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From "Mahadev konar (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-4065) support for reading binary data from flat files
Date Mon, 08 Sep 2008 22:23:44 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-4065?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12629315#action_12629315
] 

Mahadev konar commented on HADOOP-4065:
---------------------------------------

the tfilerecordreader would just return raw bytes for keys and values and its up to the application
to convert the raw bytes to types. Though as far as our implementation goes right now -- we
dont have a map reduce interface for Tfiles. We intend to provide one.

The TFile is also supposed to be readable/writable in  other languages with the spec being
clear enough on how to read and write Tfiles. We intend to provide just java implementation
of Tfiles though. 

> support for reading binary data from flat files
> -----------------------------------------------
>
>                 Key: HADOOP-4065
>                 URL: https://issues.apache.org/jira/browse/HADOOP-4065
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>            Reporter: Joydeep Sen Sarma
>
> like textinputformat - looking for a concrete implementation to read binary records from
a flat file (that may be compressed).
> it's assumed that hadoop can't split such a file. so the inputformat can set splittable
to false.
> tricky aspects are:
> - how to know what class the file contains (has to be in a configuration somewhere).
> - how to determine EOF (would be nice if hadoop can determine EOF and not have the deserializer
throw an exception  (which is hard to distinguish from a exception due to corruptions?)).
this is easy for non-compressed streams - for compressed streams - DecompressorStream has
a useful looking getAvailable() call - except the class is marked package private.

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