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Posted to dev@hive.apache.org by "Amareshwari Sriramadasu (JIRA)" <ji...@apache.org> on 2010/08/10 09:22:17 UTC
[jira] Commented: (HIVE-741) NULL is not handled correctly in join
[ https://issues.apache.org/jira/browse/HIVE-741?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12896789#action_12896789 ]
Amareshwari Sriramadasu commented on HIVE-741:
----------------------------------------------
bq. When 'null' is replaced by '' it works.
I see the same result even if 'null' is replaced with ''.
To reproduce the above, I created a table input1 with
{code}
hive> create table input1 (key int, value int);
{code}
Loaded the following input using Load data command
{noformat}
in.txt
^A35
12^A
10^A1000
10^A100
100^A100
{noformat}
I see the following output for join queries executed.
{noformat}
hive> select * from input1 a join input1 b on a.key=b.value;
Output:
NULL 35 12 NULL
100 100 10 100
100 100 100 100
Expected Output:
100 100 10 100
100 100 100 100
hive> select * from input1 a left outer join input1 b on a.key=b.value;
OUTPUT:
NULL 35 12 NULL
10 1000 NULL NULL
10 100 NULL NULL
12 NULL NULL NULL
100 100 10 100
100 100 100 100
Expected Output:
NULL 35 NULL NULL
10 1000 NULL NULL
10 100 NULL NULL
12 NULL NULL NULL
100 100 10 100
100 100 100 100
hive> select * from input1 a right outer join input1 b on a.key=b.value;
OUTPUT:
NULL 35 12 NULL
NULL NULL NULL 35
100 100 10 100
100 100 100 100
NULL NULL 10 1000
ExpectedOutput:
NULL NULL NULL 35
NULL NULL 12 NULL
100 100 10 100
100 100 100 100
NULL NULL 10 1000
{noformat}
Expected output is obtained from mysql db for a similar query.
Ning, if you are not working on the fix for this, I would like to contribute. Would need your help understanding join code also, as I'm a new to hive.
> NULL is not handled correctly in join
> -------------------------------------
>
> Key: HIVE-741
> URL: https://issues.apache.org/jira/browse/HIVE-741
> Project: Hadoop Hive
> Issue Type: Bug
> Reporter: Ning Zhang
> Assignee: Ning Zhang
>
> With the following data in table input4_cb:
> Key Value
> ------ --------
> NULL 325
> 18 NULL
> The following query:
> {code}
> select * from input4_cb a join input4_cb b on a.key = b.value;
> {code}
> returns the following result:
> NULL 325 18 NULL
> The correct result should be empty set.
> When 'null' is replaced by '' it works.
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