Re: Postgresql goes down need to restart (redhat postgresql service script) lock files removal avoid 2 postmasters

On Thu, May 08, 2003 at 14:39:08 -0400,
  mlaks <mlaks@bellatlantic.net> wrote:
>
> now we would not want to kill the postmaster, of course. But should we even be
> TERM'ing the postmaster? I dont know. What do the Postgresql Gurus say?

I regularly use svc -d to shutdown postmaster and svc -u to restart it.
This works just fine.

> Moreover, if we agree that we need to imbed pg_ctl or postmaster in a script
> to handle the above things, it should be doable to handle all of the assorted
> other files if they are neccesary to handle .

You don't have to do that.

> Also what would be the problem in checking for the existence of a postmaster
> and if none exists then killing the lock files.

I would be very leary of putting this in a script. postmaster already does
this and trying to be smarter than it might cause you a lot of grief.

> My main problem is that I have machines that get creamed by power surges, and
> then wont restart postgresql on reboot of the system because of the damn lock
> files. I really want to deal with them up front!

Most of the time when I have unscheduled shutdowns postgres comes up without
problem. I don't remember if I have had any since I switched to using
supervise though. I have had more issues with someone needing to answer
a question from fsck from the console than postgresql not coming up.

> MOreover can you tell me more about what init uses the locks for?

To tell if the service is already running or not.

>
> what is the role of the files
>
> /var/run/postmaster.pid
> /var/lock/subsys/postgresql
>
> that Lamar carefully adds and subtracts?

I don't know exactly, but I would expect that the pid file is a lock for
the service and that the subsys file is a lock to keep two init scripts
from running for the same time for the same service.