[KYLIN-2948] Count a column returns the same result as count(*) even if this column has NULL

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Duplicate
• Affects Version/s: v2.1.0
• Fix Version/s: v2.4.0
• Environment: CentOS 7
• Assignee: Unassigned
• Reporter: DeXin
• Created: 19/Oct/17 10:06
• Updated: 31/Mar/19 02:49
• Resolved: 14/Sep/18 03:16

Description

When we want to count a column(with same NULL value), there is different result from kylin and hive SQL. Is there a way to exclude NULL value in count measure calculation for a particular column?
Here is the example:

1. Here is source data:
Date ID
2017-10-10 dfe343ddfe3f5
2017-10-11 fer234d656dff
2017-10-11 NULL
2017-10-12 jui6jnc3ncce3

2. run SQL in Hive:
select Date, count, count(ID) from table group by Date;
2017-10-10 1 1
2017-10-11 2 1
2017-10-12 1 1

3. run same SQL in Kylin:
select Date, count, count(ID) from table group by Date;
2017-10-10 1 1
2017-10-11 2 2
2017-10-12 1 1

Issue Links

• duplicates: KYLIN-3359 Support sum(expression) if possible
• duplicates: KYLIN-3883 Kylin supports column count aggregation