Thank you Tom!
Your comment
"NULL doesn't have semantics that are visibly different from an empty
string" is exactly what I want to confirm :-)
On 11/2/23, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I wrote:
>> Hmm ... if we're doing it ourselves, I suppose we've got to consider
>> it supported :-(. But I'm still wondering how many seldom-used
>> code paths didn't get the message. An example here is that this
>> could lead to GetConfigOptionResetString returning NULL, which
>> I think is outside its admittedly-vague API spec.
>
> After digging around for a bit, I think part of the problem is a lack
> of a clearly defined spec for what should happen with NULL string GUCs.
> In the attached v3, I attempted to remedy that by adding a comment in
> guc_tables.h (which is maybe not the best place but I didn't see a
> better one). That led me to a couple more changes beyond what you had.
>
> It's possible that some of these are unreachable --- for example,
> given that a NULL could only be the default value, I'm not sure that
> the fix in write_one_nondefault_variable is a live bug. But we ought
> to code all this stuff defensively, and most of it already was
> NULL-safe.
>
> regards, tom lane
>
>
--
Best Regards,
Xing
