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https://issues.apache.org/jira/browse/HDFS-11156?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16165687#comment-16165687
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Weiwei Yang commented on HDFS-11156:
------------------------------------
Hi [~shahrs87]
Thanks for sharing your concern, I think you are raising up a good point.
Current approach was trying to maintain compatibility as much as possible. We
don't want to modify any public APIs because it will cause a lot of problems on
upgrade/integrate paths. Ideally we could implement following API in
{{ClientProtocol}}
{code}
public BlockLocation[] getBlockLocations(String src,
long start, long length) throws IOException;
{code}
so that can be exposed via {{NamenodeRpcServer}} for {{NamenodeWebHdfsMethods}}
to call. However because of the compatibility concerns I am not sure if this is
worth to comparing to current path. It did a bit overhead on creating a dfs
client, it is more compatible.
Thanks
> Add new op GETFILEBLOCKLOCATIONS to WebHDFS REST API
> ----------------------------------------------------
>
> Key: HDFS-11156
> URL: https://issues.apache.org/jira/browse/HDFS-11156
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: webhdfs
> Affects Versions: 2.7.3
> Reporter: Weiwei Yang
> Assignee: Weiwei Yang
> Fix For: 2.9.0, 3.0.0-alpha2
>
> Attachments: BlockLocationProperties_JSON_Schema.jpg,
> BlockLocations_JSON_Schema.jpg, FileStatuses_JSON_Schema.jpg,
> HDFS-11156.01.patch, HDFS-11156.02.patch, HDFS-11156.03.patch,
> HDFS-11156.04.patch, HDFS-11156.05.patch, HDFS-11156.06.patch,
> HDFS-11156.07.patch, HDFS-11156.08.patch, HDFS-11156.09.patch,
> HDFS-11156.10.patch, HDFS-11156.11.patch, HDFS-11156.12.patch,
> HDFS-11156.13.patch, HDFS-11156.14.patch, HDFS-11156.15.patch,
> HDFS-11156.16.patch, HDFS-11156-branch-2.01.patch,
> Output_JSON_format_v10.jpg, SampleResponse_JSON.jpg
>
>
> Following webhdfs REST API
> {code}
> http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=GET_BLOCK_LOCATIONS&offset=0&length=1
> {code}
> will get a response like
> {code}
> {
> "LocatedBlocks" : {
> "fileLength" : 1073741824,
> "isLastBlockComplete" : true,
> "isUnderConstruction" : false,
> "lastLocatedBlock" : { ... },
> "locatedBlocks" : [ {...} ]
> }
> }
> {code}
> This represents for *o.a.h.h.p.LocatedBlocks*. However according to
> *FileSystem* API,
> {code}
> public BlockLocation[] getFileBlockLocations(Path p, long start, long len)
> {code}
> clients would expect an array of BlockLocation. This mismatch should be
> fixed. Marked as Incompatible change as this will change the output of the
> GET_BLOCK_LOCATIONS API.
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