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https://issues.apache.org/jira/browse/FLINK-9749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16935703#comment-16935703
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Kostas Kloudas commented on FLINK-9749:
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Hi [~dangdangdang]! We just merged
https://issues.apache.org/jira/browse/FLINK-13864 to the master which allows to
extend the {{StreamingFileSink}}.
Essentially with this change we aim to allow users to implement their specific
need on top of the {{StreamingFileSink}} without requiring (hopefully) changes
to Flink itself.
Please have a look and let us know if this allows you to implement your usecase
and if not, let us know what is missing.
> Rework Bucketing Sink
> ---------------------
>
> Key: FLINK-9749
> URL: https://issues.apache.org/jira/browse/FLINK-9749
> Project: Flink
> Issue Type: New Feature
> Components: Connectors / FileSystem
> Reporter: Stephan Ewen
> Assignee: Kostas Kloudas
> Priority: Major
>
> The BucketingSink has a series of deficits at the moment.
> Due to the long list of issues, I would suggest to add a new
> StreamingFileSink with a new and cleaner design
> h3. Encoders, Parquet, ORC
> - It only efficiently supports row-wise data formats (avro, jso, sequence
> files.
> - Efforts to add (columnar) compression for blocks of data is inefficient,
> because blocks cannot span checkpoints due to persistence-on-checkpoint.
> - The encoders are part of the \{{flink-connector-filesystem project}},
> rather than in orthogonal formats projects. This blows up the dependencies of
> the \{{flink-connector-filesystem project}} project. As an example, the
> rolling file sink has dependencies on Hadoop and Avro, which messes up
> dependency management.
> h3. Use of FileSystems
> - The BucketingSink works only on Hadoop's FileSystem abstraction not
> support Flink's own FileSystem abstraction and cannot work with the packaged
> S3, maprfs, and swift file systems
> - The sink hence needs Hadoop as a dependency
> - The sink relies on "trying out" whether truncation works, which requires
> write access to the users working directory
> - The sink relies on enumerating and counting files, rather than maintaining
> its own state, making less efficient
> h3. Correctness and Efficiency on S3
> - The BucketingSink relies on strong consistency in the file enumeration,
> hence may work incorrectly on S3.
> - The BucketingSink relies on persisting streams at intermediate points.
> This is not working properly on S3, hence there may be data loss on S3.
> h3. .valid-length companion file
> - The valid length file makes it hard for consumers of the data and should
> be dropped
> We track this design in a series of sub issues.
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