Re: Should we eliminate or reduce HUP from docs?

From: "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>
To: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
Cc: "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Should we eliminate or reduce HUP from docs?
Date: 2017-03-10 22:42:08
Message-ID: CAKFQuwYKhDdn+Ed1CNY346j-uiJW6saHsjtY7YBFoErWxrm8-w@mail.gmail.com
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On Fri, Mar 10, 2017 at 3:28 PM, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
wrote:

> David G. Johnston wrote:
> > On Fri, Mar 10, 2017 at 1:02 PM, Alvaro Herrera <
> alvherre(at)2ndquadrant(dot)com>
> > wrote:
>
> > > There are several ways to cause a config file reload (pg_ctl reload,
> > > pg_reload_conf, direct SIGHUP). We could have a section in docs
> listing
> > > them all, and then all the other places that say a reload needs to
> occur
> > > simply refer the reader to that section.
> >
> > ​19.1.2 contains a fairly comprehensive coverage of the topic ​- but
> > postgres.conf is not the only thing that gets reloaded. Specifically,
> > "Client Authentication" (chapter 20) is also affected.
>
> I think we could split 19.1.2 in two parts, where the first one is the
> current content minus the paragraph "The configuration file is reread".
> We'd create "19.1.3 Configuration File Reloads" to contain that
> paragraph, perhaps not with the exact current wording.
>

​If only 19 and 20 need it I would say its a coin-toss.​

> > One theory would be to consider "configuration reload" part of "18.
> Server
> > ... Operation" and document the mechanics there with forward references
> to
> > 19/Configuration and 20/Authentication.
>
> Dunno. Given that other configuration elements such as config file
> placement are already in chapter 19, it seems strange to put reloading
> behavior in 18.
>
>
​It wouldn't be hateful to cross link to 19 from 20 - but assuming
pg_reload_conf() impacts pg_hba.conf​ (I don't know off-hand) the paragraph

"""
The pg_hba.conf file is read on start-up and when the main server process
receives a SIGHUP signal. If you edit the file on an active system, you
will need to signal the postmaster (using pg_ctl reload or kill -HUP) to
make it re-read the file.
"""

is incomplete.

Is "kill" portable?

The order or some of these items is interesting but given the general lack
of field complaints and questions it mustn't be confusion inducing. Even
this thread isn't an actual complaint but rather concern about signals in
general. Pulling the relevant paragraph out to its own section in 19.1 was
my first reaction as well and has the merit of simplicity.

David J.

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