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https://issues.apache.org/jira/browse/HADOOP-16085?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16758672#comment-16758672
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Sean Mackrory commented on HADOOP-16085:
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Thanks for submitting a patch [~ben.roling]. Haven't had a chance to do a full
review yet, but one of [~fabbri]'s comments was also high on my list of things
to watch out for:
{quote}Backward / forward compatible with existing S3Guarded buckets and Dynamo
tables.{quote}
Specifically, we need to gracefully deal with any row missing an object
version. The other direction is easy - if this simply adds a new field, old
code will ignore it and we'll continue to get the current behavior.
My other concern is that this requires enabling object versioning. I know
[~fabbri] has done some testing with that and I think eventually hit issues.
Was it just a matter of the space all the versions were taking up, or was it
actually a performance problem once there was enough overhead?
> S3Guard: use object version to protect against inconsistent read after
> replace/overwrite
> ----------------------------------------------------------------------------------------
>
> Key: HADOOP-16085
> URL: https://issues.apache.org/jira/browse/HADOOP-16085
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 3.2.0
> Reporter: Ben Roling
> Priority: Major
> Attachments: HADOOP-16085_3.2.0_001.patch
>
>
> Currently S3Guard doesn't track S3 object versions. If a file is written in
> S3A with S3Guard and then subsequently overwritten, there is no protection
> against the next reader seeing the old version of the file instead of the new
> one.
> It seems like the S3Guard metadata could track the S3 object version. When a
> file is created or updated, the object version could be written to the
> S3Guard metadata. When a file is read, the read out of S3 could be performed
> by object version, ensuring the correct version is retrieved.
> I don't have a lot of direct experience with this yet, but this is my
> impression from looking through the code. My organization is looking to
> shift some datasets stored in HDFS over to S3 and is concerned about this
> potential issue as there are some cases in our codebase that would do an
> overwrite.
> I imagine this idea may have been considered before but I couldn't quite
> track down any JIRAs discussing it. If there is one, feel free to close this
> with a reference to it.
> Am I understanding things correctly? Is this idea feasible? Any feedback
> that could be provided would be appreciated. We may consider crafting a
> patch.
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