===== PostgreSQL Upgrades =====

==== Using pg_upgrade ====
https://www.postgresql.org/docs/14/pgupgrade.html

<code bash>
/usr/lib/postgresql/14/bin/pg_upgrade   --old-datadir=/var/lib/postgresql/10/main   
                                        --new-datadir=/var/lib/postgresql/14/main   
                                        --old-bindir=/usr/lib/postgresql/10/bin   
                                        --new-bindir=/usr/lib/postgresql/14/bin   
                                        --old-options='-c config_file=/etc/postgresql/10/main/postgresql.conf'   
                                        --new-options='-c config_file=/etc/postgresql/14/main/postgresql.conf'   
                                        --link --jobs=4 --check
</code>

Upgrade Streaming Replication server. \\
<code bash>
rsync --verbose --archive --delete --hard-links --size-only --no-inc-recursive --human-readable 
      10 14 postgres@postgres02-upgrade:/var/lib/postgresql
</code>

==== Using pg_dumpall ====
https://www.postgresql.org/docs/14/upgrading.html#UPGRADING-VIA-PGDUMPALL

If necessary, create a new instance … \\
<code bash>
pg_createcluster -d /var/lib/postgresql/14/doob 14 doob
</code>

On postgres-test, this used port 5434 for the new instance. \\
Copy the pg_hba.conf and postgresql.conf files from the old instance to the new one … \\
<code bash>
cp /var/lib/postgresql/10/main/postgresql.conf /var/lib/postgresql/14/doob
cp /var/lib/postgresql/10/main/pg_hba.conf /var/lib/postgresql/14/doob
</code>

Edit the postgresql.conf and update relevant entries to 14/doob. \\
Restart the new PostgreSQL 14 instance … \\
<code bash>
sudo systemctl restart postgresql@14-doob
</code>

Copy data from the old instance to the new using the following command … \\
<code bash>
pg_dumpall -p 5432 -U postgres -d postgres | psql -p 5434 -U postgres -d postgres
</code>

If you wish to test the above process again then delete the cluster and begin again from the start … \\
<code bash>
pg_dropcluster 14 doob --stop
</code>
Otherwise, stop the old instance and then configure the new instance to use port 5432 and restart.