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Posted to commits@cassandra.apache.org by "Jonathan Ellis (JIRA)" <ji...@apache.org> on 2013/03/30 00:15:16 UTC

[jira] [Commented] (CASSANDRA-4180) Single-pass compaction for LCR

    [ https://issues.apache.org/jira/browse/CASSANDRA-4180?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13617856#comment-13617856 ] 

Jonathan Ellis commented on CASSANDRA-4180:
-------------------------------------------

Ugh, this is almost straightforward.  But doing without column count is kind of a bitch.  Fortunately we can use 00/00 as the end-of-row marker since empty column names are not allowed.
                
> Single-pass compaction for LCR
> ------------------------------
>
>                 Key: CASSANDRA-4180
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4180
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Sylvain Lebresne
>            Assignee: Jason Brown
>              Labels: compaction
>             Fix For: 2.0
>
>
> LazilyCompactedRow reads all data twice to compact a row which is obviously inefficient. The main reason we do that is to compute the row header. However, CASSANDRA-2319 have removed the main part of that row header. What remains is the size in bytes and the number of columns, but it should be relatively simple to remove those, which would then remove the need for the two-phase compaction.

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