unix_socket

I'm trying to configure postfix to use the postgres database for lookups.

Since I have a localhost based server, I was going to use unix_sockets.

The postgres docs call for only a /directory.

unix_socket_directory (string)

        Specifies the directory of the Unix-domain socket on which the
    server is to listen for connections from client applications. The
    default is normally /tmp, but can be changed at build time.

The postfix docs call for a /directory/name.

               inet: for TCP connections (default).  Example:
                   hosts = host1.some.domain host2.some.domain
                   hosts = unix:/file/name

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How do I get this sorted out so that I can make a unix connection?