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https://issues.apache.org/jira/browse/CALCITE-3920?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17082493#comment-17082493
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Stamatis Zampetakis commented on CALCITE-3920:
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Totally, I am thinking something around these lines :)
> Improve ORDER BY computation in Enumerable convention by exploiting LIMIT
> -------------------------------------------------------------------------
>
> Key: CALCITE-3920
> URL: https://issues.apache.org/jira/browse/CALCITE-3920
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.22.0
> Reporter: Stamatis Zampetakis
> Assignee: Stamatis Zampetakis
> Priority: Major
> Fix For: 1.23.0
>
>
> There are many use-cases (pagination, top-k) relying on queries with an ORDER
> BY clause followed by a LIMIT.
> At the moment, the two operations are implemented independently the one from
> the other
> in the Enumerable convention. Even when we know that consumer needs only the
> top-10 results the sort operation will try to maintain its entire input
> sorted. The complexity of the sorting operation is O( n ) space and O( nlogn
> ) time, where n is the size of the input.
> By implementing ORDER BY and LIMIT together there are various optimizations
> that can be applied to reduce the space and time complexity of the sorting
> algorithm.
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