Re: Speeding up pg_upgrade

Stephen Frost <sfrost@snowman.net> writes:
> If we go down that route, since this makes a pretty serious difference
> in terms of what the user has to deal with post-pg_upgrade, I'd suggest
> we require an additional option for the user to pass when stats aren't
> going to be migrated, so they are aware of that.

-1 ... you are forgetting that a lot of systems wrap pg_upgrade in some
sort of vendor-supplied upgrade script.  Nanny switches don't help;
the vendors will just start passing them automatically.

> Of course, this might end up having an entirely different effect: it
> might mean that we're suddenly a lot shier about changing the stats in a
> backwards-incompatible way, just as we now are basically stuck with the
> existing on-disk heap format..

Yeah, there's that.  But the rate of change in pg_statistic hasn't been
*that* large.  Alvaro might be right that we can design some transmission
procedure that allows stats to be forward-migrated when compatible and
dropped when not.

            regards, tom lane