Re: doc: expand note about pg_upgrade's --jobs option

On Wed, Mar 5, 2025 at 5:28 PM Nathan Bossart <nathandbossart@gmail.com>
wrote:

> On Wed, Mar 05, 2025 at 09:35:27AM -0600, Nathan Bossart wrote:
> > On Wed, Mar 05, 2025 at 01:52:40PM +0100, Magnus Hagander wrote:
> >> Another option that I think would also work is to just cut down the
> details
> >> to just "The <option>--jobs</option> option allows multiple CPU cores
> to be
> >> used".
> >
> > That's fine with me.  It's probably not particularly actionable
> > information, anyway.  If anything, IMHO we should make it clear to users
> > that the parallelization is per-database (except for file transfer, which
> > is per-tablespace).  If you've just got one big database in the default
> > tablespace, --jobs won't help.
> >
> >> I think this is also slightly confusing, but maybe that's a
> >> non-native-english thing: "a good place to start is the maximum of the
> >> number of  CPU cores and tablespaces.". Am I supposed to set it to
> >> max(cpucores, ntablespaces) or to max(cpucores+ntablespaces)?
> >
> > I've always read it to mean the former.  But I'm not sure that's great
> > advice.  If you have 8 cores and 100 tablespaces, does it make sense to
> use
> > --jobs=100?  Ordinarily, I'd suggest the number of cores as the starting
> > point.
>
> Here's another attempt at the patch based on the latest discussion.
>

LGTM!

-- 
 Magnus Hagander
 Me: https://www.hagander.net/ <http://www.hagander.net/>
 Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>