Re: How to detect if Postgres needs a restart when configuration changes

On Wed, Oct 1, 2014 at 6:56 AM, Peter Eisentraut <peter_e(at)gmx(dot)net> wrote:

> On Tue, 2014-09-30 at 18:51 -0600, Jason Mathis wrote:
> > How are you automating? Have you looked at puppet or anything? Puppet
> > labs maintains a postgresql module that has all that baked in. Check
> > it out at least it can give you some ideas.
>
> Their "idea" is to maintain a hard-coded list about which parameter
> changes need a restart, and their list is wrong.
>

I'm deploying Postgres with Ansible, so Puppet doesn't help.

The idea of maintaining a list of parameters which require a restarts is ok
for automation, since you usually only change a few of them. I also have a
list of those parameters which can be changed by Ansible and I would like
to detect if any of them changed, so I know I need to restart. Or it would
be even better if Postgres can tell me if it requires a restart to apply
all parameter changes, something like when you send SIGHUP and in the log
it tells you that a parameter can only be changed after restart. But I can
see that doesn't exist.

I have a relatively easy solution for this with Ansible. Ansible saves the
values of all parameters which require a restart in one file and I just
check if that file changed, but the problem with this is that if I change
this file for any other reason, it could restart Postgres even if it
doesn't need a restart. The right way is to parse the postgresql.conf and
compare the values with pg_settings, but I was hoping to avoid that.