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From "Doug Cutting (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-689) hadoop should provide a common way to wrap instances with different types into one type
Date Fri, 10 Nov 2006 19:22:40 GMT
     [ http://issues.apache.org/jira/browse/HADOOP-689?page=all ]

Doug Cutting updated HADOOP-689:
--------------------------------

    Status: Open  (was: Patch Available)

> hadoop should provide a common way to wrap instances with different types into one type
> ---------------------------------------------------------------------------------------
>
>                 Key: HADOOP-689
>                 URL: http://issues.apache.org/jira/browse/HADOOP-689
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: io
>         Environment: All environment
>            Reporter: Feng Jiang
>         Attachments: HADOOP-689.patch
>
>
> When two sequence files, which have same Key type but different Value types, are mapped
out to reduce, multiple Value types is not allowed. In this case, we need a way to wrap instances
with different types into one class type to reduce.
> In current code, ObjectWritable is a sole choice. but it costs too many space, because
the class declaration will be appended into output file as a string for every Key-value pair.

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