hadoop-common-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Doug Cutting (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-689) hadoop should provide a common way to wrap instances with different types into one type
Date Fri, 10 Nov 2006 19:22:38 GMT
    [ http://issues.apache.org/jira/browse/HADOOP-689?page=comments#action_12448829 ] 
            
Doug Cutting commented on HADOOP-689:
-------------------------------------

Overall this looks good.  A few issues.

1. A new array of classes should not be allocated for each call to readFields().  Perhaps
instead introspection should be used to call a static getTypes() method and somehow cache
this per subclass.  At the least, the example code should create the array as a static field,
and then have the getTypes() implementation return a reference to this.

2. set(), get(), and getTypes() need javadoc.


> 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.

-- 
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira

        

Mime
View raw message