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https://issues.apache.org/jira/browse/CASSANDRA-1902?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13079401#comment-13079401
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Jason Rutherglen commented on CASSANDRA-1902:
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I think we can revive this issue leveraging the [same] work Lucene has
performed in this area at [1]. Apparently O_DIRECT is the flag that will work.
Perhaps we should open a new issue?
1. https://issues.apache.org/jira/browse/LUCENE-2500
2.
https://builds.apache.org/job/Lucene-trunk/javadoc/all/org/apache/lucene/store/DirectIOLinuxDirectory.html
> Migrate cached pages during compaction
> ---------------------------------------
>
> Key: CASSANDRA-1902
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1902
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Affects Versions: 0.7.1
> Reporter: T Jake Luciani
> Assignee: Pavel Yaskevich
> Fix For: 1.0
>
> Attachments:
> 0001-CASSANDRA-1902-cache-migration-impl-with-config-option.txt,
> 1902-BufferedSegmentedFile-logandsleep.txt, 1902-formatted.txt,
> 1902-per-column-migration-rebase2.txt, 1902-per-column-migration.txt,
> CASSANDRA-1902-v10-trunk-rebased.patch, CASSANDRA-1902-v3.patch,
> CASSANDRA-1902-v4.patch, CASSANDRA-1902-v5.patch, CASSANDRA-1902-v6.patch,
> CASSANDRA-1902-v7.patch, CASSANDRA-1902-v8.patch,
> CASSANDRA-1902-v9-trunk-rebased.patch,
> CASSANDRA-1902-v9-trunk-with-jmx.patch, CASSANDRA-1902-v9-trunk.patch,
> CASSANDRA-1902-v9.patch
>
> Original Estimate: 32h
> Time Spent: 56h
> Remaining Estimate: 0h
>
> Post CASSANDRA-1470 there is an opportunity to migrate cached pages from a
> pre-compacted CF during the compaction process. This is now important since
> CASSANDRA-1470 caches effectively nothing.
> For example an active CF being compacted hurts reads since nothing is cached
> in the new SSTable.
> The purpose of this ticket then is to make sure SOME data is cached from
> active CFs. This can be done my monitoring which Old SSTables are in the page
> cache and caching active rows in the New SStable.
> A simpler yet similar approach is described here:
> http://insights.oetiker.ch/linux/fadvise/
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