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https://issues.apache.org/jira/browse/HIVE-2120?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
He Yongqiang updated HIVE-2120:
-------------------------------
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.
Assignee: He Yongqiang
Summary: auto convert map join may miss good candidates (was: auto
convert map join does not work with queries that have a subquery alias)
> auto convert map join may miss good candidates
> ----------------------------------------------
>
> Key: HIVE-2120
> URL: https://issues.apache.org/jira/browse/HIVE-2120
> Project: Hive
> Issue Type: Bug
> Reporter: He Yongqiang
> Assignee: He Yongqiang
> Attachments: HIVE-2120.1.patch
>
>
> 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.
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