[jira] [Created] (CALCITE-4157) Use a different sort algorithm for EnumerableDefaults.orderBy(...)

["Thomas Rebele (Jira)" <ji...@apache.org>]

Thomas Rebele created CALCITE-4157:
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             Summary: Use a different sort algorithm for EnumerableDefaults.orderBy(...)
                 Key: CALCITE-4157
                 URL: https://issues.apache.org/jira/browse/CALCITE-4157
             Project: Calcite
          Issue Type: Improvement
            Reporter: Thomas Rebele


As shown by [the benchmarks|https://github.com/thomasrebele/jmh-micro-benchmarks/blob/98abccad8801532b78a0778cd7be7bd751f90da6/core-java/doc/jmh_partial_sort_jdk1.8.0_241.txt#L6793] for CALCITE-3920, the sort with a TreeMap is slower than sorting with Arrays.sort(Object[]). The latter takes about 35% less time than sorting with TreeMap over a randomized input. While the implementation is not exactly the same, it should be close enough to be able to say something about the performance of EnumerableDefaults.orderBy(...). The relevant results for this issue are the benchmarks with limit=-1 and algorithms treeMap and collectionSort.

The speedup might be even better if the input is already sorted, as modern VMs use TimSort, which checks if the input is already sorted.



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