> > Hello all. > > I have decided to explore more areas in which I can optimize and have added > two new benchmarks. Do you have any thoughts on this? > > postgres=# select bench_int16_sort(1000000); > bench_int16_sort > > > ----------------------------------------------------------------------------------------------------------------- > Time taken by usual sort: 66354981 ns, Time taken by optimized sort: > 52151523 ns, Percentage difference: 21.41% > (1 row) > > postgres=# select bench_float8_sort(1000000); > bench_float8_sort > > > ------------------------------------------------------------------------------------------------------------------ > Time taken by usual sort: 121475231 ns, Time taken by optimized sort: > 74458545 ns, Percentage difference: 38.70% > (1 row) >
Hello all We would like to see the relationship between the length of the sorted array and the performance gain, perhaps some graphs. We also want to see to set a "worst case" test, sorting the array in ascending order when it is initially descending Best, regards, Antoine Violin postgres=# > On Mon, Jul 15, 2024 at 10:32 AM Stepan Neretin <sncf...@gmail.com> wrote: > > > On Sat, Jun 8, 2024 at 1:50 AM Stepan Neretin <sncf...@gmail.com> wrote: > >> Hello all. >> >> I am interested in the proposed patch and would like to propose some >> additional changes that would complement it. My changes would introduce >> similar optimizations when working with a list of integers or object >> identifiers. Additionally, my patch includes an extension for >> benchmarking, which shows an average speedup of 30-40%. >> >> postgres=# SELECT bench_oid_sort(1000000); >> bench_oid_sort >> >> >> ---------------------------------------------------------------------------------------------------------------- >> Time taken by list_sort: 116990848 ns, Time taken by list_oid_sort: >> 80446640 ns, Percentage difference: 31.24% >> (1 row) >> >> postgres=# SELECT bench_int_sort(1000000); >> bench_int_sort >> >> >> ---------------------------------------------------------------------------------------------------------------- >> Time taken by list_sort: 118168506 ns, Time taken by list_int_sort: >> 80523373 ns, Percentage difference: 31.86% >> (1 row) >> >> What do you think about these changes? >> >> Best regards, Stepan Neretin. >> >> On Fri, Jun 7, 2024 at 11:08 PM Andrey M. Borodin <x4...@yandex-team.ru> >> wrote: >> >>> Hi! >>> >>> In a thread about sorting comparators[0] Andres noted that we have >>> infrastructure to help compiler optimize sorting. PFA attached PoC >>> implementation. I've checked that it indeed works on the benchmark from >>> that thread. >>> >>> postgres=# CREATE TABLE arrays_to_sort AS >>> SELECT array_shuffle(a) arr >>> FROM >>> (SELECT ARRAY(SELECT generate_series(1, 1000000)) a), >>> generate_series(1, 10); >>> >>> postgres=# SELECT (sort(arr))[1] FROM arrays_to_sort; -- original >>> Time: 990.199 ms >>> postgres=# SELECT (sort(arr))[1] FROM arrays_to_sort; -- patched >>> Time: 696.156 ms >>> >>> The benefit seems to be on the order of magnitude with 30% speedup. >>> >>> There's plenty of sorting by TransactionId, BlockNumber, OffsetNumber, >>> Oid etc. But this sorting routines never show up in perf top or something >>> like that. >>> >>> Seems like in most cases we do not spend much time in sorting. But >>> specialization does not cost us much too, only some CPU cycles of a >>> compiler. I think we can further improve speedup by converting inline >>> comparator to value extractor: more compilers will see what is actually >>> going on. But I have no proofs for this reasoning. >>> >>> What do you think? >>> >>> >>> Best regards, Andrey Borodin. >>> >>> [0] >>> https://www.postgresql.org/message-id/flat/20240209184014.sobshkcsfjix6u4r%40awork3.anarazel.de#fc23df2cf314bef35095b632380b4a59 >> >> > Hello all. > > I have decided to explore more areas in which I can optimize and have > added two new benchmarks. Do you have any thoughts on this? > > postgres=# select bench_int16_sort(1000000); > bench_int16_sort > > > ----------------------------------------------------------------------------------------------------------------- > Time taken by usual sort: 66354981 ns, Time taken by optimized sort: > 52151523 ns, Percentage difference: 21.41% > (1 row) > > postgres=# select bench_float8_sort(1000000); > bench_float8_sort > > > ------------------------------------------------------------------------------------------------------------------ > Time taken by usual sort: 121475231 ns, Time taken by optimized sort: > 74458545 ns, Percentage difference: 38.70% > (1 row) > > postgres=# > > Best regards, Stepan Neretin. >
