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https://issues.apache.org/jira/browse/IGNITE-16013?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vladimir Steshin reassigned IGNITE-16013:
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Assignee: Vladimir Steshin
> Calcite engine. Introduce sort-with-limit physical relational operator
> ----------------------------------------------------------------------
>
> Key: IGNITE-16013
> URL: https://issues.apache.org/jira/browse/IGNITE-16013
> Project: Ignite
> Issue Type: Improvement
> Reporter: Aleksey Plekhanov
> Assignee: Vladimir Steshin
> Priority: Major
> Labels: calcite2-required, calcite3-required
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Currently, sort and limit are different physical relational operators, but in
> some cases, sort combined with a limit can be more effective. For example
> {{ORDER BY x LIMIT 1}} requires to store only one row and can be processed
> with {{O(rowsCount)}} operations. In general. {{ORDER BY x LIMIT m}} requires
> {{O(min(rowsCount, m))}} memory and have {{O(rowsCount * ln(min(rowsCount,
> m)))}} complexity.
> Since {{Limit}} node can't be moved below the {{Exchange}} node, {{ORDER BY x
> LIMIT m}} clause should produce two nodes: {{Limit}} node, with single
> distribution, and {{SortWithLimit}} node, which can be moved below the
> {{Exchange}} node and can reduce network traffic.
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