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From "Jonathan Ellis (JIRA)" <>
Subject [jira] Commented: (CASSANDRA-678) row-level cache
Date Sat, 09 Jan 2010 04:41:02 GMT


Jonathan Ellis commented on CASSANDRA-678:

    to provide similar visibility into keycache performance, combines SSTable keycaches into
one at CFS level.  This results in losing most of the performance gains of using a key cache.
 I've included this in case someone sees something obviously dumb I did, but it's definitely
not good to apply in current form.

    make rowcache, keycache configurable per-CF

    row cache jmx instrumentation (size, hit rate)

    clean up onstart to fix cache size calculation

    basic row caching

> row-level cache
> ---------------
>                 Key: CASSANDRA-678
>                 URL:
>             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
> 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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