[jira] Reopened: (HADOOP-3646) Providing bzip2 as codec

["Chris Douglas (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HADOOP-3646?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Chris Douglas reopened HADOOP-3646:
-----------------------------------


> Providing bzip2 as codec
> ------------------------
>
>                 Key: HADOOP-3646
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3646
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: conf, io
>    Affects Versions: 0.19.0
>            Reporter: Abdul Qadeer
>             Fix For: 0.19.0
>
>         Attachments: HADOOP-3646.patch, HADOOP-3646.patch
>
>   Original Estimate: 1008h
>  Remaining Estimate: 1008h
>
> Hadoop recognizes gzip compressed input and automatically decompresses the data before providing it to the mapper. But Hadoop can not split a gzip stream due to the very nature of the gzip compression. Consequently one gzip stream (e.g a whole file) can go to only one mapper.  On the contrary Bzip2 compressed stream can be split across its block delimiters.
> We are interested in extending Hadoop to support splittable bzip2 with a codec.  (https://issues.apache.org/jira/browse/HADOOP-1823  uses input reader to split the bzip2 files, which must be provided by the user and can handle FileInputFormat.  If a user wants to use some other input format or wants to do custom record handling, he must write a new input reader!)
> We have a patch now that provides a basic bzip2 codec equivalent to the current gzip codec.  We are in the process of extending that to support splitting.

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