Upgrade Postgresql From 14 to 15

Date: 2023/12/03
Last Updated: 2024-06-05T11:18:36.167Z
Categories: Postgresql, Database
Tags: Postgresql, Database
Read Time: 2 minutes

Recently, I have upgraded my Postgresql database for my freshrss instance from 14 to 15. Here are the steps I followed to do it.

First, we need to local the binary of the old version of Postgresql. In most of the cases, it can be found by

which psql

In my case, it is /usr/local/bin/psql.

Then, we need to find the data directory of the old version of Postgresql. In my case, it is at /var/lib/postgres/14. And the postgresql.conf file is at /var/lib/postgres/14/data/postgresql.conf.

Then, we need to install the new version of Postgresql. I use nix to manage my packages, so I just change the version of Postgresql in my configuration.nix file and run nixos-rebuild switch.

After that, we need to find the binary of the new version of Postgresql. Which can be found by

which psql

Then, we need to find the data directory of the new version of Postgresql. In my case, it is at /var/lib/postgres/15. And the postgresql.conf file is which you should copy and modify from the old version of Postgresql.

We need to first stop the old version of Postgresql.

systemctl stop postgresql

And su to the postgres user.

sudo su - postgres

Then, we need to run the following command to first initialize the new version of Postgresql.

initdb -D /var/lib/postgres/15/

Then, we need

Then, we need to run the following command to migrate the data from the old version of Postgresql to the new version of Postgresql. With --check option, it will check if the migration is possible.

/usr/lib/postgresql/15/bin/pg_upgrade \
  --old-datadir=$OLD_DATADIR \
  --new-datadir=$NEW_DATADIR \
  --old-bindir=$OLD_BINDOR \
  --new-bindir=$NEW_BINDIR \
  --old-options '-c config_file=$OLD_CONFIG_FILE' \
  --new-options '-c config_file=$NEW_CONFIG_FILE' \
  --check

If the check is successful, we can run the following command to do the migration.

/usr/lib/postgresql/15/bin/pg_upgrade \
  --old-datadir=$OLD_DATADIR \
  --new-datadir=$NEW_DATADIR \
  --old-bindir=$OLD_BINDOR \
  --new-bindir=$NEW_BINDIR \
  --old-options '-c config_file=$OLD_CONFIG_FILE' \
  --new-options '-c config_file=$NEW_CONFIG_FILE'

After that, we need to check if the migration is successful. If it is successful, we can then remove the old version of Postgresql.