Xing Guo <higuoxing@gmail.com> writes:
> Thanks for your comments. I have updated the patch accordingly.
I'm leery of accepting this patch, as I see no reason that we
should consider it valid for an extension to have a string GUC
with a boot_val of NULL.
I realize that we have a few core GUCs that are like that, but
I'm pretty sure that every one of them has special-case code
that initializes the GUC to something non-null a bit later on
in startup. I don't think there are any cases where a string
GUC's persistent value will be null, and I don't like the
idea of considering that to be an allowed case. It would
open the door to more crash situations, and it brings up the
old question of how could a user tell NULL from empty string
(via SHOW or current_setting() or whatever). Besides, what's
the benefit really?
regards, tom lane