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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-4297) Use java NIO as much as possible when streaming compressed SSTables
Date Thu, 31 May 2012 02:28:23 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-4297?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13286271#comment-13286271
] 

Jonathan Ellis commented on CASSANDRA-4297:
-------------------------------------------

bq. Most of the time was spent on source node waiting for dest node to decompress and write
to disk

It looks like the only reason to decompress is to compare crc32...  is that right?  Why did
we crc uncompressed data instead of compressed?  Should we introduce a new version of snappy
compression that CRCs the compressed data instead?
                
> Use java NIO as much as possible when streaming compressed SSTables
> -------------------------------------------------------------------
>
>                 Key: CASSANDRA-4297
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4297
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Yuki Morishita
>            Assignee: Yuki Morishita
>            Priority: Minor
>              Labels: streaming
>             Fix For: 1.2
>
>
> Back in 0.8, streaming uses java NIO (FileChannel#transferTo/transferFrom) to perform
zero copy file transfer between nodes. Since 1.0, in order to add new features like sstable
compression and internode encryption we had to switch to java IO Input/OutputStreams. What
we currently do to transfer compressed SSTable is, in source node, 1) decompress chunk in
SSTable, 2) compress using LZF for network, and in destination node, 3) decompress using LZF
as reading from socket, 4) compress for SSTable on disk.
> Now, 1.1 comes out with SSTable compression turned on by default. It is reasonable to
transfer compressed file as is using NIO instead of decompress/compress in source node.

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