st 19. 2. 2020 v 7:30 odesílatel Pavel Stehule <pavel.steh...@gmail.com> napsal:
> > > 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 > but regress tests fails > Pavel > > > >> Thanks, >> Amit >> >
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