Re: BUG #19105: Parallel Hash Join crash when work_mem is small

On 11/9/25 16:47, Tom Lane wrote:
> PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
>> PostgreSQL version: 16.2
>
>> Server terminates with:
>
>> ERROR: could not attach to dynamic shared area
>> DETAIL: invalid dsa_handle
>
> I could not reproduce this problem with current sources
> (either master or v16 branch tip). 16.2 is pretty old,
> so maybe an update will fix it for you.
>

FWIW I couldn't reproduce it on 16.2 either, even after forcing it to
actually do parallel hash join (the posted instructions were not enough
to make that happen on my system).

Presumably there's some additional detail making it fail, but there are
too many options to guess. Maybe it's some kernel limit, something in
ubuntu 22.04, or something else.

It's interesting the report claims this happens only "when work_mem is
small". I wonder if that happens simply because the plan changes.

regards

--
Tomas Vondra