Re: Restart after poweroutage

Jon Lapham <lapham(at)jandr(dot)org> writes:
> I recently had another electrical power outage that left my machine
> unable to restart postgresql. I had previously reported this a while ago:

> http://archives.postgresql.org/pgsql-general/2005-04/msg01286.php

> Anyway, because I have seen this problem before, I knew exactly what the
> solution to the problem was (delete the postmaster.pid file),

As was pointed out to you in the discussion subsequent to that message,
this is not a good automatic response, and it should not be necessary at
all with a post-8.0 postmaster.

> FATAL: pre-existing shared memory block (key 5432001, ID 65536) is
> still in use

This is extremely odd, because a shared memory block could not possibly
have survived a reboot. Too bad you have destroyed the evidence,
because I would like to know what really happened there. Is it possible
that you have somehow managed to try to start the postmaster twice
during your system boot cycle? If you do have two postmasters running
in that data directory right now, you are in deep trouble :-(

> I can reproduce this problem in v8.1.4 by these simple steps:

This is not "reproducing the problem", this is merely demonstrating that
the postmaster will fail to overwrite a root-owned postmaster.pid file.

regards, tom lane