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From "stack (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-5744) Revisit append
Date Mon, 18 May 2009 23:34:45 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-5744?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12710541#action_12710541
] 

stack commented on HADOOP-5744:
-------------------------------

@ Hairong

.bq My question is that why the file needs to be closed before it is read. 

It doesn't have to be closed as long the reader is able to go all the ways up to the last
sync made by the writer before crash.

.bq Is it OK for your client to trigger the close of the file but does not wait for it to
close? 

Yes, as long as the reader is able to go all the ways up to the last sync made....

.bq (1) may have more bytes than when it was previously read. This is a norm case. Will this
be an issue to hbase?

How would this circumstance arise?

.bq Note that the current implementation in 0.20 does not provide the second guarantee described
above. 

In my testing of hadoop-4379, i've only been killing the writer application. I should play
with killing the writer application AND the local datanode.

> 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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