Re: plan cache overhead on plpgsql expression

ne 16. 2. 2020 v 15:12 odesílatel Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
napsal:

> Hi
>
> when I do some profiling of plpgsql, usually I surprised how significant
> overhead has expression execution. Any calculations are very slow.
>
> This is not typical example of plpgsql, but it shows cleanly where is a
> overhead
>
> CREATE OR REPLACE FUNCTION public.foo()
> RETURNS void
> LANGUAGE plpgsql
> IMMUTABLE
> AS $function$
> declare i bigint = 0;
> begin
> while i < 100000000
> loop
> i := i + 1;
> end loop;
> end;
> $function$
>
>
> Is interesting so overhead of plan cache about 15%
>
> The execution needs 32 sec on Postgres13 and 27sec on Postgres8.2
>

On same computer same example in Perl needs only 7 sec.

Regards

Pavel

> Regards
>
> Pavel
>
>