út 18. 2. 2020 v 17:08 odesílatel Amit Langote <amitlangot...@gmail.com> napsal:
> On Tue, Feb 18, 2020 at 6:56 PM Amit Langote <amitlangot...@gmail.com> > wrote: > > On Tue, Feb 18, 2020 at 2:56 PM Pavel Stehule <pavel.steh...@gmail.com> > wrote: > > > út 18. 2. 2020 v 6:03 odesílatel Amit Langote <amitlangot...@gmail.com> > napsal: > > >> I didn't send the patch, because it didn't handle the cases where a > > >> simple expression consists of an inline-able function(s) in it, which > > >> are better handled by a full-fledged planner call backed up by the > > >> plan cache. If we don't do that then every evaluation of such > > >> "simple" expression needs to invoke the planner. For example: > > >> > > >> Consider this inline-able SQL function: > > >> > > >> create or replace function sql_incr(a bigint) > > >> returns int > > >> immutable language sql as $$ > > >> select a+1; > > >> $$; > > >> > > >> Then this revised body of your function foo(): > > >> > > >> CREATE OR REPLACE FUNCTION public.foo() > > >> RETURNS int > > >> LANGUAGE plpgsql > > >> IMMUTABLE > > >> AS $function$ > > >> declare i bigint = 0; > > >> begin > > >> while i < 1000000 > > >> loop > > >> i := sql_incr(i); > > >> end loop; return i; > > >> end; > > >> $function$ > > >> ; > > >> > > >> With HEAD `select foo()` finishes in 786 ms, whereas with the patch, > > >> it takes 5102 ms. > > >> > > >> I think the patch might be good idea to reduce the time to compute > > >> simple expressions in plpgsql, if we can address the above issue. > > > > > > > > > Your patch is very interesting - minimally it returns performance > before 8.2. The mentioned issue can be fixed if we disallow SQL functions > in this fast execution. > > > > I updated the patch to do that. > > > > With the new patch, `select foo()`, with inline-able sql_incr() in it, > > runs in 679 ms. > > > > Without any inline-able function, it runs in 330 ms, whereas with > > HEAD, it takes 590 ms. > > I polished it a bit. > the performance looks very interesting - on my comp the execution time of 100000000 iterations was decreased from 34 sec to 15 sec, So it is interesting speedup Pavel > Thanks, > Amit >
