Re:Re: BUG #17036: generated column cann't modifyed auto when update

The generated column can be used to automatically generate the modified timestamp of a tuple, but PG 12 currently supports this scenario. PG 13 has started to change its behavior, which makes our application need to be modified. This is the first time I have ever seen a PG upgrade kill a nice feature.

--

公益是一辈子的事,I'm Digoal,Just Do It.

在 2021-05-27 10:33:40，"David G. Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com> 写道：

On Wednesday, May 26, 2021, 德哥 <digoal(at)126(dot)com> wrote:

And immutable function is stable when parameter not change, when parameter changed , the immutable function will recall and recompute.
but in PG 13 and PG 14 , it is also wrong.

```
create or replace function im_now (anyelement) returns timestamptz as $$
select now();
$$ language sql strict immutable;

create table t1 (id int primary key, c1 int, info text, crt_time timestamp,
mod_time timestamp GENERATED ALWAYS AS (im_now(t1)) stored);

This seems to be related to this already reported bug (the similar one I noted in my other reply).

https://www.postgresql.org/message-id/CAM_DEiWR2DPT6U4xb-Ehigozzd3n3G37ZB1%2B867zbsEVtYoJww%40mail.gmail.com

David J.