Manish Bhatt created HADOOP-19381:
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Summary: Support Rename and Delete operation over FNS-Blob endpoint
Key: HADOOP-19381
URL: https://issues.apache.org/jira/browse/HADOOP-19381
Project: Hadoop Common
Issue Type: New Feature
Components: fs/azure
Affects Versions: 3.5.0
Reporter: Manish Bhatt
Assignee: Manish Bhatt
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.
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