Re: array_agg() on a set larger than some arbitrary(?) limit causes runaway memory usage and eventually memory exhaustion

* Frank van Vugt (ftm.van.vugt@foxi.nl) wrote:
> Op zaterdag 19 oktober 2013 21:02:25 schreef Valentine Gogichashvili:
> > this is a little bit not relevant to the question itself. But to preven=
t OOM
> > killer from currupting your database please consider this for your
> > production environments:
>=20
> Sure, I understand why you'd want to mention this 'on the side', but I'm =
aware=20
> of OOM-tuning. In production, I use it wherever it's _really_ needed, but=
 mind=20
> that the oom-killer in newer kernels is already selecting processes a bit=
=20
> smarter than it used to. In the example I gave, the correct child process=
 was=20
> killed.

The correct child being killed doesn't actually mean that it's a *good
idea* to kill off PG child processes, in general, particularly in the
way that the OOM killer goes about it (kill -9).  If it was possible to
tune the OOM killer to use a different signal, which would allow PG to
actually clean things up, it *might* be reasonable to allow it, but I
still wouldn't recommend it.

In production, for my part, proper memory accounting (and disabling of
OOM) should *always* be used.

    Thanks,

        Stephen