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

postgres=# drop function im_now(anyelement) ;

DROP FUNCTION

postgres=# drop function im_now ;

DROP FUNCTION

postgres=# drop table t1;

DROP TABLE

postgres=# 

postgres=# create or replace function im_now (float8 default random()) returns timestamptz as $$  

postgres$#   select now();  

postgres$# $$ language sql strict immutable; 

CREATE FUNCTION

postgres=# 

postgres=# create table t1 (id int primary key, c1 int, info text, crt_time timestamp, 

postgres(# mod_time timestamp GENERATED ALWAYS AS (im_now()) stored); 

CREATE TABLE

postgres=# insert into t1 (id, c1, info, crt_time) values (1,1,'test', now());  

INSERT 0 1

postgres=# 

postgres=# select * from t1; 

 id | c1 | info |          crt_time          |          mod_time          

----+----+------+----------------------------+----------------------------

  1 |  1 | test | 2021-05-27 10:43:32.278616 | 2021-05-27 10:43:32.278616

(1 row)

postgres=# update t1 set info='a' where id=1;

UPDATE 1

postgres=# select * from t1;

 id | c1 | info |          crt_time          |          mod_time          

----+----+------+----------------------------+----------------------------

  1 |  1 | a    | 2021-05-27 10:43:32.278616 | 2021-05-27 10:43:32.278616

(1 row)

postgres=# update t1 set info='a' where id=1;

UPDATE 1

postgres=# select * from t1;

 id | c1 | info |          crt_time          |          mod_time          

----+----+------+----------------------------+----------------------------

  1 |  1 | a    | 2021-05-27 10:43:32.278616 | 2021-05-27 10:43:32.278616

(1 row)

postgres=# select im_now();

            im_now             

-------------------------------

 2021-05-27 10:44:03.749108+08

(1 row)

postgres=# select im_now();

            im_now             

-------------------------------

 2021-05-27 10:44:04.509058+08

(1 row)

postgres=# select im_now();

            im_now             

-------------------------------

 2021-05-27 10:44:06.781393+08

(1 row)

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