Re: Improve documentation for current_setting function

On Fri, Feb 22, 2019 at 11:43:54AM +0200, Eugen Konkov wrote:
> 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

Yes, I saw that recent thread.

> 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. =(

Understood.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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