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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