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https://issues.apache.org/jira/browse/CASSANDRA-4937?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13609284#comment-13609284
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Pavel Yaskevich edited comment on CASSANDRA-4937 at 3/21/13 6:37 PM:
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There is only one place where shouldPreheatPageCache() is used
(CompactionTask:233) it shouldn't anyhow prevent key cache from being populated
after compaction, that only could be done by getPreheatKeyCache() flag in
config.
was (Author: xedin):
There is only once place where shouldPreheatPageCache() is used
(CompactionTask:233) it shouldn't anyhow affect key cache from being populated,
that only could be done by getPreheatKeyCache() flag in config.
> CRAR improvements (object cache + CompressionMetadata chunk offset storage
> moved off-heap).
> -------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-4937
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4937
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Pavel Yaskevich
> Assignee: Pavel Yaskevich
> Labels: core
> Fix For: 1.2.4
>
> Attachments: 4937-v3.txt, CASSANDRA-4937.patch,
> CASSANDRA-4937-trunk.patch, CASSANDRA-4937-v4.patch
>
>
> After good amount of testing on one of the clusters it was found that in
> order to improve read latency we need to minimize allocation rate that
> compression involves, that minimizes GC (as well as heap usage) and
> substantially decreases latency on read heavy workloads.
> I have also discovered that RAR skip cache harms performance in situation
> when reads are done in parallel with compaction working with relatively big
> SSTable files (few GB and more). The attached patch removes possibility to
> skip cache from compressed files (I can also add changes to RAR to remove
> skip cache functionality as a separate patch).
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