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From "Siying Dong (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-2201) reduce name node calls in hive by creating temporary directories
Date Fri, 10 Jun 2011 07:38:59 GMT

     [ https://issues.apache.org/jira/browse/HIVE-2201?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Siying Dong updated HIVE-2201:
------------------------------

    Status: Patch Available  (was: In Progress)

> reduce name node calls in hive by creating temporary directories
> ----------------------------------------------------------------
>
>                 Key: HIVE-2201
>                 URL: https://issues.apache.org/jira/browse/HIVE-2201
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Namit Jain
>            Assignee: Siying Dong
>         Attachments: HIVE-2201.1.patch
>
>
> Currently, in Hive, when a file gets written by a FileSinkOperator,
> the sequence of operations is as follows:
> 1. In tmp directory tmp1, create a tmp file _tmp_1
> 2. At the end of the operator, move
> /tmp1/_tmp_1 to /tmp1/1
> 3. Move directory /tmp1 to /tmp2
> 4. For all files in /tmp2, remove all files starting with _tmp and
> duplicate files.
> Due to speculative execution, a lot of temporary files are created
> in /tmp1 (or /tmp2). This leads to a lot of name node calls,
> specially for large queries.
> The protocol above can be modified slightly:
> 1. In tmp directory tmp1, create a tmp file _tmp_1
> 2. At the end of the operator, move
> /tmp1/_tmp_1 to /tmp2/1
> 3. Move directory /tmp2 to /tmp3
> 4. For all files in /tmp3, remove all duplicate files.
> This should reduce the number of tmp files.

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