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https://issues.apache.org/jira/browse/HDFS-12000?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16086573#comment-16086573
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Chen Liang edited comment on HDFS-12000 at 7/13/17 11:23 PM:
-------------------------------------------------------------

Thank [~anu] for updating the doc!!

One question though (I think I asked this some time earlier). 4.1 only 
mentioned range put. I'm assuming seek() will be implemented here because the 
term streams is being used here. So what happens when I, say, write X bytes to 
location 10, then do a seek() to another location, say 100000, and write some Y 
bytes again? I guess this will be treated as two separate range put?If so, does 
it imply that we should always commit before seek() or anything? I think we 
talked about vectored IO here but I'm still not sure how will vectored IO help 
for this particular case. Because these two writes (before seek() and after 
seek()) can be any of the situations: disjoint, contiguous or overlap.

Another related question, do we allow seek to somewhere beyond current size of 
the key and write? e.g. write a block of 1000 bytes, which covered 0 ~ 999 
offset. Do we allow seek to some offset beyond 999 and write, say, write to 
2000 offset? Seems nothing prevents us from doing it though.


was (Author: vagarychen):
Thank [~anu] for updating the doc!!

One question though (I think I asked this some time earlier). 4.1 only 
mentioned range put. I'm assuming seek() will be implemented here because the 
term streams is being used here. So what happens when I, say, write X bytes to 
location 10, then do a seek() to another location, say 100000, and write some Y 
bytes again? I guess this will be treated as two separate range put?If so, does 
it imply that we should always commit before seek() or anything? I think we 
talked about vectored IO here but I'm still not sure how will vectored IO help 
for this particular case. Because these two writes (before seek() and after 
seek()) can be any of the situations: disjoint, contiguous or overlap.

> Ozone: Container : Add key versioning support
> ---------------------------------------------
>
>                 Key: HDFS-12000
>                 URL: https://issues.apache.org/jira/browse/HDFS-12000
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: ozone
>    Affects Versions: HDFS-7240
>            Reporter: Anu Engineer
>            Assignee: Chen Liang
>         Attachments: OzoneVersion.001.pdf
>
>
> The rest interface of ozone supports versioning of keys. This support comes 
> from the containers and how chunks are managed to support this feature. This 
> JIRA tracks that feature. Will post a detailed design doc so that we can talk 
> about this feature.



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