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https://issues.apache.org/jira/browse/CASSANDRA-4937?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13577990#comment-13577990
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Pavel Yaskevich commented on CASSANDRA-4937:
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I just don't want to make situation when latencies suddenly spike and stayed in
that state but there is no indication what is going on (the explanation is that
rows exceeded page threshold and preheat was turned off).
> 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: 1.2.2
>
> Attachments: 4937-v3.txt, CASSANDRA-4937.patch,
> CASSANDRA-4937-trunk.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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