[ http://issues.apache.org/jira/browse/HADOOP-54?page=all ]
Arun C Murthy updated HADOOP-54:
--------------------------------
Attachment: SequenceFile.20060821.perfomance.txt
Doug - here's another patch incorporating the fix (lazy initialization of the
inflater) plus your other suggestions.
I've also attached results of a quick test run of SequenceFile-v3 v/s
SequenceFile-v4 (2 runs of 10k and 100k records respectively). Within that
framework it seems reasonable to assume that creating one ValueBytes object
per-record doesn't show up blatantly (of course we can further iterate on
this); IAC there is a safety net for extreme corner cases
(http://issues.apache.org/jira/browse/HADOOP-54#action_12425953).
PS: The existing TestSequenceFile.java in trunk doesn't pass along the
'compress' flag to mergeTest - I ran the tests after fixing it; the patch
reflects that too. Just fyi.
> 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.updated.final.patch,
> 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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