[jira] Commented: (CASSANDRA-350) optimize away unnecessary range scans

["Jonathan Ellis (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-350?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12768947#action_12768947 ] 

Jonathan Ellis commented on CASSANDRA-350:
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ok, that is fine so far.  the "optimize away the slice" means we should avoid reading an entire block of columns in the Reader when the index information combined with start,finish means there can't possibly be a matching column.

> optimize away unnecessary range scans
> -------------------------------------
>
>                 Key: CASSANDRA-350
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-350
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Gary Dusbabek
>             Fix For: 0.5
>
>         Attachments: cassandra-350.patch
>
>
> Even when a the columns exist for a given key, they usually won't exist in all the sstable segments.  So avoiding the scan when the column index shows we can, will be a win.
> This is what the todo in SSTableSliceIterator is about:
>         // TODO push finishColumn down here too, so we can tell when we're done and optimize away the slice when the index + start/stop shows there's nothing to scan for

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