On Tue, Jun 21, 2016 at 08:19:55AM -0400, Robert Haas wrote: > On Mon, Jun 20, 2016 at 10:08 PM, Bruce Momjian <br...@momjian.us> wrote: > >> No, not really. Once you let write transactions into the new cluster, > >> there's no way to get back to the old server version no matter which > >> option you used. > > > > Yes, there is, and it is documented: > > > > If you ran <command>pg_upgrade</command> <emphasis>without</> > > <option>--link</> or did not start the new server, the > > old cluster was not modified except that, if linking > > started, a <literal>.old</> suffix was appended to > > <filename>$PGDATA/global/pg_control</>. To reuse the old > > cluster, possibly remove the <filename>.old</> suffix from > > <filename>$PGDATA/global/pg_control</>; you can then restart the > > old cluster. > > > > What is confusing you? > > I don't think I'm confused. Sure, you can do that, but the effects of > any writes performed on the new cluster will not be there when you > revert back to the old cluster. So you will have effectively lost > data, unless you somehow have the ability to re-apply all of those > write transactions somehow.
Yes, that is true. I assume _revert_ means something really bad happened and you don't want those writes because they are somehow corrupt. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Ancient Roman grave inscription + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
