Обсуждение: [HACKERS] proposal: enhanced stack trace for PL - print param args
Hi
In last discussion related to PLpgSQL was mentioned weak of stack trace PLpgSQL. The function parameters are not printed.
CREATE OR REPLACE FUNCTION public.foo(a double precision, b double precision)
RETURNS double precision
LANGUAGE plpgsql
AS $function$
begin
return 100/a;
end;
$function$
Current:
postgres=# select foo(0, 100);
ERROR: division by zero
CONTEXT: PL/pgSQL function foo(double precision) line 3 at RETURN
Proposed result:
postgres=# select foo(0, 100);
ERROR: division by zero
CONTEXT: PL/pgSQL function foo(double precision) line 3 at RETURN
ARGUMENTS: a=0, b=100
* only function parameters are printed - no local parameters
* the line of arguments will be limited - X chars ?
* the content of variable should be limited - X chars ? - maybe 40 chars
This function can has impact on performance - so it should be explicitly enabled with some GUC - like extra_back_trace or some similar. Probably before any call the function parameters and related out functions should be copied to safe memory context. More it can increase press on Error Memory Context and possibly on log size.
Is a interest about this feature? Comments, notes?
Regards
Pavel
On Sun, Jan 15, 2017 at 1:27 AM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
HiProposed result:postgres=# select foo(0, 100);ERROR: division by zeroCONTEXT: PL/pgSQL function foo(double precision) line 3 at RETURNARGUMENTS: a=0, b=100
+1 This would be useful in cases where an app calls one procedure and then disconnects. It's hard to know which of the thousands of invocations caused the error.
* only function parameters are printed - no local parameters
+1, we'd have no insight into variables inside the function anyway.
* the line of arguments will be limited - X chars ?
+1
* the content of variable should be limited - X chars ? - maybe 40 charsThis function can has impact on performance - so it should be explicitly enabled with some GUC - like extra_back_trace or some similar. Probably before any call the function parameters and related out functions should be copied to safe memory context. More it can increase press on Error Memory Context and possibly on log size.
func_args_back_trace?