Shobika Selvaraj created HIVE-27324:
---------------------------------------
Summary: Hive query with NOT IN condition is giving incorrect
results when the sub query table contains the null value.
Key: HIVE-27324
URL: https://issues.apache.org/jira/browse/HIVE-27324
Project: Hive
Issue Type: Bug
Components: Hive
Affects Versions: 3.1.0, All Versions
Reporter: Shobika Selvaraj
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
productINFO : 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.
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