Establishes a persistent connection to a MySQL server.
mysql_pconnect() acts very much like mysql_connect() with two major differences.
First, when connecting, the function would first try to find a (persistent) link that's already open with the same host, username and password. If one is found, an identifier for it will be returned instead of opening a new connection.
Second, the connection to the SQL server will not be closed when the execution of the script ends. Instead, the link will remain open for future use (mysql_close() will not close links established by mysql_pconnect()).
This type of link is therefore called 'persistent'.
The MySQL server. It can also include a port number. e.g. "hostname:port" or a path to a local socket e.g. ":/path/to/socket" for the localhost.
If the PHP directive mysql.default_host is undefined (default), then the default value is 'localhost:3306'
The username. Default value is the name of the user that owns the server process.
The password. Default value is an empty password.
The client_flags parameter can be a combination of the following constants: MYSQL_CLIENT_SSL, MYSQL_CLIENT_COMPRESS, MYSQL_CLIENT_IGNORE_SPACE or MYSQL_CLIENT_INTERACTIVE.
Note: Note, that these kind of links only work if you are using a module version of PHP. See the Persistent Database Connections section for more information.
Using persistent connections can require a bit of tuning of your Apache and MySQL configurations to ensure that you do not exceed the number of connections allowed by MySQL.
Note: You can suppress the error message on failure by prepending a @ to the function name.