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From "Arun C Murthy (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-54) SequenceFile should compress blocks, not individual entries
Date Thu, 24 Aug 2006 20:15:02 GMT
     [ http://issues.apache.org/jira/browse/HADOOP-54?page=all ]

Arun C Murthy updated HADOOP-54:
--------------------------------

    Attachment: SequenceFile20060824.tgz

Here's the latest patch incorporating Owen's quibble about the enum, also I have added a -rwonly
option to TestSequenceFile.java and attached results of just read/write tests on seq3 and
seq4.

> SequenceFile should compress blocks, not individual entries
> -----------------------------------------------------------
>
>                 Key: HADOOP-54
>                 URL: http://issues.apache.org/jira/browse/HADOOP-54
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: io
>    Affects Versions: 0.2.0
>            Reporter: Doug Cutting
>         Assigned To: Arun C Murthy
>             Fix For: 0.6.0
>
>         Attachments: SequenceFile.20060821.patch, SequenceFile.20060821.perfomance.txt,
SequenceFile.20060822.tgz, SequenceFile.updated.final.patch, SequenceFile20060824.tgz, SequenceFiles.final.patch,
SequenceFiles.patch, SequenceFilesII.patch, VIntCompressionResults.txt
>
>
> SequenceFile will optionally compress individual values.  But both compression and performance
would be much better if sequences of keys and values are compressed together.  Sync marks
should only be placed between blocks.  This will require some changes to MapFile too, so that
all file positions stored there are the positions of blocks, not entries within blocks.  Probably
this can be accomplished by adding a getBlockStartPosition() method to SequenceFile.Writer.

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