Usually I just bung in 127 or localhost in order to connect up to my DB. However, if you aren’t allowing remote connections, then running on a unix socket is much faster and skips all the networking overhead involved with TCP/IP.
So! To use a socket, you use a DSN for the connection. I’ve done this a few times, but I keep forgetting the syntax, sop here it is, solely for my own memory’s sake: