Navis created HIVE-3464:
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Summary: Merging join tree may reorder joins which could be invalid
Key: HIVE-3464
URL: https://issues.apache.org/jira/browse/HIVE-3464
Project: Hive
Issue Type: Bug
Components: Query Processor
Affects Versions: 0.10.0
Reporter: Navis
Assignee: Navis
Currently, hive merges join tree from right to left regardless of join types,
which may introduce join reordering. For example,
select * from a join a b on a.key=b.key join a c on b.key=c.key join a d on
a.key=d.key;
Hive tries to merge join tree in a-d=b-d, a-d=a-b, b-c=a-b order and a-d=a-b
and b-c=a-b will be merged. Final join tree is "a-(bdc)".
With this, ab-d join will be executed prior to ab-c. But if join type of -c and
-d is different, this is not valid.
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