Re: Fix GUC_NO_SHOW_ALL test scenario in 003_check_guc.pl

On Mon, Feb 13, 2023 at 11:27:58AM +0900, Kyotaro Horiguchi wrote:
> I think currently the output by --describe-config can be used only for
> consulting while editing a (possiblly broken) config file. Thus I
> think it's no use showing GIC_DISALLOW_IN_FILE items there unless we
> use help_config() for an on-session use.
>
> On the other hand, don't we need to remove the condition
> GUC_NOT_IN_SAMPLE from displayStruct? I think that help_config()
> should show a value if it is marked as !GUC_DISALLOW_IN_FILE even if
> it is GUC_NOT_IN_SAMPLE. I'm not sure whether there's any variable
> that are marked that way, though.

As in marked with GUC_NOT_IN_SAMPLE but not GUC_DISALLOW_IN_FILE?
There are quite a lot, developer GUCs being one (say
ignore_invalid_pages). We don't want to list them in the sample file
so as common users don't play with them, still they make sense if
listed in a file.

If you add a check meaning that GUC_DISALLOW_IN_FILE implies
GUC_NOT_IN_SAMPLE, where one change would need to be applied to
config_file as all the other GUC_DISALLOW_IN_FILE GUCs already do
that, you could remove GUC_DISALLOW_IN_FILE. However,
GUC_NOT_IN_SAMPLE should be around to not expose options, we don't
want common users to know too much about.

The question about how much people rely on --describe-config these
days is a good one, so perhaps there could be an argument in removing
GUC_NOT_IN_SAMPLE from the set. TBH, I would be really surprised that
anybody able to use a developer option writes an configuration file in
an incorrect format and needs to use this option, though :)
--
Michael