayed. (Introduced in PHP 4.3.0)

`mysql.default_port` string

  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.

`mysql.default_socket` string

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

`mysql.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 SQL safe mode.

`mysql.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 SQL safe mode.

`mysql.default_password` string

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

`mysql.connect_timeout` integer

  Connect timeout in seconds. On Linux this timeout is also used for waiting for the first answer from the server.

Installation
Resource Types
Installing/Configuring
PHP Manual