Обсуждение: Description of SIGHUP GUC parameters

Currently, the standard boilerplate description of a SIGHUP parameter
is

        This option can only be set at server start or in the
        <filename>postgresql.conf</filename> file.

We've heard from more than one person who found this confusing ---
frequently it's misread as saying that the parameter cannot be changed
after postmaster start.  Doubtless this is partly because the
boilerplate phrase for a POSTMASTER parameter is

        This option can only be set at server start.

However, previous discussions have dried up without coming up with a
better phrase.  It occurred to me today that this might work better:

        This option can only be set in the <filename>postgresql.conf</>
        file or on the server command line.

I think mentioning the config file first is important to focus attention
on that.  The only other way to set these parameters is via command-line
switches, so we should just say that rather than emphasizing the "server
start time" aspect of it, which is exactly what not to emphasize.

Comments?

            regards, tom lane

On Sat, 2006-01-21 at 14:46 -0500, Tom Lane wrote:
> Currently, the standard boilerplate description of a SIGHUP parameter
> is
>
>         This option can only be set at server start or in the
>         <filename>postgresql.conf</filename> file.
>
> We've heard from more than one person who found this confusing ---
> frequently it's misread as saying that the parameter cannot be changed
> after postmaster start.  Doubtless this is partly because the
> boilerplate phrase for a POSTMASTER parameter is
>
>         This option can only be set at server start.
>
> However, previous discussions have dried up without coming up with a
> better phrase.  It occurred to me today that this might work better:
>
>         This option can only be set in the <filename>postgresql.conf</>
>         file or on the server command line.
>
> I think mentioning the config file first is important to focus attention
> on that.  The only other way to set these parameters is via command-line
> switches, so we should just say that rather than emphasizing the "server
> start time" aspect of it, which is exactly what not to emphasize.

Just seen this again today and agree its confusing.

<wildassertion>I think most people think that all parameters can only be
set at server start, until they have dug deeper. Most other systems
software requires a restart to pick up new parameters</wildassertion>

Why not simply use the technical phrase: "SIGHUP" etc. We can just say
'these terms are shorthand for "......" '

I'm not crazy about the terms but at least it is explicit and accurate.
It would also allow us to have a much longer description of all of the
implications and difficulties of each mode.

Best Regards, Simon Riggs

Simon Riggs <simon@2ndquadrant.com> writes:
> Why not simply use the technical phrase: "SIGHUP" etc. We can just say
> 'these terms are shorthand for "......" '

> I'm not crazy about the terms but at least it is explicit and accurate.
> It would also allow us to have a much longer description of all of the
> implications and difficulties of each mode.

We have all that in the introductory section; the references made in the
per-variable descriptions really have no impact on how verbose the
introductory text is ...

            regards, tom lane