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https://issues.apache.org/jira/browse/HIVE-1723?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12922231#action_12922231
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Namit Jain commented on HIVE-1723:
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Can you add a test for the same ?
Set hive.mapjoin.cache.numrows to a lower number, it is set to 25000 currently.
> The result of left semi join is not correct
> -------------------------------------------
>
> Key: HIVE-1723
> URL: https://issues.apache.org/jira/browse/HIVE-1723
> Project: Hadoop Hive
> Issue Type: Bug
> Reporter: Liyin Tang
> Assignee: Liyin Tang
>
> In the test case semijoin.q, there is a query:
> select /*+ mapjoin(b) */ a.key from t3 a left semi join t1 b on a.key = b.key
> sort by a.key;
> I think this query will return a wrong result if table t1 is larger than
> 25000 different keys
> To be simple, I tried a very similar query:
> select /*+ mapjoin(b) */ a.key from test_semijoin a left semi join
> test_semijoin b on a.key = b.key sort by a.key;
> The table of test_semijoin is like
> 0 0
> 1 1
> 2 2
> 3 3
> 4 4
> 5 5
> ... ...
> ... ....
> 25000 25000
> 25001 25001
> ... ....
> ... ....
> 25999 25999
> 26000 26000
> So we can easily estimate the correct result of this query should be the same
> keys from table test_semijoin itsel.
> Actually, the result is only part of that: only from 0 to 24544.
> 0
> 1
> 2
> ..
> ..
> 24543
> 24544
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