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From "Shinichi Yamashita (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (SQOOP-387) Use TRUNCATE for PostgreSQLManager
Date Mon, 07 Nov 2011 18:52:51 GMT

    [ https://issues.apache.org/jira/browse/SQOOP-387?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13145700#comment-13145700
] 

Shinichi Yamashita commented on SQOOP-387:
------------------------------------------

The reason that overridden only PostgreSQLManager (not SqlManager) is because PostgreSQL can
handle truncate in transaction. 
In other words TRUNCATE of PostgreSQL can have rollback mechanism. 

In addition, PostgreSQL doesn't release disk space until it executes "VACUUM". 
Therefore the implementation of current PostgreSQL causes performance degradation in the long
term.

                
> Use TRUNCATE for PostgreSQLManager
> ----------------------------------
>
>                 Key: SQOOP-387
>                 URL: https://issues.apache.org/jira/browse/SQOOP-387
>             Project: Sqoop
>          Issue Type: Improvement
>          Components: connectors/postgresql
>            Reporter: Shinichi Yamashita
>         Attachments: SQOOP-387.patch
>
>
> PostgreSQLManager uses "DELETE" sentence for procesing in staging-table.
> When it does "EXPORT" many times, the processing time is prolonged in "DELETE".
> Therefore replace it with "TRUNCATE" sentence and improve performance.

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