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https://issues.apache.org/jira/browse/HDFS-13186?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16514298#comment-16514298
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Chris Douglas commented on HDFS-13186:
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v010 just fixes javadoc errors and added more param javadoc for
{{MultipartUploader}}. I'm +1 on this and will commit if jenkins comes back
clean.
> [PROVIDED Phase 2] Multipart Uploader API
> -----------------------------------------
>
> Key: HDFS-13186
> URL: https://issues.apache.org/jira/browse/HDFS-13186
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Ewan Higgs
> Assignee: Ewan Higgs
> Priority: Major
> Attachments: HDFS-13186.001.patch, HDFS-13186.002.patch,
> HDFS-13186.003.patch, HDFS-13186.004.patch, HDFS-13186.005.patch,
> HDFS-13186.006.patch, HDFS-13186.007.patch, HDFS-13186.008.patch,
> HDFS-13186.009.patch, HDFS-13186.010.patch
>
>
> To write files in parallel to an external storage system as in HDFS-12090,
> there are two approaches:
> # Naive approach: use a single datanode per file that copies blocks locally
> as it streams data to the external service. This requires a copy for each
> block inside the HDFS system and then a copy for the block to be sent to the
> external system.
> # Better approach: Single point (e.g. Namenode or SPS style external client)
> and Datanodes coordinate in a multipart - multinode upload.
> This system needs to work with multiple back ends and needs to coordinate
> across the network. So we propose an API that resembles the following:
> {code:java}
> public UploadHandle multipartInit(Path filePath) throws IOException;
> public PartHandle multipartPutPart(InputStream inputStream,
> int partNumber, UploadHandle uploadId) throws IOException;
> public void multipartComplete(Path filePath,
> List<Pair<Integer, PartHandle>> handles,
> UploadHandle multipartUploadId) throws IOException;{code}
> Here, UploadHandle and PartHandle are opaque handlers in the vein of
> PathHandle so they can be serialized and deserialized in hadoop-hdfs project
> without knowledge of how to deserialize e.g. S3A's version of a UpoadHandle
> and PartHandle.
> In an object store such as S3A, the implementation is straight forward. In
> the case of writing multipart/multinode to HDFS, we can write each block as a
> file part. The complete call will perform a concat on the blocks.
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