USE tpch1;
drop table if exists bug2835;
create table bug2835 (c1 int, c2 varchar(6), c3 varchar(20), c4 datetime)engine=columnstore;
insert into bug2835 values (1, 'one', 'one', '2010-01-01'), (2, 'two', 'two', '2010-02-02'), (null, null, null, null);
select c1, c2, c3, ifnull(c1,"z"), ifnull(c2,''), ifnull(c3,''), ifnull(c4,'') from bug2835;
c1	c2	c3	ifnull(c1,"z")	ifnull(c2,'')	ifnull(c3,'')	ifnull(c4,'')
1	one	one	1	one	one	2010-01-01 00:00:00
2	two	two	2	two	two	2010-02-02 00:00:00
NULL	NULL	NULL	z			
drop table bug2835;