Details
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Bug
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Status: Closed
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Major
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Resolution: Fixed
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None
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None
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Reviewed
Description
In case in a join, there is a subquery which does a simple select, the auto convert map join may miss a good candidate at run time. The plan generated is correct, but the selection at runtime has a bug.
For example:
set hive.smalltable.filesize=1000;
create table src_one as select * from src where key=100;
select count(1)
from
(
select * from src
) subq
join
src_small on src.key = subq.key;
The table src_small can be a small table. This is in the plan, but at runtime it gets filtered out.