PostgreSQL Bugs

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Bug ID16150
PG Version12.0
OSWindows
Opened2019-12-05 09:17:34+00
Reported byMaxim Votyakov
StatusNew

Body of first available message related to this bug follows.

The following bug has been logged on the website:

Bug reference:      16150
Logged by:          Maxim Votyakov
Email address:      (redacted)
PostgreSQL version: 12.0
Operating system:   Windows
Description:        

Hi guys

Today I found a big problem, I can write a valid UPDATE which put NULL value
in non-null column.

Let's create a domain, two tables and insert 1 row into them:

create domain d_text_not_null as text default '' not null;

create table person (name d_text_not_null);
create table town (name d_text_not_null);

insert into person(name) values ('test');
insert into town(name) values ('test2');

select * from person; -- 1 row with value test  

Now let's try to update person name to null. It failed and it is correct:

update person set name = null; -- SQL Error [23502]: ERROR: domain
d_text_not_null does not allow null values

But now let's try to update person name to with sub-query. It updates a row
without any problem:

update person set name = (select name from town where name = 'wrong'); -- 1
row updated

Let's check data and see the result:

select * from person; -- 1 row with value NULL in non-null column !!!

I think it is very dangerous and important bug and it has to be fixed to not
damage data in databases - if I backup/restore such tables they become
empty.

Messages

DateAuthorSubject
2019-12-05 09:17:34+00PG Bug reporting formBUG #16150: UPDATE set NULL value in non-null columns
2019-12-05 11:35:49+00Mahendra SinghRe: BUG #16150: UPDATE set NULL value in non-null columns
2019-12-05 15:18:10+00Tom LaneRe: BUG #16150: UPDATE set NULL value in non-null columns