Re: exposing pg_controldata and pg_config as functions

On 9/6/15 3:34 PM, Joe Conway wrote:
> On 09/02/2015 02:54 PM, Alvaro Herrera wrote:
>> Josh Berkus wrote:
>>> On 09/02/2015 02:34 PM, Alvaro Herrera wrote:
>>>> I think trying to duplicate the exact strings isn't too nice an
>>>> interface.
>>>
>>> Well, for pg_controldata, no, but what else would you do for pg_config?
>>
>> I was primarily looking at pg_controldata, so we agree there.
>>
>> As for pg_config, I'm confused about its usefulness -- which of these
>> lines are useful in the SQL interface? Anyway, I don't see anything
>> better than a couple of text columns for this case.
>
> There are production environments where even the superuser has no
> direct, local, command line access on production database servers

But then they also have no use for the information that pg_config prints
out.

> and the
> only interface for getting information from postgres is via a database
> connection. So to the extent pg_config and pg_controldata command line
> binaries are useful, so is the ability to get the same output via SQL.
>
> Given that, my own feeling is that if we provide a SQL interface at all,
> it ought to be pretty much the exact same output as the command line
> programs produce.

That argument makes no sense to me.

Again, we need to think about what actual use there is for this
information. Just because the information exists somewhere, but you
can't access it, doesn't mean we just need to copy it around.