Re: BUG #16976: server crash when deleting via a trigger on a foreign table

Hi Support,


The problem is  in ifx_fdw.c but I do not have dbg packages installed 
for this nor do I know where to find these for ubuntu.

But is there no way you can simulate this issue ? There is a PG server 
crash due to bad user code in a trigger function.

In the mean time we found out that the user code in the trigger function 
was wrong: it has to work with old instead of new values:

      delete from informix.t_water_eenheid

                 where enh_id = old.enh_id;

                 return old;

instead of:


                 delete from informix.t_water_eenheid

                 where enh_id = new.enh_id;

                 return new;

using old it works fine.

But regardless, the PG server should not crash due to bad user code. I 
suppose you agree.

I only work 2 days a week for this client and this is taking up much of 
my time so I was hoping you could simulate this.



Kind regards,



Herwig



On 23/04/2021 00:45, Thomas Munro wrote:
> On Thu, Apr 22, 2021 at 10:09 PM Herwig Goemans
> <herwig.goemans@gmail.com> wrote:
>> And I cannot execute anything in the attached (psql) process,
> A couple of notes about the attach-then-crash approach:  It should be
> "postgres", not "psql", that you attach to, and then you need to type
> "cont" to tell the debugger to allow execution to continue, or it'll
> just block as you described. Sometimes it will stop execution when
> signals arrive, and you can disable that with eg "handle SIGUSR1
> nostop" and then go back to executing with "cont" again.  Once you
> make it crash, you'll be able to use "bt" to see exactly where, but as
> mentioned it'll just be a bunch of big hex numbers unless the symbols
> are installed; at the least it'll show which modules (postgres,
> informix_fdw.so or such).