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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-5863) In process (uncompressed) page cache
Date Tue, 22 Apr 2014 04:19:17 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-5863?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13976356#comment-13976356
] 

Jonathan Ellis commented on CASSANDRA-5863:
-------------------------------------------

bq. [[~xedin]] I have one more idea how to make it work, will keep you posted...

What was that?

bq. [[~benedict]] As to having a fast disk cache, I also think this is a great idea. But I
think it fits in as an extension of this and any compressed in-memory cache

+1 separate ticket (and a harder one IMO)

> In process (uncompressed) page cache
> ------------------------------------
>
>                 Key: CASSANDRA-5863
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5863
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>            Reporter: T Jake Luciani
>            Assignee: Pavel Yaskevich
>              Labels: performance
>             Fix For: 2.1 beta2
>
>
> Currently, for every read, the CRAR reads each compressed chunk into a byte[], sends
it to ICompressor, gets back another byte[] and verifies a checksum.  
> This process is where the majority of time is spent in a read request.  
> Before compression, we would have zero-copy of data and could respond directly from the
page-cache.
> It would be useful to have some kind of Chunk cache that could speed up this process
for hot data. Initially this could be a off heap cache but it would be great to put these
decompressed chunks onto a SSD so the hot data lives on a fast disk similar to https://github.com/facebook/flashcache.



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