Harish Butani created HIVE-8558:
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Summary: CBO: enable n-way joins after CBO join reordering
Key: HIVE-8558
URL: https://issues.apache.org/jira/browse/HIVE-8558
Project: Hive
Issue Type: Bug
Reporter: Harish Butani
Assignee: Harish Butani
With CBO, we disable n-way joins. But for consecutive tables we can safely
collapse into n-way joins. For e.g this is safe to collapse:
{code}
select p1.p_name, p2.p_name, p3.p_name from part p1 join part p2 on p1.p_name =
p2.p_name join part p3 on p3.p_name = p1.p_name;
{code}
whereas, we shouldn't reorder in this case:
{code}
select p1.p_name, p2.p_name, p3.p_name
from part p1 join part p2 on p1.p_name = p2.p_name join part p3 on p3.p_size =
p1.p_size and p3.p_size = p2.p_size join part p4 on p1.p_name = p4.p_name;
{code}
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