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From "Stu Hood (JIRA)" <j...@apache.org>
Subject [jira] Commented: (CASSANDRA-1255) Explore interning keys and column names
Date Sun, 23 Jan 2011 04:31:45 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-1255?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12985243#action_12985243
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Stu Hood commented on CASSANDRA-1255:
-------------------------------------

* I'm not sure I understand the reasoning behind not interning super column names, though
they should probably be interned in a separate pool
* It might be worthwhile to add logic to periodically clear the pool if it is full (memtable
flush count % x or something): workloads might change over time

> Explore interning keys and column names
> ---------------------------------------
>
>                 Key: CASSANDRA-1255
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1255
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Stu Hood
>            Assignee: Jonathan Ellis
>            Priority: Minor
>             Fix For: 0.7.1
>
>         Attachments: 1255-v2.txt, 1255-v3.txt, 1255.txt
>
>   Original Estimate: 8h
>  Remaining Estimate: 8h
>
> With multiple Memtables, key caches and row caches holding DecoratedKey references, it
could potentially be a huge memory savings (and relief to GC) to intern DecoratedKeys. Taking
the idea farther, for the skinny row pattern, and for certain types of wide row patterns,
interning of column names could be very beneficial as well (although we would need to wrap
the byte[]s in something for hashCode/equals).
> This ticket should explore the benefits and overhead of interning.
> Google collections/guava MapMaker is a very convenient way to create this type of cache:
example call: http://stackoverflow.com/questions/2865026/use-permgen-space-or-roll-my-own-intern-method/2865083#2865083

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