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Posted to dev@zookeeper.apache.org by "Steven Phillips (JIRA)" <ji...@apache.org> on 2014/02/26 01:52:20 UTC

[jira] [Resolved] (ZOOKEEPER-1889) Implement Top-N sort operator

     [ https://issues.apache.org/jira/browse/ZOOKEEPER-1889?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Steven Phillips resolved ZOOKEEPER-1889.
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    Resolution: Not A Problem

I meant to add this to the Drill jira, but accidently added it to the zookeeper. my apologies.

> Implement Top-N sort operator
> -----------------------------
>
>                 Key: ZOOKEEPER-1889
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1889
>             Project: ZooKeeper
>          Issue Type: Bug
>            Reporter: Steven Phillips
>
> When, for example, doing an order by with a limit, if limit << total, it would be much more efficient to maintain a priority queue instead of sorting the entire data set.
> In most cases, this will greatly reduce the number of comparisons, since most incoming records will not fall in the Top N, and thus will only require a single comparison operation. Incoming records that are in the Top-N will require at most log N comparisons.
> This will also allow periodic purging of record batches, reducing memory requirements.



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