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From "Ravi Prakash (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-8065) distcp should have an option to compress data while copying.
Date Fri, 18 Nov 2016 00:47:03 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-8065?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15675308#comment-15675308
] 

Ravi Prakash commented on HADOOP-8065:
--------------------------------------

Hi Yongjun!

Thanks for rebasing the patch and your polishing touches. I think HADOOP-13114 might be the
more appropriate JIRA for these changes (which Suraj kindly filed at my request earlier.)
since this patch does not compress *during* transfer; only after transfer and before writing
to HDFS.
- {{getCompressionCodcec}} has the same typo I pointed out to Suraj. He did post updated patches
on HADOOP-13114. I apologize for neglecting to review those patches despite Suraj's requests.
- {{getCompressionCodcec}} also uses ReflectionUtils. I don't know if it'd be better to use
[this pattern|https://github.com/apache/hadoop/blob/b4f1971ff1dd578353036d7a123fe83c27c1e803/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/lib/CombineFileInputFormat.java#L159]
instead?
- We're still not using a CodecPool like I suggested earlier. The patch in HADOOP-13114 actually
is. Let me rebase and upload that. Could you please take a look at that?

> distcp should have an option to compress data while copying.
> ------------------------------------------------------------
>
>                 Key: HADOOP-8065
>                 URL: https://issues.apache.org/jira/browse/HADOOP-8065
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: fs
>    Affects Versions: 0.20.2
>            Reporter: Suresh Antony
>            Assignee: Suraj Nayak
>            Priority: Minor
>              Labels: distcp
>             Fix For: 0.20.2
>
>         Attachments: HADOOP-8065-trunk_2015-11-03.patch, HADOOP-8065-trunk_2015-11-04.patch,
HADOOP-8065-trunk_2016-04-29-4.patch, HADOOP-8065.005.patch, HADOOP-8065.006.patch, patch.distcp.2012-02-10
>
>
> We would like compress the data while transferring from our source system to target system.
One way to do this is to write a map/reduce job to compress that after/before being transferred.
This looks inefficient. 
> Since distcp already reading writing data it would be better if it can accomplish while
doing this. 
> Flip side of this is that distcp -update option can not check file size before copying
data. It can only check for the existence of file. 
> So I propose if -compress option is given then file size is not checked.
> Also when we copy file appropriate extension needs to be added to file depending on compression
type.



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