Re: Mark all GUC variable as PGDLLIMPORT

On 02/13/22 15:16, Tom Lane wrote:
> That seems like about 10X more complexity than is warranted,
> not only in terms of the infrastructure required, but also in
> the intellectual complexity around "just when could that value
> change?"
> 
> Why not just provide equivalents to GetConfigOption() that can
> deliver int, float8, etc values instead of strings?

And repeat the bsearch to find the option every time the interested
extension wants to check the value, even when what it learns is that
the value has not changed? And make it the job of every piece of
interested extension code to save the last-retrieved value and compare
if it wants to detect that it's changed? When the GUC machinery already
has code that executes exactly when a value is being supplied for
an option?

Clearly I'm not thinking here of the GUCs that are read-only views of
values that are determined some other way. How many of those are there
that are mutable, and could have their values changed without going
through the GUC mechanisms?

Also, I think there are some options that are only represented by
an int, float8, etc., when shown, but whose native internal form
is something else, like a struct. I was definitely contemplating
that you could 'subscribe' to one of those too, by passing the
address of an appropriate struct. But of course a GetConfigOption()
flavor could work that way too.

Regards,
-Chap