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

Bruno,
Thanks for your help. I was wondering:

Should we in fact be execing the postmaster as you describe or perhaps pg_ctl
as Lamar's script uses or perhaps
a "new" script that incorporates pg_ctl or postmaster and a signal catching
mechanism. The reason I ask is that

the way that daemontools stops a service - if you want it to - is via the
command

svc opts postgresl :

with opts

-d: Down. If the service is running, send it a TERM signal and then a CONT
signal. After it stops, do not restart it.
-o: Once. If the service is not running, start it. Do not restart it if it
stops.
-p: Pause. Send the service a STOP signal.
-c: Continue. Send the service a CONT signal.
-h: Hangup. Send the service a HUP signal.
-a: Alarm. Send the service an ALRM signal.
-i: Interrupt. Send the service an INT signal.
-t: Terminate. Send the service a TERM signal.
-k: Kill. Send the service a KILL signal.

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?

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 .

Do you agree?

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

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!

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

what is the role of the files

/var/run/postmaster.pid
/var/lock/subsys/postgresql

that Lamar carefully adds and subtracts?


rm -f /var/run/postmaster.pid
rm -f /var/lock/subsys/postgresql

Thanks
Mitchell















On Thursday 08 May 2003 02:40 pm, you wrote:
> On Thu, May 08, 2003 at 14:10:52 -0400,
>
>   mlaks <mlaks@bellatlantic.net> wrote:
> > Thank you for your response Bruno. I agree about the importance of using
> > the lines
> >
> > #!/bin/sh
> > exec 2>&1
> > exec setuidgid postgres /usr/local/pgsql/bin/postmaster -D
> > /usr/local/pgsql/data
> >
> > in the run file. However, what else must we put in as well?
> >
> > My question is to understand the lock files for postgresql so I can deal
> > with the following:
>
> Some of the lock files have to do with the init system. Those can be
> ignored. Postgres also keeps a lock file and that is used to prevent
> two postmasters from running at the same time. You probably don't want
> to have a script remove that lock file, because if there really is
> another postmaster running, starting a second one can be a disaster.
>
>
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