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https://issues.apache.org/jira/browse/HADOOP-5744?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12709624#action_12709624
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Hairong Kuang commented on HADOOP-5744:
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Flush needs to make data visible before a block is completed. This has changed
a lot of assumptions in HDFS. Previous append work has put tremendous amount of
great work and set up a foundation for improvement. However there are issues
that seemed trivial initially but it turned out that they needed a thorough
design. HADOOP-4379, 4663, 5027, 5133, and 4692 etc. were filed as bugs but are
indeed caused by a lack of design. This issue aims at a design which solves
them all. It's targeted for 0.21.
If no hflush is called, dfs client pushes data to datanodes when a packet is
filled up. The packet size is configurable with a default size of 64K.
> Revisit append
> --------------
>
> Key: HADOOP-5744
> URL: https://issues.apache.org/jira/browse/HADOOP-5744
> Project: Hadoop Core
> Issue Type: Improvement
> Components: dfs
> Affects Versions: 0.20.0
> Reporter: Hairong Kuang
> Assignee: Hairong Kuang
> Fix For: 0.21.0
>
> Attachments: AppendSpec.pdf
>
>
> HADOOP-1700 and related issues have put a lot of efforts to provide the first
> implementation of append. However, append is such a complex feature. It turns
> out that there are issues that were initially seemed trivial but needs a
> careful design. This jira revisits append, aiming for a design and
> implementation supporting a semantics that are acceptable to its users.
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