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From Owen O'Malley <o...@yahoo-inc.com>
Subject Re: [jira] Commented: (HADOOP-433) Better access to the RecordReader
Date Wed, 09 Aug 2006 21:46:08 GMT

On Aug 9, 2006, at 12:21 PM, Eric Baldeschwieler wrote:

> Why not provide a pointer to the real record reader?  Seems like a  
> valid OO way to get access to all kinds of things.

Those attributes were put in to the JobConf so that Hadoop could re- 
run an isolated task, so they had to be serializable. Putting real  
objects into the JobConf breaks that property.

Ben hasn't explained why he wants the RecordReader, so I was trying  
to guess. The problem with giving out references to the RecordReader  
is that you are exposing the framework's implementation details. In  
particular, all you can really do to a record reader is advance it.  
That really isn't something that the Mapper should be doing.

-- Owen

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