Re: server crash on recursive function invocation

hi,
i was just trying recursive function invocation and got a server crash when i changed a GUC variable max_stack_depth, to a high number.
fallowing is what i have tried.

select max_val from pg_settings where name='max_stack_depth'; -- returns 2097151
set max_stack_depth=2097151;
CREATE OR REPLACE FUNCTION func() RETURNS INT AS $$
DECLARE
x int;
BEGIN
null;
x := func();
return 0;
END;
$$ LANGUAGE PLPGSQL;
select func();
and the server get crashed.

Any ideas?

Thanks,
--Usman

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Ali Baba said:
>
> hi,
> i was just trying recursive function invocation and got a server crash
> when i changed a GUC variable max_stack_depth, to a high number.
> fallowing is what i have tried.
>
> select max_val from pg_settings where name='max_stack_depth'; --
> returns 2097151 set max_stack_depth=2097151;
> CREATE OR REPLACE FUNCTION func() RETURNS INT AS $$
> DECLARE
> x int;
> BEGIN
> null;
> x := func();
> return 0;
> END;
> $$ LANGUAGE PLPGSQL;
> select func();
> and the server get crashed.
>
>
> Any ideas?
>

what the heck did you expect with an infinitely recursive function?

cheers

andrew

Ali Baba <idofyear(at)yahoo(dot)com> writes:
> i was just trying recursive function invocation and got a server crash when i changed a GUC variable max_stack_depth, to a high number.

There's a reason why that variable is a superuser-only setting: you're
supposed to have some clue what you're doing when you change it ;-)

If you need more stack space, what you generally have to do is adjust
the ulimit setting that the postmaster is started under. You can set
max_stack_depth up to a few hundred K less than the postmaster's
ulimit -s setting, but not more.

(We wouldn't even have the variable if there were a sufficiently
portable way to find out the ulimit stack depth automatically, but
there's not one that I know of.)

regards, tom lane