Re: [RFC] obtaining the function call stack

On Jul 13, 2009, at 4:51 PM, decibel wrote:

> On Jul 13, 2009, at 2:33 PM, Tom Lane wrote:
>> Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
>>> Tom Lane wrote:
>>>> The performance and error recovery implications are unfavorable.
>>>> Just how badly do you need this, and for what?
>>
>>> Mainly for debugging. The situation is such that there is a lot of
>>> functions and very high load. The functions have embedded "debug
>>> elogs"
>>> and the intention is to call them only if the function was called
>>> in a
>>> particular context.
>>
>> I can't really see that as sufficiently widely useful to justify
>> inserting such a mechanism.
>>
>> I suspect also that you are defining the problem the wrong way ---
>> this
>> user doesn't want a generic fmgr call stack, he wants a plpgsql
>> stack.
>> Which is something the plpgsql debugger could be taught to do, if it
>> doesn't already, thus avoiding the overhead the 99.9% of the time
>> that
>> you don't need it.
>
> Actually, this could conceivably be called from other languages,
> such as plPerl.
>
> But it sounds like this can be done via an add-on, so no need to add
> it directly to the backend.

How would I go about generating a meaningful backtrace for a plpgsql
function that calls a plperl function? One would also expect a C
function which calls a plpgsql function to appear, too, no? Shouldn't
there be a unified backtrace subsystem?

Cheers,
M