TODO item for pg_ctl and server detection

While I am working on pg_ctl, I saw this TODO item:

Have the postmaster write a random number to a file on startup that
pg_ctl checks against the contents of a pg_ping response on its initial
connection (without login)

This will protect against connecting to an old instance of the
postmaster in a different or deleted subdirectory.

http://archives.postgresql.org/pgsql-bugs/2009-10/msg00110.php
http://archives.postgresql.org/pgsql-bugs/2009-10/msg00156.php

Based on our new PQPing(), do we ever want to implement this or should I
remove the TODO item? It seems this would require a server connection,
which is something we didn't want to force pg_ctl -w to do in case
authentication is broken.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +