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https://issues.apache.org/jira/browse/HIVE-4506?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Fern updated HIVE-4506:
-----------------------
Priority: Minor (was: Major)
Description:
I know we can use map side join for small table.
by my test, if I use HQL like this
------
select /*+mapjoin(b,c)*/...
from a
left join b
on ...
left join c
on ...
-------
b and c are both small tables, I expect do the join in one map reduce using map
side join. Actually, it would generate two map-reduce by sequence.
Sorry, currently I am just a user of hive and not dig into the code, so I this
is what I expect and have no idea about how to improve.
Affects Version/s: 0.10.0
Summary: use one map reduce to join multiple small tables (was:
join multi small tables )
> use one map reduce to join multiple small tables
> -------------------------------------------------
>
> Key: HIVE-4506
> URL: https://issues.apache.org/jira/browse/HIVE-4506
> Project: Hive
> Issue Type: Wish
> Affects Versions: 0.10.0
> Reporter: Fern
> Priority: Minor
>
> I know we can use map side join for small table.
> by my test, if I use HQL like this
> ------
> select /*+mapjoin(b,c)*/...
> from a
> left join b
> on ...
> left join c
> on ...
> -------
> b and c are both small tables, I expect do the join in one map reduce using
> map side join. Actually, it would generate two map-reduce by sequence.
> Sorry, currently I am just a user of hive and not dig into the code, so I
> this is what I expect and have no idea about how to improve.
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