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From "Tomoya Tainaka (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (MAPREDUCE-2453) DBinputFormat throws OutOfMemory exceptions when importing large tables from PostgreSQL.
Date Tue, 26 Apr 2011 02:11:03 GMT

     [ https://issues.apache.org/jira/browse/MAPREDUCE-2453?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Tomoya Tainaka updated MAPREDUCE-2453:
--------------------------------------

    Attachment:     (was: MAPREDUCE-2453-3.patch)

> DBinputFormat throws OutOfMemory exceptions when importing large tables from PostgreSQL.
> ----------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-2453
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2453
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>    Affects Versions: 0.21.0
>            Reporter: Tomoya Tainaka
>            Priority: Minor
>
> DBinputFormat throws OutOfMemory exceptions and Java heap space errors when importing
large tables from PostgreSQL. This is because loading the whole resultset into memory at the
same time. As a consequence, the Java heap space is exhausted.
> Also, this problem happens with DataDrivenDBInputFormat.
> I suggest utilizing "Fetch Size" parameter of JDBC within DBInputFormat. 
> I made patches as follows:
> ・modifying org.apache.hadoop.mapreduce.lib.db.DBInputFormat. 
> ・creating org.apache.hadoop.mapreduce.PostgreSQLDBRecordReader.java. 
> ・adding JDBC options of fetch size, which are setFetchSize() and setAutoCommit().
> I also modified DataDrivenDBinputFormat in the same way as DBInputFormat.

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