Re: PGDLLEXPORTing all GUCs?

On Wed, May 7, 2014 at 1:08 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> On Wed, May 7, 2014 at 12:21 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> If Craig has a concrete argument why all GUCs should be accessible
>>> to external modules, then let's see it (after which we'd better debate
>>> exposing the few that are in fact static in guc.c).
>
>> I think there's actually a very good reason to think that GUCs are
>> good candidates for this treatment, which is that, by definition, the
>> GUC is a public interface: you can change it with a SET command.
>
> Sure, and we provide public APIs for accessing/setting GUCs. The SET
> side of that is most emphatically *not* "just set the C variable".
> Yeah, you can get away with reading them like that, assuming you want
> the internal representation not the user-visible one. In any case,
> I've not heard the use-case why all (and only) GUCs might need to be
> readable in that way.

My experience is that GUCs are a common thing to want expose to
extensions, and that C code usually wants the internal form, not the
string form. I'm not arguing that nothing else needs to be exposed,
but if there's a better argument possible for exposing the GUC
variables than the fact that a bunch of people with experience
developing PostgreSQL extensions view that as a real need, I can't
think what it is.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
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