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Hadoop >> mail # user >> decompressing bzip2 data with a custom InputFormat


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Re: decompressing bzip2 data with a custom InputFormat
Yes you have to deal with the compression. Usually, you'll load the
compression codec in your RecordReader. You can see an example of how
TextInputFormat's LineRecordReader does it:

https://github.com/apache/hadoop-common/blob/release-1.0.1/src/mapred/org/apache/hadoop/mapreduce/lib/input/LineRecordReader.java

-Joey

On Wed, Mar 14, 2012 at 11:08 AM, Tony Burton <[EMAIL PROTECTED]> wrote:
> Hi - sorry to bump this, but I'm having trouble resolving this.
>
> Essentially the question is: If I create my own InputFormat by subclassing TextInputFormat, does the subclass have to handle its own streaming of compressed data? If so, can anyone point me at an example where this is done?
>
> Thanks!
>
> Tony
>
>
>
>
>
>
>
> -----Original Message-----
> From: Tony Burton [mailto:[EMAIL PROTECTED]]
> Sent: 12 March 2012 18:05
> To: [EMAIL PROTECTED]
> Subject: decompressing bzip2 data with a custom InputFormat
>
>  Hi,
>
> I'm setting up a map-only job that reads large bzip2-compressed data files, parses the XML and writes out the same data in plain text format. My XML InputFormat extends TextInputFormat and has a RecordReader based upon the one you can see at http://xmlandhadoop.blogspot.com/ (my version of it works great for uncompressed XML input data). For compressed data, I've added io.compression.codecs to my core-site.xml and set it to o.a.h.io.compress.BZip2Codec. I'm using Hadoop 0.20.2.
>
> Have I forgotten something basic when running a Hadoop job to read compressed data? Or, given that I've written my own InputFormat, should I be using an InputStream that can carry out the decompression itself?
>
> Thanks
>
> Tony
>
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Joseph Echeverria
Cloudera, Inc.
443.305.9434