On 13/11/2020 18:10, Alexey Bashtanov wrote:
> Hi,
>
> I got somewhat scared when my explain took a few seconds to complete and
> used a few gigs of RAM.
> To reproduce try the following:
>
> discard temp;
> create temp table a as select to_timestamp(generate_series(1, 7000)) i;
> analyze a;
> set work_mem to '3GB';
> explain select distinct a1.i - a2.i from a a1, a a2;
>
> I would appreciate if someone could have a look at the patch attached,
> which makes executor skip initializing hash tables when doing explain only.
Makes sense. Committed, thanks for the patch!
- Heikki
