I'm upgrading from postgres 8.4 to 9.0 and looking at the manual it looks like this is my only choice:
pg_dumpall -p 5432 | psql -d postgres -p 6543
Which means I'll need to stop any writes to the database and wait whilst a couple of gb's of data is transferred.
Is there a better way in which I can use the Write Ahead Log (WAL) to replay any new SQL onto the new database?