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

On Fri, Aug 23, 2013 at 06:41:04PM +0530, Amit Kapila wrote:
> > Not with this proposal...  If it's fixed then it makes no sense to make it
> > look like it can be modified.
> 
>    This proposal is to have a special include which user can only use
> for enable/disable
>    which means he can remove symbol '#' or add '#'.
>    We cannot stop user from changing file name or add some different
> location, but that can lead to problems.
>    We can have a note on top of this include indicating it is only for
> enable/disable.

Note, my whole purpose for suggesting something like:

include_auto_conf_file    postgresql.auto.conf

is because I want the file location to be configurable. If I put in my
configuration:

include_auto_conf_file    /etc/postgresql/9.4/postgresql.auto.conf

it better put the options there. And if I comment the line out ALTER
SYSTEM should stop working.  If I put it at the beginning of the config
then any other option in the file will override it (which we can detect
and warn about).  If I put it at the end of the file, ALTER SYSTEM
overrides any statically configured options.

And I can imagine hosting providers putting the configuration for
memory usage, shared library directories and other such options after,
and options like cpu_cost, enable_merge_join, etc before.  That way
they have fine grained control over which options the user can set and
which not.

>    I think if we add more meaning to it, like allow user to change it,
> handling and defining of that will be bit complex.

Letting the user configure the location seems like common curtesy. Note
this line isn't in itself a GUC, so you can't configure it via ALTER
SYSTEM.

Have a nice day,
-- 
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> He who writes carelessly confesses thereby at the very outset that he does
> not attach much importance to his own thoughts.
   -- Arthur Schopenhauer