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From "Ryan King (JIRA)" <j...@apache.org>
Subject [jira] Commented: (CASSANDRA-678) row-level cache
Date Mon, 11 Jan 2010 17:50:54 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-678?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12798744#action_12798744
] 

Ryan King commented on CASSANDRA-678:
-------------------------------------

It would be nice if the capacity configuration was in absolute size, rather than a fraction
of the CF size. In other words, I'd like to be able to configure cassandra like "use 1GB of
row cache per CF". Obviously, as your data set gets bigger, your cache hit ratios will go
down (assuming your traffic distribution stays relatively uniform).

Otherwise, I think this looks awesome, this will really help us. 

> row-level cache
> ---------------
>
>                 Key: CASSANDRA-678
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-678
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Jonathan Ellis
>            Priority: Minor
>             Fix For: 0.9
>
>         Attachments: 0001-basic-caching.txt, 0002-clean-up-onstart-to-fix-cache-size-calculation.txt,
0003-instrumentation.txt, 0004-make-rowcache-keycache-configurable-per-CF.txt, 0005-combine-SSTable-keycaches-into-one-at-CFS-level.-do-no.txt,
0005-update-cached-rows-in-place-instead-of-invalidating-.patch
>
>
> We have a key cache but that doesn't help mitigate the expensive deserialization of the
actual data to return.
> Adding a row-level cache should be fairly simple using a ConcurrentLinkedHashMap<String
[key], ColumnFamily> structure.  (We will only cache whole rows at a time, since already
know how to query on those in-memory.  This limits us to CFs full of narrow rows but that
is a common enough use case to be worth tackling if it can be done simply enough.)

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