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

Hi

út 25. 4. 2023 v 10:27 odesílatel Pavel Stehule <pavel.stehule@gmail.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