As I'm moving things to a new VPS, I'm setting up my PHP scripts on the new VPS to look at the old VPS for MySQL. This will let me transition slowly, and when everything's ready to go then I can move MySQL over last.

In doing this, I discovered that mysqli_connect() doesn't have a "flag" option (like MYSQLI_CLIENT_COMPRESS); if I want that then I need to use mysqli_real_connect().

The docs show that I need to use these params:

Host
Username
Password
Database name
Port
Socket
Flags

[php.net...]

I want to use a flag, but I don't know the port or socket. How do I tell it to "use the default"?

Failing that, how do I determine the actual port and socket being used so that I can plug them in manually?

Here's the code I'm using:

$dbh = mysqli_init();
if (!$dbh) { die('mysqli_init failed'); }

// I don't know if I really need these, but it's in the docs so I thought I'd test it
if (!mysqli_options($dbh, MYSQLI_INIT_COMMAND, 'SET AUTOCOMMIT = 0')) { die('Setting MYSQLI_INIT_COMMAND failed'); }
if (!mysqli_options($dbh, MYSQLI_OPT_CONNECT_TIMEOUT, 5)) { die('Setting MYSQLI_OPT_CONNECT_TIMEOUT failed'); }

// I'm just plugging in a whitespace and a comma until I figure out how to do this properly
if (!mysqli_real_connect($dbh, '123.45.67.89', '[USERNAME]', '[PASSWORD]', '[DATABASE_NAME]', , , MYSQLI_CLIENT_COMPRESS)) {
 // do error stuff
}