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https://issues.apache.org/jira/browse/HADOOP-15625?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Steve Loughran updated HADOOP-15625:
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Resolution: Fixed
Status: Resolved (was: Patch Available)
Patch backported into branch-3.2, closing as done!
thank you to everyone who helped here -it's been through a few iterations and
now I'm happy. I'm also staring at other bits of the code thinking "if we want
to consistently propagate etag data, how do I do it"....
> S3A input stream to use etags/version number to detect changed source files
> ---------------------------------------------------------------------------
>
> Key: HADOOP-15625
> URL: https://issues.apache.org/jira/browse/HADOOP-15625
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 3.2.0
> Reporter: Brahma Reddy Battula
> Assignee: Ben Roling
> Priority: Major
> Fix For: 3.3.0, 3.2.1
>
> Attachments: HADOOP--15625-006.patch, HADOOP-15625-001.patch,
> HADOOP-15625-002.patch, HADOOP-15625-003.patch, HADOOP-15625-004.patch,
> HADOOP-15625-005.patch, HADOOP-15625-006.patch, HADOOP-15625-007.patch,
> HADOOP-15625-008.patch, HADOOP-15625-009.patch, HADOOP-15625-010.patch,
> HADOOP-15625-011.patch, HADOOP-15625-012.patch, HADOOP-15625-013-delta.patch,
> HADOOP-15625-013.patch, HADOOP-15625-014.patch, HADOOP-15625-015.patch,
> HADOOP-15625-015.patch, HADOOP-15625-016.patch, HADOOP-15625-017.patch,
> HADOOP-15625-branch-3.2-018.patch
>
>
> S3A input stream doesn't handle changing source files any better than the
> other cloud store connectors. Specifically: it doesn't noticed it has
> changed, caches the length from startup, and whenever a seek triggers a new
> GET, you may get one of: old data, new data, and even perhaps go from new
> data to old data due to eventual consistency.
> We can't do anything to stop this, but we could detect changes by
> # caching the etag of the first HEAD/GET (we don't get that HEAD on open with
> S3Guard, BTW)
> # on future GET requests, verify the etag of the response
> # raise an IOE if the remote file changed during the read.
> It's a more dramatic failure, but it stops changes silently corrupting things.
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