[jira] [Created] (IGNITE-16013) Calcite engine. Introduce sort-with-limit physical relational operator

["Aleksey Plekhanov (Jira)" <ji...@apache.org>]

Aleksey Plekhanov created IGNITE-16013:
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             Summary: 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


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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