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https://issues.apache.org/jira/browse/HADOOP-12041?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15088720#comment-15088720
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Kai Zheng commented on HADOOP-12041:
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Hi [~zhz],
bq. we should rename the existing coder as {{RSRawEncoderLegacy}} and name the
new one as RSRawEncoder
I'm afraid we'd better do the rename things separately. If we do it here, then
the patch is rather messy and hard to review. In the current patch revision,
most of the codes are new and no change for existing coders. But doing the
rename, like RSRawEncoder->RSRawEncoderLegacy, RSRawEncoder2->RSRawEncoder will
make the patch be like most of changes into the existing RS coders.
So how about we do this separately, together some other things like applying it
to HDFS side?
> Implement another Reed-Solomon coder in pure Java
> -------------------------------------------------
>
> Key: HADOOP-12041
> URL: https://issues.apache.org/jira/browse/HADOOP-12041
> Project: Hadoop Common
> Issue Type: Sub-task
> Reporter: Kai Zheng
> Assignee: Kai Zheng
> Attachments: HADOOP-12041-v1.patch, HADOOP-12041-v2.patch,
> HADOOP-12041-v3.patch, HADOOP-12041-v4.patch, HADOOP-12041-v5.patch
>
>
> Currently existing Java RS coders based on {{GaloisField}} implementation
> have some drawbacks or limitations:
> * The decoder computes not really erased units unnecessarily (HADOOP-11871);
> * The decoder requires parity units + data units order for the inputs in the
> decode API (HADOOP-12040);
> * Need to support or align with native erasure coders regarding concrete
> coding algorithms and matrix, so Java coders and native coders can be easily
> swapped in/out and transparent to HDFS (HADOOP-12010);
> * It's unnecessarily flexible but incurs some overhead, as HDFS erasure
> coding is totally a byte based data system, we don't need to consider other
> symbol size instead of 256.
> This desires to implement another RS coder in pure Java, in addition to the
> existing {{GaliosField}} from HDFS-RAID. The new Java RS coder will be
> favored and used by default to resolve the related issues. The old HDFS-RAID
> originated coder will still be there for comparing, and converting old data
> from HDFS-RAID systems.
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