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https://issues.apache.org/jira/browse/HADOOP-19233?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Anuj Modi resolved HADOOP-19233.
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Fix Version/s: 3.5.0
3.4.2
Target Version/s: 3.4.1, 3.5.0 (was: 3.5.0, 3.4.1)
Resolution: Fixed
> ABFS: [FnsOverBlob] Implementing Rename and Delete APIs over Blob Endpoint
> --------------------------------------------------------------------------
>
> Key: HADOOP-19233
> URL: https://issues.apache.org/jira/browse/HADOOP-19233
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/azure
> Affects Versions: 3.4.0
> Reporter: Anuj Modi
> Assignee: Manish Bhatt
> Priority: Major
> Labels: pull-request-available
> Fix For: 3.5.0, 3.4.2
>
>
> Currently, we only support rename and delete operations on the DFS endpoint.
> The reason for supporting rename and delete operations on the Blob endpoint
> is that the Blob endpoint does not account for hierarchy. We need to ensure
> that the HDFS contracts are maintained when performing rename and delete
> operations. Renaming or deleting a directory over the Blob endpoint requires
> the client to handle the orchestration and rename or delete all the blobs
> within the specified directory.
>
> The task outlines the considerations for implementing rename and delete
> operations for the FNS-blob endpoint to ensure compatibility with HDFS
> contracts.
> * {*}Blob Endpoint Usage{*}: The task addresses the need for abstraction in
> the code to maintain HDFS contracts while performing rename and delete
> operations on the blob endpoint, which does not support hierarchy.
> * {*}Rename Operations{*}: The {{AzureBlobFileSystem#rename()}} method will
> use a {{RenameHandler}} instance to handle rename operations, with separate
> handlers for the DFS and blob endpoints. This method includes prechecks,
> destination adjustments, and orchestration of directory renaming for blobs.
> * {*}Atomic Rename{*}: Atomic renaming is essential for blob endpoints, as
> it requires orchestration to copy or delete each blob within the directory. A
> configuration will allow developers to specify directories for atomic
> renaming, with a JSON file to track the status of renames.
> * {*}Delete Operations{*}: Delete operations are simpler than renames,
> requiring fewer HDFS contract checks. For blob endpoints, the client must
> handle orchestration, including managing orphaned directories created by
> Az-copy.
> * {*}Orchestration for Rename/Delete{*}: Orchestration for rename and delete
> operations over blob endpoints involves listing blobs and performing actions
> on each blob. The process must be optimized to handle large numbers of blobs
> efficiently.
> * {*}Need for Optimization{*}: Optimization is crucial because the
> {{ListBlob}} API can return a maximum of 5000 blobs at once, necessitating
> multiple calls for large directories. The task proposes a producer-consumer
> model to handle blobs in parallel, thereby reducing processing time and
> memory usage.
> * {*}Producer-Consumer Design{*}: The proposed design includes a producer to
> list blobs, a queue to store the blobs, and a consumer to process them in
> parallel. This approach aims to improve efficiency and mitigate memory issues.
> More details will follow
> Perquisites for this Patch:
> 1. HADOOP-19187 ABFS: [FnsOverBlob]Making AbfsClient Abstract for supporting
> both DFS and Blob Endpoint - ASF JIRA (apache.org)
> 2. HADOOP-19226 ABFS: [FnsOverBlob]Implementing Azure Rest APIs on Blob
> Endpoint for AbfsBlobClient - ASF JIRA (apache.org)
> 3. HADOOP-19207 ABFS: [FnsOverBlob]Response Handling of Blob Endpoint APIs
> and Metadata APIs - ASF JIRA (apache.org)
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