Re: Improve documentation for current_setting function

Hello Bruce,

> How do you like the attached patch, which clarifies this?

>>in which case a missing parameter returns
>>! NULL.

not always. It can be NULL or empty string. It depends if the current
session is new or after finished transaction which makes 'local' changes
to setting

Take into account these steps: https://www.postgresql.org/message-id/15646-0d3caee9f6266f60%40postgresql.org

From my user point of view. if the boot value before transaction was
NULL then after transaction it MUST stay NULL and not empty string.

This will be consistent with that if I open new parallel session it
will return NULL.

Also I see NULL value (if setting was not defined) is useful.

Also this:
set_config( 'my.name', NULL )
must set 'my.name' to NULL or must issue warning about NULL is turned
into empty string.

Personally I dislike that NULL is converted to empty string. This
looks ugly. =(

--
Best regards,
Eugen Konkov