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From "Arun C Murthy (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-441) SequenceFile should support 'custom compressors'
Date Mon, 28 Aug 2006 11:12:23 GMT
    [ http://issues.apache.org/jira/browse/HADOOP-441?page=comments#action_12430966 ] 
            
Arun C Murthy commented on HADOOP-441:
--------------------------------------

Doug,

  If I'm not missing something here... we can reuse the compressor by having one 'Deflater/Inflater'
object per Writer/Reader instead of the pool right? Even then creating the stream with the
above compressor will probably be quite significant for RecordCompressWriter where we would
need to do this per record? Appreciate any further details on this one.

 Also, I'm concerned this solution will be quite gzip specific, which be unsuitable for a
generic 'custom' compressor... thoughts?

> SequenceFile should support 'custom compressors'
> ------------------------------------------------
>
>                 Key: HADOOP-441
>                 URL: http://issues.apache.org/jira/browse/HADOOP-441
>             Project: Hadoop
>          Issue Type: New Feature
>          Components: io
>            Reporter: Arun C Murthy
>         Assigned To: Arun C Murthy
>             Fix For: 0.6.0
>
>
> SequenceFiles should support 'custom compressors' which can be specified by the user
on creation of the file. 
> Readily available packages for gzip and zip (java.util.zip) are among obvious choices
to support. Of course there will be hooks so that other compressors can be added in future
as long as there is a way to construct (input/output) streams on top of the compressor/decompressor.
> The 'classname' of the 'custom compressor/decompressor' could be stored in the header
of the SequenceFile which can then be used by SequenceFile.Reader to figure out the appropriate
'decompressor'. Thus I propose we add constructors to SequenceFile.Writer which take in the
'classname' of the compressor's input/output stream classes (e.g. DeflaterOutputStream/InflaterInputStream
or GZIPOutputStream/GZIPInputStream), which acts as the hook for future compressors/decompressors.

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