Re: allow online change primary_conninfo

Hi

> I would recommend waiting for the conclusion of other thread before
> moving on with this one.
Agreed.
I mark this patch as Waiting on Author. Not quite correct for waiting another discussion, but most suitable.

> We could also consider using
> the show hook function of a parameter to print its value in such logs.
But show hook also affects "show primary_conninfo;" command and pg_settings.value
I already marked primary_conninfo as GUC_SUPERUSER_ONLY. I doubt if we need hide some connection info even from superuser.
Also this hook would be a bit complicated, i found suitable code only in libpqrcv_get_conninfo after establishing connect

regards, Sergei