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From "Ning Zhang (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HIVE-963) no out of memory errors for skewed join
Date Wed, 23 Dec 2009 21:56:29 GMT

     [ https://issues.apache.org/jira/browse/HIVE-963?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Ning Zhang updated HIVE-963:
----------------------------

    Attachment: HIVE-963_2.patch

Uploading a new patch. Changes include:

 1) change ArrayListWrapper to RowContainer.
 2) In RowContainer, the input shoudl always be a list of object, which should be come with
a SerDe and ObjectInspector to spill out to disk.
 3) added in the joinDesc to indicate the tableDesc of the inputs to the join operator.
 4) added a union test join40.q to test the case when the block size is 1 where spill will
actually happen. 


> no out of memory errors for skewed join
> ---------------------------------------
>
>                 Key: HIVE-963
>                 URL: https://issues.apache.org/jira/browse/HIVE-963
>             Project: Hadoop Hive
>          Issue Type: Improvement
>          Components: Query Processor
>            Reporter: Namit Jain
>            Assignee: Ning Zhang
>         Attachments: HIVE-963.patch, HIVE-963_2.patch
>
>
> Currently, in case of skew, hive runs out of memory.
> A simpler fix would be to use JDBM to store data and use that.
> It can be configurable and JDBM should only be triggered if the number of values for
a given key exceed a given number.

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