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From "Owen O'Malley (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-4065) support for reading binary data from flat files
Date Tue, 09 Sep 2008 23:13:44 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-4065?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12629652#action_12629652
] 

Owen O'Malley commented on HADOOP-4065:
---------------------------------------

I think this is too complicated. What is the justification for these new interfaces? We already
have RecordReader that already 
expresses these concepts.

Once the TFile stuff is ready, I think it would make a lot of sense to build an ObjectFile
that uses the pluggable serializer
framework to save any objects. At that point, it becomes a potential replacement for SequenceFile.
By using the serializer
framework, it should work fine with Java serialization, Thrift, or Protocol Buffers. I don't
think having a Thrift file format is very
compelling at that point.

> 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
>         Attachments: HADOOP-4065.0.txt, ThriftFlatFile.java
>
>
> 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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