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From "Edward Capriolo (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-4175) Reduce memory, disk space, and cpu usage with a column name/id map
Date Sat, 08 Jun 2013 02:37:22 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-4175?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13678651#comment-13678651
] 

Edward Capriolo commented on CASSANDRA-4175:
--------------------------------------------

It also sounds like we are re-opening up the concept of plugable storage. https://issues.apache.org/jira/browse/CASSANDRA-2995
since we are talking about custom disk formats only good for specific use cases.
                
> Reduce memory, disk space, and cpu usage with a column name/id map
> ------------------------------------------------------------------
>
>                 Key: CASSANDRA-4175
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4175
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Jonathan Ellis
>             Fix For: 2.1
>
>
> We spend a lot of memory on column names, both transiently (during reads) and more permanently
(in the row cache).  Compression mitigates this on disk but not on the heap.
> The overhead is significant for typical small column values, e.g., ints.
> Even though we intern once we get to the memtable, this affects writes too via very high
allocation rates in the young generation, hence more GC activity.
> Now that CQL3 provides us some guarantees that column names must be defined before they
are inserted, we could create a map of (say) 32-bit int column id, to names, and use that
internally right up until we return a resultset to the client.

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