gnzsnz/upgrade_postgres_cluster.md

## upgrade_postgres_cluster.md

      
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              upgrade_postgres_cluster.md
            
          
    Install latest version
sudo apt install postgresql-16 postgresql-client-16
List clusters
sudo pg_lsclusters
output
Ver Cluster Port Status Owner    Data directory              Log file
15  main    5432 online postgres /var/lib/postgresql/15/main /var/log/postgresql/postgresql-15-main.log
16  main    5433 online postgres /var/lib/postgresql/16/main /var/log/postgresql/postgresql-16-main.log

drop the newly created cluster (which should be empty)
sudo pg_dropcluster 16 main --stop
verify
sudo pg_lsclusters
output
Ver Cluster Port Status Owner    Data directory              Log file
15  main    5432 online postgres /var/lib/postgresql/15/main /var/log/postgresql/postgresql-15-main.log

upgrade the existing cluster to the latest version
sudo pg_upgradecluster 15 main
verify
sudo pg_lsclusters
output
Ver Cluster Port Status Owner    Data directory              Log file
15  main    5433 down   postgres /var/lib/postgresql/15/main /var/log/postgresql/postgresql-15-main.log
16  main    5432 online postgres /var/lib/postgresql/16/main /var/log/postgresql/postgresql-16-main.log

drop old cluster
sudo pg_dropcluster 15 main
remove old version packages
sudo apt purge postgresql-15 postgresql-client-15
verify, cluster version 16 is up and running
sudo pg_lsclusters
Ver Cluster Port Status Owner    Data directory              Log file
16  main    5432 online postgres /var/lib/postgresql/16/main /var/log/postgresql/postgresql-16-main.log