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From "Sylvain Lebresne (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-9471) Columns should be backed by a BTree, not an array
Date Fri, 03 Jul 2015 09:18:05 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-9471?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14613046#comment-14613046
] 

Sylvain Lebresne commented on CASSANDRA-9471:
---------------------------------------------

bq.  at the very least, the improved iterator, improved tests, and wider deployment of the
btree are all worth incorporating.

What about moving those changes to a separate ticket (i.e. one that is not concerned by {{Columns}})?
It's useful to trunk anyway as you says, and the less stuff we delay, the better. Splitting
the changes related to {{Columns}} from the other is also more incremental in a way :)

> Columns should be backed by a BTree, not an array
> -------------------------------------------------
>
>                 Key: CASSANDRA-9471
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-9471
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Benedict
>            Assignee: Benedict
>             Fix For: 3.0 beta 1
>
>
> Follow up to 8099. 
> We have pretty terrible lookup performance as the number of columns grows (linear). In
at least one location, this results in quadratic performance. 
> We don't however want this structure to be either any more expensive to build, nor to
store. Some small modifications to BTree will permit it to serve here, by permitting efficient
lookup by index, and calculation _of_ index for a given key.



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