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From "Xabriel J Collazo Mojica (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-11644) Contribute CMX compression
Date Mon, 29 Jun 2015 18:07:05 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-11644?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14606021#comment-14606021
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Xabriel J Collazo Mojica commented on HADOOP-11644:
---------------------------------------------------

It would be great if someone could review the patch. Let me know if you have questions.

> Contribute CMX compression
> --------------------------
>
>                 Key: HADOOP-11644
>                 URL: https://issues.apache.org/jira/browse/HADOOP-11644
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: io
>            Reporter: Xabriel J Collazo Mojica
>            Assignee: Xabriel J Collazo Mojica
>         Attachments: HADOOP-11644.001.patch
>
>   Original Estimate: 336h
>  Remaining Estimate: 336h
>
> Hadoop natively supports four main compression algorithms: BZIP2, LZ4, Snappy and ZLIB.
> Each one of these algorithms fills a gap:
> bzip2 : Very high compression ratio, splittable
> LZ4 : Very fast, non splittable
> Snappy : Very fast, non splittable
> zLib : good balance of compression and speed.
> We think there is a gap for a compression algorithm that can perform fast compress and
decompress, while also being splittable. This can help significantly on jobs where the input
file sizes are >= 1GB.
> For this, IBM has developed CMX. CMX is a dictionary-based, block-oriented, splittable,
concatenable compression algorithm developed specifically for Hadoop workloads. Many of our
customers use CMX, and we would love to be able to contribute it to hadoop-common. 
> CMX is block oriented : We typically use 64k blocks. Blocks are independently decompressable.
> CMX is splittable : We implement the SplittableCompressionCodec interface. All CMX files
are a multiple of 64k, so the splittability is achieved in a simple way with no need for external
indexes.
> CMX is concatenable : Two independent CMX files can be concatenated together. We have
seen that some projects like Apache Flume require this feature.



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