Обсуждение: Cloning databases using rsync

I regularly copy all my postgresql data onto another computer and access
it locally there.  This works if I use pg_dump, transfer the output
file, and feed that file into psql.  However, I would prefer  to copy
the databases using rsync instead of pg_dump, because it's simpler and
faster.  (I know the server has to be down to avoid corruption.)

    rsync -avx --delete 132.205.86.95:/var/lib/postgresql /var/lib

After doing this, when I run psql I get

    psql: FATAL:  database "xxxxx", OID 12345, has disappeared from
pg_database

where "xxxxx" and 12345 depend on the database.  /var/lib/postgresql is
identical on both systems, and so is /etc/postgresql other than
host-specific things like IP addresses.  The version is the same (8.0).
The directory "12345" exists.  Any ideas of what else might have to be
copied?

David

David Gaudine <davidg@alcor.concordia.ca> writes:
> I regularly copy all my postgresql data onto another computer and access
> it locally there.  This works if I use pg_dump, transfer the output
> file, and feed that file into psql.  However, I would prefer  to copy
> the databases using rsync instead of pg_dump, because it's simpler and
> faster.  (I know the server has to be down to avoid corruption.)

This should work as long as both machines are identical processor
architectures and have identical Postgres versions compiled with
identical options.  (Note that 8.1 tries harder than previous versions
to detect option mismatch during server startup, but I wouldn't swear
that it's bulletproof either.)  I suspect you've broken one of these
rules.

            regards, tom lane

Tom Lane wrote:

>This should work as long as both machines are identical processor
>architectures and have identical Postgres versions compiled with
>identical options.  (Note that 8.1 tries harder than previous versions
>to detect option mismatch during server startup, but I wouldn't swear
>that it's bulletproof either.)  I suspect you've broken one of these
>rules.
>
>

That encouraged me to try again.  I previously claimed that /etc/postgresql
was the same on both systems (except stuff like IP addresses),
but to make sure I used rsync to copy /etc/postgresql to the second system.
Now it works, so I must have missed something in there, although I still
can't see any difference.
David