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https://issues.apache.org/jira/browse/HADOOP-7076?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13165911#comment-13165911
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Luke Lu commented on HADOOP-7076:
---------------------------------
The code especially the docs/comments looks good to me. I wonder if the name of
the codec would better be called SkipGzipCodec instead of SplittableGzipCodec
mostly because the latter would be a good name for a real splittable variant of
gzip format and that the former sounds weird enough to prompt user to read the
documentation to find out that the codec actually do O(s*n) io, which is mostly
suitable for processing archived gzipped files infrequently with number of
splits less than the compression factor (uncompressed size/compressed size)
(not a precise criterion BTW). Otherwise, you'd better off convert these files
into a real splittable compressed format.
> Splittable Gzip
> ---------------
>
> Key: HADOOP-7076
> URL: https://issues.apache.org/jira/browse/HADOOP-7076
> Project: Hadoop Common
> Issue Type: New Feature
> Components: io
> Reporter: Niels Basjes
> Assignee: Niels Basjes
> Attachments: HADOOP-7076-2011-01-26.patch,
> HADOOP-7076-2011-01-29.patch, HADOOP-7076-2011-02-05.patch,
> HADOOP-7076-2011-02-06.patch, HADOOP-7076-2011-05-18.patch,
> HADOOP-7076-2011-08-05-2255.patch, HADOOP-7076-2011-08-05-2315.patch,
> HADOOP-7076-2011-12-04-2332.patch, HADOOP-7076-branch-0.22.patch,
> HADOOP-7076.patch
>
>
> Files compressed with the gzip codec are not splittable due to the nature of
> the codec.
> This limits the options you have scaling out when reading large gzipped input
> files.
> Given the fact that gunzipping a 1GiB file usually takes only 2 minutes I
> figured that for some use cases wasting some resources may result in a
> shorter job time under certain conditions.
> So reading the entire input file from the start for each split (wasting
> resources!!) may lead to additional scalability.
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