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From "Benedict (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6281) Use Atomic*FieldUpdater to save memory
Date Thu, 02 Jan 2014 16:37:51 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6281?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13860315#comment-13860315
] 

Benedict commented on CASSANDRA-6281:
-------------------------------------

Just for absolute correctness, I'll clarify: 

Current overhead per column is around 100 bytes, plus a little extra for the row as a whole.
This will save around 16 bytes on average per row in memtable (the readcallbacks/writehandlers
are too short lived to be a major impact at all). So in a table with only 1 almost empty column
this might be a large saving, 10-15%, but it goes down rapidly. And I doubt many people have
tables with fewer than 4-5 columns, at which point it's about 4% excluding the data itself
(so maybe 3% including it), and getting smaller with each column / size of payload.

> Use Atomic*FieldUpdater to save memory
> --------------------------------------
>
>                 Key: CASSANDRA-6281
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6281
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Marcus Eriksson
>            Assignee: Marcus Eriksson
>            Priority: Minor
>             Fix For: 2.1
>
>         Attachments: 0001-Use-Atomic-FieldUpdater-to-save-memory.patch
>
>
> Followup to CASSANDRA-6278, use Atomic*FieldUpdater in;
> AtomicSortedColumns
> ReadCallback
> WriteResponseHandler



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