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Subject: Re: Memory problems with BytesWritable and huge binary files
From: Vinod Kumar Vavilapalli <vinodkv@hortonworks.com>
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Date: Fri, 24 Jan 2014 14:42:45 -0800
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Okay. Assuming you don't need a whole file (video) in memory for your processing, you can simply write a Inputformat/RecordReader implementation that streams through any given file and processes it.

+Vinod

On Jan 24, 2014, at 12:44 PM, Adam Retter <adam.retter@googlemail.com> wrote:

>> Is your data in any given file a bunch of key-value pairs?
> 
> No. The content of each file itself is the value we are interested in,
> and I guess that it's filename is the key.
> 
>> If that isn't the
>> case, I'm wondering how writing a single large key-value into a sequence
>> file helps. It won't. May be you can give an example of your input data?
> 
> Well from the Hadoop O'Reilly book, I rather got the impression that
> HDFS does not like small files due to it's 64MB block size, and it is
> instead recommended to place small files into a Sequence file. Is that
> not the case?
> 
> Our input data really varies between 130 different file types, it
> could be Microsoft Office documents, Video Recordings, Audio, CAD
> diagrams etc.
> 
>> If indeed they are a bunch of smaller sized key-value pairs, you can write
>> your own custom InputFormat that reads the data from your input files one
>> k-v pair after another, and feed it to your MR job. There isn't any need for
>> converting them to sequence-files at that point.
> 
> As I mentioned in my initial email, each file cannot be split up!
> 
>> Thanks
>> +Vinod
>> Hortonworks Inc.
>> http://hortonworks.com/
>> 
>> 
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> 
> -- 
> Adam Retter
> 
> skype: adam.retter
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> http://www.adamretter.org.uk


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