Re: enhancing plpgsql debug api - hooks on statements errors and function errors

Hi

út 25. 4. 2023 v 10:27 odesílatel Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
napsal:

> Hi
>
> When I implemented profiler and coverage check to plpgsql_check I had to
> write a lot of hard maintaining code related to corect finishing some
> operations (counter incrementing) usually executed by stmt_end and func_end
> hooks. It is based on the fmgr hook and its own statement call stack. Can
> be nice if I can throw this code and use some nice buildin API.
>
> Can we enhance dbg API with two hooks stmt_end_err func_end_err ?
>
> These hooks can be called from exception handlers before re raising.
>
> Or we can define new hooks like executor hooks - stmt_exec and func_exec.
> In custom hooks the exception can be catched.
>
> What do you think about this proposal?
>
>
I did quick and ugly benchmark on worst case

CREATE OR REPLACE FUNCTION public.speedtest(i integer)
RETURNS void
LANGUAGE plpgsql
IMMUTABLE
AS $function$
declare c int = 0;
begin
while c < i
loop
c := c + 1;
end loop;
raise notice '%', c;
end;
$function$

and is possible to write some code (see ugly patch) without any performance
impacts if the hooks are not used. When hooks are active, then there is 7%
performance lost. It is not nice - but this is the worst case. The impact
on real code should be significantly lower

Regards

Pavel