cassandra-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Matthew F. Dennis (JIRA)" <j...@apache.org>
Subject [jira] Commented: (CASSANDRA-2102) saved row cache doesn't save the cache
Date Wed, 09 Feb 2011 00:03:00 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-2102?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12992241#comment-12992241
] 

Matthew F. Dennis commented on CASSANDRA-2102:
----------------------------------------------

I really think safety is the way to go here (e.g. clone right before we put it into the cache).
 Not to mention cloning early would be generating memcopies for things we don't need to if
they never actually end up in the cache (e.g. things already in the cache, rejected by bloom
filters).

> saved row cache doesn't save the cache
> --------------------------------------
>
>                 Key: CASSANDRA-2102
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2102
>             Project: Cassandra
>          Issue Type: Bug
>    Affects Versions: 0.7.0
>            Reporter: Matthew F. Dennis
>            Assignee: Matthew F. Dennis
>             Fix For: 0.7.2
>
>         Attachments: 2102-cassandra-0.7-v2.txt, 2102-cassandra-0.7.txt
>
>
> saving row caches works by periodically iterating of the keySet() on the caches and writing
the keys for the cached contents to disk.  The cache keys are DecoratedKeys.  DecoratedKeys
contain a Token token and a ByteBuffer key.  The underlying buffer on the key gets reused
so the contents change.  This means that all the cache entries have distinct tokens but only
a handful of distinct key values.  This means that when the cache is loaded you only end up
loading a handful of keys instead of the ones actually in your cache.

-- 
This message is automatically generated by JIRA.
-
For more information on JIRA, see: http://www.atlassian.com/software/jira

        

Mime
View raw message