Horton

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

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Stephen Frost <sfrost@snowman.net>, Tom Lane <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>, Dimitri Fontaine <dimitri@2ndquadrant.fr>, Andres Freund <andres@2ndquadrant.com>, Josh Berkus <josh@agliodbs.com>, Fujii Masao <masao.fujii@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2013-08-21T04:40:32Z
Lists: pgsql-hackers 
On Tue, Aug 20, 2013 at 10:02 PM, Alvaro Herrera
<alvherre@2ndquadrant.com> wrote:
> Stephen Frost escribió:
>> * Alvaro Herrera (alvherre@2ndquadrant.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