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https://issues.apache.org/jira/browse/CASSANDRA-4937?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Pavel Yaskevich updated CASSANDRA-4937:
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Attachment: CASSANDRA-4937-trunk.patch
Patch (based on trunk) removes skip cache from readers and adds advice on
SSTableReader last dereference and preheating if key cache was enabled.
> 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
> Fix For: 1.2.2
>
> Attachments: 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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