Closed
Description
Describe the bug
Given a column with null values, if you group by that column the null values are lost
To Reproduce
Input:
c1
----
0
3
1
3
(5 rows)
And run SELECT COUNT(*), c1 FROM test GROUP BY c1
Actual result
"+-----------------+----+",
"| COUNT(UInt8(1)) | c1 |",
"+-----------------+----+",
"| 2 | 3 |",
"| 2 | 0 |", <-- NOTE there is only a single actual value of 0 in the input (the other is NULL)
"| 1 | 1 |",
"+-----------------+----+",
Expected behavior
Here is the correct answer according to postgres (note the row for c1 is NULL):
alamb=# SELECT COUNT(*), c1 FROM test GROUP BY c1;
count | c1
-------+----
1 |
2 | 3
1 | 0
1 | 1
(4 rows)
Additional context
Discovered while playing around with #781
Here is the entire reproducer in postgres
alamb=# drop table test;
DROP TABLE
alamb=# create table test (c1 int);
CREATE TABLE
alamb=# insert into test values(0);
INSERT 0 1
alamb=# insert into test values(3);
INSERT 0 1
alamb=# insert into test values(NULL);
INSERT 0 1
alamb=# insert into test values(1);
INSERT 0 1
alamb=# insert into test values(3);
INSERT 0 1
alamb=# SELECT COUNT(*), c1 FROM test GROUP BY c1;
count | c1
-------+----
1 |
2 | 3
1 | 0
1 | 1
(4 rows)