How to upgrade postgresql database from 10 to 12 without losing data for openproject

A) First create a backup of all the databases for that (You can continue from B if you dont need a backup)

1. Log in as postgres user

    sudo su postgres

2. Create a backup .sql file for all the data you have in all the databases

    pg_dumpall > backup.sql

B) Upgrade to PostgreSQL12

1. update packages and install postgres 12

     sudo apt-get update
     sudo apt-get install postgresql-12 postgresql-server-dev-12

2. Stop the postgresql service

     sudo systemctl stop postgresql.service

3. migrate the data

     /usr/lib/postgresql/12/bin/pg_upgrade \
     --old-datadir=/var/lib/postgresql/10/main \
     --new-datadir=/var/lib/postgresql/12/main \
     --old-bindir=/usr/lib/postgresql/10/bin \
     --new-bindir=/usr/lib/postgresql/12/bin \
     --old-options '-c config_file=/etc/postgresql/10/main/postgresql.conf' \
     --new-options '-c config_file=/etc/postgresql/12/main/postgresql.conf'

4. Switch to regular user

     exit

5. Swap the ports the old and new postgres versions.

     sudo vim /etc/postgresql/12/main/postgresql.conf
     #change port to 5432
     sudo vim /etc/postgresql/10/main/postgresql.conf
     #change port to 5433

6. Start the postgresql service

     sudo systemctl start postgresql.service

7. Log in as postgres user

     sudo su postgres

8. Check your new postgres version

     psql -c "SELECT version();"

8. Run the generated new cluster script

     ./analyze_new_cluster.sh

9. Return as a normal(default user) user and cleanup up the old version's mess

     sudo apt-get remove postgresql-10 postgresql-server-dev-10
     #uninstalls postgres packages
     sudo rm -rf /etc/postgresql/10/
     #removes the old postgresql directory
     sudo su postgres
     #login as postgres user
     ./delete_old_cluster.sh
     #delete the old cluster data

10. Congrads! Your postgresql version is now upgraded, If everything works well in B, we dont have to apply the backup as we have already migrated the data from the older version to the newer version, the backup is just in case if anything goes wrong.

NOTE: Change the postgresql.conf and pg_hba.conf as per your requirement

PS: Feel free to comment your issues, suggestions or anyother modifications you would like to suggest

1. Backup the database
   

   psql --version sudo -u postgres psql pg_dumpall > alldbs.sql
   

   (this command will backup all databases from the postgresql db)

Then exit from postgres user, and:

2. Inside a terminal run these commands:

   sudo systemctl stop postgres
   sudo apt-get install -y postgresql-12 postgresql-server-dev-12 postgresql-contrib-12 libpq-dev postgresql-12-hypopg
   sudo pg_dropcluster 12 main --stop
   sudo pg_upgradecluster 10 main
   sudo pg_dropcluster 10 main --stop
   

3. restart the postgresql service:

   sudo systemctl restart postgresql
   

4. login to the postgres:

   su - postgres
   

5. to check the version:

   psql --version
   

I have done using the above steps and I could update the DBand restore all data.