Re: Parallel threads in query

On Wed, Oct 31, 2018 at 2:11 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> =?UTF-8?Q?Darafei_=22Kom=D1=8Fpa=22_Praliaskouski?= <me(at)komzpa(dot)net>
> writes:
> > Question is, what's the best policy to allocate cores so we can play nice
> > with rest of postgres?
>

> There is not, because we do not use or support multiple threads inside
> a Postgres backend, and have no intention of doing so any time soon.
>

As a practical matter though, if we're multi-threading a heavy PostGIS
function, presumably simply grabbing *every* core is not a recommended or
friendly practice. My finger-in-the-wind guess would be that the value
of max_parallel_workers_per_gather would be the most reasonable value to
use to limit the number of cores a parallel PostGIS function should use.
Does that make sense?

P