Is it expected behavior that MIN() window function in MariaDB/MySQL can return a non-null value from a window with only null values?

Question

A minimal example for MariaDB (reproduced with with 10.2 and latest):

DROP TABLE IF EXISTS t;
CREATE TABLE t
(
 id int unsigned not null,
 value int unsigned null
);
INSERT INTO t
values (1, null);
CREATE OR REPLACE VIEW v
as
select 1 as id,
 ifnull(null, 999) as value
from t
;
select *,
 MIN(t.value) over (PARTITION BY t.id) as min_t,
 MIN(v.value) over (PARTITION BY t.id) as min_v
from t
 left join v
 on t.id > v.id
;

It returns

id value id value min_t min_v
1 null null null null 999

bit I would expect it to return

id value id value min_t min_v
1 null null null null null <-- null instead of 999

because there is only a single row and it has value = null in the window for MIN function. Sure, it is backed by a ifnull() in view's select, but the resulting set has null from a left join with no corresponding row, so it shouldn't be handled by ifnull() in the view, right?

Can this be considered a bug?

MySQL sqlfiddle example comparing using a view vs using nested selects. Nested selects produce the result I expect, using view doesn't.

Comparing to other RDBMS:

Oracle example: both ways work as I expect.

PostgreSQL example: both ways work as I expect.

• ypercubeᵀᴹ: Looks like a bug.
• ypercubeᵀᴹ: Have you tested with the latest version? Try on dbfiddle.uk that has MYSQL 8 and Maria 10.4
• jojman: @ypercubeTM Thanks for the suggestion. MySQL 8 works properly. MariaDB 10.3 has incorrect behavior, and MariaDB 10.4 (latest) just fails to execute the query. I ran the query in a MariaDB 10.4.12 docker container, and there is still incorrect behavior.
• ypercubeᵀᴹ: I suggest you should send a bug report to MariaDB list then. And feel free to self answer here that this is a bug.

Answer 1

Reported this as a bug to MariaDB bug tracker:

https://jira.mariadb.org/browse/MDEV-21874