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From "Benedict (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6933) Optimise Read Comparison Costs in collectTimeOrderedData
Date Wed, 02 Apr 2014 22:59:17 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6933?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13958295#comment-13958295
] 

Benedict commented on CASSANDRA-6933:
-------------------------------------

LGTM, assuming the only changes are in ABSC.SearchIter

I'm not sure the assert i2 != 0 buys us anything, it's pretty much provable it cannot ever
be 0 (we have complete control over its value here), and even if we get it wrong it doesn't
really stop anything bad happening (if we've got that wrong, we can still get i2 < i, which
is just as bad)



> Optimise Read Comparison Costs in collectTimeOrderedData
> --------------------------------------------------------
>
>                 Key: CASSANDRA-6933
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6933
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Benedict
>            Assignee: Benedict
>            Priority: Minor
>              Labels: performance
>             Fix For: 2.1
>
>         Attachments: 6933-v3.txt, 6933-v4.txt
>
>
> Introduce a new SearchIterator construct, which can be obtained from a ColumnFamily,
which permits efficiently iterating a subset of the cells in ascending order. Essentially,
it saves the previously visited position and searches from there, but also tries to avoid
searching the whole remaining space if possible.



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