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https://issues.apache.org/jira/browse/HIVE-1642?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12931705#action_12931705
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Liyin Tang commented on HIVE-1642:
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In the case: A left outer join B right outer join C, A must be small table.
I have a test case: auto_join25.q to test the backup test. There are several
query in this test case.
The idea is just set the hive.hashtable.max.memory.usage = 0.00001. It means
if the local task uses more than 0.00001% of memory, it will abort. Obviously,
all local tasks will always fail in this task case. So the back up will run
after the local task failed.
> Convert join queries to map-join based on size of table/row
> -----------------------------------------------------------
>
> Key: HIVE-1642
> URL: https://issues.apache.org/jira/browse/HIVE-1642
> Project: Hive
> Issue Type: Improvement
> Components: Query Processor
> Reporter: Namit Jain
> Assignee: Liyin Tang
> Fix For: 0.7.0
>
> Attachments: hive_1642_1.patch
>
>
> Based on the number of rows and size of each table, Hive should automatically
> be able to convert a join into map-join.
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