Upgrade Postgresql 8.3 database file to 8.4 - postgresql

Question

I upgraded my Ubuntu 8.04 To Ubuntu 10.04. Unfortunately, the upgrade process also updated the Postgres 8.3 install to a Postgres 8.4 install. My feeling is that although database engine binaries have been updated, the database itself was not migrated, hence it can not be loaded by the 8.4.
Since the 8.3 data format is not compatible with 8.4 format, altering postgresql.conf is not enough, nor can I use pg_dump with my 8.4 install.
I need a way to upgrade my previous base from 8.3 to 8.4, with no access to a 8.3 engine, only a 8.4.
Any clue?

Answer 1

The postgres packages in Debian, and hence, Ubuntu, has a very clearly defined way of upgrading from one Postgres version to another. The procedure is documented in /usr/share/doc/postgresql-common/README.Debian as follows:
Default clusters and upgrading
------------------------------
When installing a postgresql-X.Y package from scratch, a default
cluster 'main' will automatically be created. This operation is
equivalent to doing 'pg_createcluster X.Y main --start'.
Due to this default cluster, an immediate attempt to upgrade an
earlier 'main' cluster to a new version will fail and you need to
remove the newer default cluster first. E. g., if you have
postgresql-8.2 installed and want to upgrade to 8.3, you first install
postgresql-8.3:
apt-get install postgresql-8.3
Then drop the default 8.3 cluster:
pg_dropcluster 8.3 main --stop
And then upgrade the 8.2 cluster to 8.3:
pg_upgradecluster 8.2 main
The best time to do this is before ugrading to a version of Ubuntu where the version of Postgresql you're currently running has been removed, i.e. in this example, while on a version of Ubuntu that has the possibility to install both Postgres 8.3 and Postgres 8.4. In my case, I went from jaunty to karmic, upgraded 8.3 to 8.4 and then went from karmic to lucid.
The upgrade process as described above is very smooth. The *pg_upgradecluster* command will stop the old version, migrate data, then start the new version on the same port as the old version, finally starting the old version on a new port.
If you did not migrate your 8.3 postgres data before moving to an Ubuntu version that lacks postgres 8.3, migrating is still simple. Start by adding the karmic ubuntu repository to /etc/apt/sources.list:
deb http://archive.ubuntu.com/ubuntu/ karmic main restricted universe
Install postgresql-8.3:
apt-get update && apt-get install postgresql-8.3
Drop your 8.4 cluster. Warning: This will remove data in your postgresql 8.4 installation if you have any. But if you're only doing this because you need to upgrade your 8.3 to 8.4, you will have no data in your 8.4 cluster.
pg_dropcluster 8.4 main --stop
And then upgrade the 8.3 cluster to 8.4:
pg_upgradecluster 8.3 main
Finally, remove the postgresql-8.3 package, and remove the jaunty-line from /etc/apt/sources.list, then run apt-get update again.
As usual, taking a backup of your postgres directories before doing any of the above is always a good idea.

Answer 2

You'll have to install PostgreSQL 8.3 in temporary location from source, copy your old data there, start Pg, dump it's data using pd_dumpall and then import this data to new Postgres.
It's impossible without installing Pg 8.3.

Answer 3

Make sure you backup everything before you try anything.
There is the pg_migrator project which I think will do that for you, though I'm not sure whether it needs to 8.3 applications or source code.