upgrading from 8.1.4 to 8.3.3

Hello all,

I'm getting this error after installing pg-8.3.3 on a test system which
had 8.1.4

shell> su postgres -c "/usr/bin/postmaster -D /var/pgsql/data"
FATAL:  database files are incompatible with server
DETAIL:  The data directory was initialized by PostgreSQL version 8.1,
which is not compatible with this version 8.3.3.


I guess I should get a pg_dumpall before upgrading and put the data back
after the upgrade.

Is this correct ?

Is there a more apropriate approach ?

thanks
joao