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https://issues.apache.org/jira/browse/HADOOP-13887?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16287534#comment-16287534
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Steve Loughran commented on HADOOP-13887:
-----------------------------------------

I've been thinking about this.

# Once a file is opened, it's length is known (the initial getFileStatus() 
returns it, and it will come back on a header of the GET
# many of the uses of a file don't need to know the full length of a file until 
it's open. Specifically, when your code does an open(); seek(EOF-len(footer)); 
you don't need to know the EOF in advance. Partitioning does, though there a 
small diff in the length of the last partition is *probably* tractable.

In C you can open a file, do an explicit seek(offset from EOF), and, if you 
want to know the file length, do an ftell() once you are there.

# We could add a in interface+ method + streamCapabilities() option to return 
the length of an open file, e.g. {{public abstract long size() throws 
IOException;}}. (you can get this from a raw local stream, BTW).
# then code could be moved to using it, starting with the internal classes

> Encrypt S3A data client-side with AWS SDK
> -----------------------------------------
>
>                 Key: HADOOP-13887
>                 URL: https://issues.apache.org/jira/browse/HADOOP-13887
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: fs/s3
>    Affects Versions: 2.8.0
>            Reporter: Jeeyoung Kim
>            Assignee: Igor Mazur
>            Priority: Minor
>         Attachments: HADOOP-13887-002.patch, HADOOP-13887-007.patch, 
> HADOOP-13887-branch-2-003.patch, HADOOP-13897-branch-2-004.patch, 
> HADOOP-13897-branch-2-005.patch, HADOOP-13897-branch-2-006.patch, 
> HADOOP-13897-branch-2-008.patch, HADOOP-13897-branch-2-009.patch, 
> HADOOP-13897-branch-2-010.patch, HADOOP-13897-branch-2-012.patch, 
> HADOOP-13897-branch-2-014.patch, HADOOP-13897-trunk-011.patch, 
> HADOOP-13897-trunk-013.patch, HADOOP-14171-001.patch, S3-CSE Proposal.pdf
>
>
> Expose the client-side encryption option documented in Amazon S3 
> documentation  - 
> http://docs.aws.amazon.com/AmazonS3/latest/dev/UsingClientSideEncryption.html
> Currently this is not exposed in Hadoop but it is exposed as an option in AWS 
> Java SDK, which Hadoop currently includes. It should be trivial to propagate 
> this as a parameter passed to the S3client used in S3AFileSystem.java



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