Re: ALTER SYSTEM SET command to change postgresql.conf parameters (RE: Proposal for Allow postgresql.conf values to be changed via SQL [review])

On Tue, Aug 20, 2013 at 10:02 PM, Alvaro Herrera
<alvherre(at)2ndquadrant(dot)com> wrote:
> Stephen Frost escribió:
>> * Alvaro Herrera (alvherre(at)2ndquadrant(dot)com) wrote:
>> > Well, all the relative paths in include/includedir directives would be
>> > relative to the directory specified by the -c config_file param, which
>> > makes perfect sense. So the conf.d would work fine in your example.
>>
>> Why would include/includedir directives be relative to where the
>> 'config_file' GUC is set to instead of relative to where all the other
>> GUCs in postgresql.conf are relative to? That is a recipe for
>> confusion, imv.
>>
>> Of course, the current situation is quite terrible anyway, imv. Having
>> the GUCs be relative to whereever the user happens to run pg_ctl from is
>> pretty ugly- not to mention that the commented out 'defaults' won't
>> actually work if you uncomment them because the *actual* default/unset
>> value *is* in the data directory.
>
> Uh? See the docs:
> http://www.postgresql.org/docs/devel/static/config-setting.html#CONFIG-INCLUDES
>
> " ... the postgresql.conf file can contain include directives, ...
> If the file name is not an absolute path, it is taken as relative to
> the directory containing the referencing configuration file."

You are right and I have checked code as well, it works in above
way for include directives.
Now the question I have in mind is that even if we can't
directly use include directive to enable/disable Alter
System and reading of auto file, how would a new GUC
enable_alter_system can solve all the things.
It can allow/disallow Alter System command, but how about
reading of auto file?
If we directly read auto file without considering
enable_alter_system, it can lead to chaos due to some un-safe
values, on the other side if we want to consider
enable_alter_system before reading file, it can complicate the
ProcessConfigFile() code.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com