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https://issues.apache.org/jira/browse/CASSANDRA-1470?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12928349#action_12928349
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Jonathan Ellis commented on CASSANDRA-1470:
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I think you could use Lucene's DirectIOLinuxIndexInput with only minor
modifications. It does alignment already as well as buffered seeks. It
extends DataInput which may be all we need, if not, extending it from
RandomAccessFile (just throw NotImplementedException on the write methods, we
don't care about those) should be easy.
It depends on Lucene's NativePosixUtil.open_direct but your fcntl approach
should work fine as well.
> use direct io for compaction
> ----------------------------
>
> Key: CASSANDRA-1470
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1470
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Jonathan Ellis
> Assignee: Pavel Yaskevich
> Fix For: 0.6.7, 0.7.1
>
> Attachments: 1470-v2.txt, 1470.txt, CASSANDRA-1470-for-0.6.patch,
> CASSANDRA-1470-v2.patch,
> CASSANDRA-1470-v3-0.7-with-LastErrorException-support.patch,
> CASSANDRA-1470.patch,
> use.DirectIORandomAccessFile.for.commitlog.against.1022235.patch
>
>
> When compaction scans through a group of sstables, it forces the data in the
> os buffer cache being used for hot reads, which can have a dramatic negative
> effect on performance.
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