[HIVE-27324] Hive query with NOT IN condition is giving incorrect results when the sub query table contains the null value.

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.1.3
• Fix Version/s: 4.0.0
• Component/s: Hive
• Labels: pull-request-available
• Assignee: Diksha
• Reporter: Shobika Selvaraj
• Created: 06/May/23 05:57
• Updated: 29/Mar/24 17:49
• Resolved: 03/Nov/23 15:39

Description

Hive query giving empty results when the sub query table contains the null value. 

We encountered two issues here. 

1) The query - "select * from t3 where age not in (select distinct(age) age from t1);" is giving empty results when the table t1 contains a null value. Disabling cbo didn't helped here.

2) Let's consider the table t3 has null value and table t1 doesn't have any null values. Now if we run the above query it is returning other data's but not the null value from t3. If we disable the cbo then it's giving result with null value. 

 

REPRO STEPS WITH DETAILED EXPLANATION AS BELOW:

FIRST ISSUE:
Create two tables and insert data with null values as below:
-------
create table t3 (id int,name string, age int);

 
insert into t3 values(1,'Sagar',23),(2,'Sultan',NULL),(3,'Surya',23),(4,'Raman',45),(5,'Scott',23),(6,'Ramya',5),(7,'',23),(8,'',23),(9,'ron',3),(10,'Sam',22),(11,'nick',19),(12,'fed',18),(13,'kong',13),(14,'hela',45);
 
create table t1 (id int,name string, age int);

insert into t1 values(1,'Sagar',23),(2,'Sultan',NULL),(3,'Surya',23),(4,'Raman',45),(5,'Scott',23),(6,'Ramya',5),(7,'',23),(8,'',23);
-------
 
Then executed the below query: 
------
select * from t3
where age not in (select distinct(age) age from t1);
------
 
The result should be as below:

+--------+----------+---------+
| t3.id  | t3.name  | t3.age  |
+--------+----------+---------+
| 9      | ron      | 3       |
| 10     | Sam      | 22      |
| 11     | nick     | 19      |
| 12     | fed      | 18      |
| 13     | kong     | 13      |
+--------+----------+---------+
5 rows selected (35.897 seconds) 

But when we run the above query it is giving zero records:

0: jdbc:hive2://zk0-shobia.lhlexkfu3vfebcezzj> select * from t3
. . . . . . . . . . . . . . . . . . . . . . .> where age not in (select distinct(age) age from t1);
INFO  : Compiling command(queryId=hive_20230427164202_e25b671a-f3bd-41e4-b364-844466305d96): select * from t3
where age not in (select distinct(age) age from t1)
INFO  : Warning: Map Join MAPJOIN[37][bigTable=?] in task 'Map 1' is a cross product
......
.....
INFO  : Completed executing command(queryId=hive_20230427164202_e25b671a-f3bd-41e4-b364-844466305d96); Time taken: 10.191 seconds
INFO  : OK
+--------+----------+---------+
| t3.id  | t3.name  | t3.age  |
+--------+----------+---------+
+--------+----------+---------+
No rows selected (12.17 seconds) 

The query works fine when we use nvl function or not null condition. 
 
So as a workaround we can use nvl function for both main and sub query as below:

select * from t3 where nvl(age,'-') not in (select distinct(nvl(age,'-')) age from t1); 

 
SECOND ISSUE: 

Also while testing multiple scenario's i found one more issue as well.

When the sub query table (t1) doesn't contain any null values then the query is giving result but it is ignoring the null values of the main table(t3) .
 
For example: Created another table t4 and inserted the data's without any null values:

create table t4 (id int,name string, age int);
insert into t4 values(1,'Sagar',23),(3,'Surya',23),(4,'Raman',45),(5,'Scott',23),(6,'Ramya',5),(7,'',23),(8,'',23);

Now i tested with the below query and it gives 5 records. The count should be six and it omitted the null value of the table t3:

0: jdbc:hive2://zk0-shobia.lhlexkfu3vfebcezzj> select * from t3
. . . . . . . . . . . . . . . . . . . . . . .> where age not in (select distinct(age) age from t4);
INFO  : Compiling command(queryId=hive_20230427164745_f20f47ce-614d-493d-8910-99a118de089c): select * from t3
where age not in (select distinct(age) age from t4)
INFO  : Warning: Map Join MAPJOIN[37][bigTable=?] in task 'Map 1' is a cross product
......
......
INFO  : Completed executing command(queryId=hive_20230427164745_f20f47ce-614d-493d-8910-99a118de089c); Time taken: 17.724 seconds
INFO  : OK
+--------+----------+---------+
| t3.id  | t3.name  | t3.age  |
+--------+----------+---------+
| 9      | ron      | 3       |
| 10     | Sam      | 22      |
| 11     | nick     | 19      |
| 12     | fed      | 18      |
| 13     | kong     | 13      |
+--------+----------+---------+
5 rows selected (19.674 seconds) 

But disabling CBO fixed this issue:

0: jdbc:hive2://zk0-shobia.lhlexkfu3vfebcezzj> set hive.cbo.enable=false;
No rows affected (0.02 seconds)
0: jdbc:hive2://zk0-shobia.lhlexkfu3vfebcezzj> select * from t3
. . . . . . . . . . . . . . . . . . . . . . .> where age not in (select distinct(age) age from t4);
INFO  : Compiling command(queryId=hive_20230427165029_6c3167b0-c706-4230-a32f-2e4bc528be8f): select * from t3
where age not in (select distinct(age) age from t4)
INFO  : Warning: Map Join MAPJOIN[41][bigTable=t3] in task 'Map 1' is a cross product
INFO  : Semantic Analysis Completed (retrial = false)
.......
.......
INFO  : Completed executing command(queryId=hive_20230427165029_6c3167b0-c706-4230-a32f-2e4bc528be8f); Time taken: 13.738 seconds
INFO  : OK
+--------+----------+---------+
| t3.id  | t3.name  | t3.age  |
+--------+----------+---------+
| 2      | Sultan   | NULL    |
| 9      | ron      | 3       |
| 10     | Sam      | 22      |
| 11     | nick     | 19      |
| 12     | fed      | 18      |
| 13     | kong     | 13      |
+--------+----------+---------+
6 rows selected (14.526 seconds) 

I am not sure this how hive works or not by omitting the null values. Even if it omits the null values then it should give the other records(FOR ISSUE 1) for the sub query table which contains null values.

Issue Links

• incorporates: HIVE-27844 Multi destination queries giving error for Not in operators
• links to: GitHub Pull Request #4636