The result of left semi join is not correct
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Key: HIVE-1723
URL: https://issues.apache.org/jira/browse/HIVE-1723
Project: Hadoop Hive
Issue Type: Bug
Reporter: 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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