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https://issues.apache.org/jira/browse/CASSANDRA-1902?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13012520#comment-13012520
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Pavel Yaskevich commented on CASSANDRA-1902:
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the story behind ordering I mentioned is that Pointer.getByteBuffer always
ensures native byte order and MappedByteBuffer always has Big Endian order so
we need to ensure byte order of the Pointer.getByteBuffer by setting it to Big
Endian, but this is not a case here - on my tests on the server with 2gb RAM
hosted on rackspace and on the server with high-memory and medium server hosted
on ec2 both gave me a better performance using Pointer.getByteArray and wrap
comparing to Pointer.getByteBuffer (and the getByteArray performance is almost
identical to our current version).
> 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: T Jake Luciani
> Fix For: 0.7.5, 0.8
>
> Attachments:
> 0001-CASSANDRA-1902-cache-migration-impl-with-config-option.txt,
> 1902-formatted.txt, 1902-per-column-migration-rebase2.txt,
> 1902-per-column-migration.txt, CASSANDRA-1902-v3.patch,
> CASSANDRA-1902-v4.patch, CASSANDRA-1902-v5.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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