Re: pg_upgrade and rsync

On 2015-01-27 10:20:48 -0500, Robert Haas wrote:
> On Tue, Jan 27, 2015 at 9:50 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > Robert Haas <robertmhaas@gmail.com> writes:
> >> On Fri, Jan 23, 2015 at 1:48 PM, Andres Freund <andres@2ndquadrant.com> wrote:
> >>> I don't understand why that'd be better than simply fixing (yes, that's
> >>> imo the correct term) pg_upgrade to retain relfilenodes across the
> >>> upgrade. Afaics there's no conflict risk and it'd make the clusters much
> >>> more similar, which would be good; independent of rsyncing standbys.
> >
> >> +1.
> >
> > That's certainly impossible for the system catalogs, which means you
> > have to be able to deal with relfilenode discrepancies for them, which
> > means that maintaining the same relfilenodes for user tables is of
> > dubious value.
> 
> Why is that impossible for the system catalogs?

Maybe it's not impossible for existing catalogs, but it's certainly
complicated. But I don't think it's all that desirable anyway - they're
not the same relation after the pg_upgrade anyway (initdb/pg_dump
filled them). That's different for the user defined relations.

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
Services