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https://issues.apache.org/jira/browse/HADOOP-6297?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12998681#comment-12998681
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Todd Lipcon commented on HADOOP-6297:
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Hrm, I guess what I don't understand is why we haven't needed this method for
existing file formats like SequenceFile that do block-based compression?
> Hadoop's support for zlib library lacks support to perform flushes
> (Z_SYNC_FLUSH and Z_FULL_FLUSH)
> --------------------------------------------------------------------------------------------------
>
> Key: HADOOP-6297
> URL: https://issues.apache.org/jira/browse/HADOOP-6297
> Project: Hadoop Common
> Issue Type: Improvement
> Components: io
> Reporter: Kevin J. Price
> Assignee: Kevin J. Price
> Priority: Minor
> Attachments: zlibpatch-0.3.patch, zlibpatch.patch
>
>
> The zlib library supports the ability to perform two types of flushes when
> deflating data. It can perform both a Z_SYNC_FLUSH, which forces all input to
> be written as output and byte-aligned and resets the Huffman coding, and it
> also supports a Z_FULL_FLUSH, which does the same thing but additionally
> resets the compression dictionary. The Hadoop wrapper for the zlib library
> does not support either of these two methods.
> Adding support should be fairly trivial. An additional deflate method that
> takes a fourth "flush" parameter, and a modification to the native c code to
> accept this fourth parameter and pass it along to the zlib library. I can
> submit a patch for this if desired.
> It should be noted that the native SUN Java API is likewise missing this
> functionality, as has been noted for over a decade here:
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4206909
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