Re: BUG #15646: Inconsistent behavior for current_setting/set_config

Joe Conway <mail(at)joeconway(dot)com> writes:
> On 2/20/19 11:10 AM, PG Bug reporting form wrote:
>> But current behavior returns empty string instead of NULL (the initial
>> value) after transaction is rolled back. When I restart session, NULL is
>> returned again as it is expected.

> This has been discussed before and dismissed:
> https://www.postgresql.org/message-id/flat/56842412.5000005%40joeconway.com
> Personally I agree it is a bug, but I am not sure you will get much
> support for that position.

The fact that we allow undeclared user-defined GUCs at all is a bug IMO.
We need to find a way to replace that behavior with something whereby
the name and type of a parameter are declared up-front before you can
set it.

regards, tom lane