Re: Config reload/restart preview

On Thu, Jun 20, 2013 at 2:54 PM, Dimitri Fontaine
<dimitri(at)2ndquadrant(dot)fr> wrote:
> Magnus Hagander <magnus(at)hagander(dot)net> writes:
>>> Should we have a way of previewing changes that would be applied if we
>>> reloaded/restarted the server?
>>
>> Yes, we should.
>
> +1
>
>> This would go well with something I started working on some time ago
>> (but haven't actually gotten far on at all), which is the ability for
>> pg_ctl to be able to give feedback at all. Meaning a "pg_ctl reload"
>> should also be able to tell you which parameters were changed, without
>> having to go to the log. Obviously that's almost exactly the same
>> feature.
>
> It could probably connect to the server and issue the SQL command to
> reload, and that one could probably get enhanced to return modified
> variable as NOTICE, or be run with the right client_min_message:
>
> SELECT pg_reload_conf();
>
> The pg_ctl client would then have to know to display the messages sent
> back by the server.

The problem with that is that now you must *always* have your system
set up to allow the postgres user to log in in pg_hba.conf or it
fails.

But yes, one option would be to use SQL instead of opening a socket.
Maybe that's a better idea - have pg_ctl try to use that if available,
and if not send a regular signal and not try to collect the output.

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/