This guide outlines the steps to upgrade a PostgreSQL server instance to a newer version using the pg_upgrade utility.
These instructions are written specifically for upgrading from PostgreSQL 10 to PostgreSQL 15.1. However, the upgrade process is generic and you should be able to swap out the version numbers for your use-case and still follow this how-to guide without a hiccup.
Additionally, this guide is for PostgreSQL servers on Red Hat Enterprise Linux / Cent OS / Oracle Linux – more generally known as the Red Hat family of Linux distros, but again, the process is similar for other Linux distributions – just replace RPM repository and package with the corresponding package repository and package name.
Customary Note: Always ensure that files and databases are backed up properly before performing an upgrade.
On that note, start by backing up the existing client authentication configuration file – pg_hba.conf (HBA stands for Host-based Authentication).
sudo cp /var/lib/pgsql/10/data/pg_hba.conf ~/pg_hba.conf.bakInstall the repository, install the newer version of PostgreSQL and initialize the database:
# Install the repository RPM:
sudo yum install -y https://download.postgresql.org/pub/repos/yum/reporpms/EL-7-x86_64/pgdg-redhat-repo-latest.noarch.rpm
# Install the newer version of PostgreSQL:
sudo yum install -y postgresql15-server
# Optionally initialize the database:
sudo /usr/pgsql-15/bin/postgresql-15-setup initdbChange to postgres user:
sudo su - postgresStop all connections from the application (or elsewhere) to the database in the older version of PostgreSQL:
/usr/pgsql-10/bin/pg_ctl -D /var/lib/pgsql/10/data -mf stopwaiting for server to shut down.... done server stopped
Use the pg_upgrade utility (from the new installation) to do a dry run and see if the new database cluster is compatible with the old one using the --check flag.
Make sure to specify the bin and data directories for the old and the new database clusters respectively:
/usr/pgsql-15/bin/pg_upgrade --old-bindir /usr/pgsql-10/bin --new-bindir /usr/pgsql-15/bin --old-datadir /var/lib/pgsql/10/data --new-datadir /var/lib/pgsql/15/data --link --checkPerforming Consistency Checks ----------------------------- Checking cluster versions ok Checking database user is the install user ok Checking database connection settings ok Checking for prepared transactions ok Checking for system-defined composite types in user tables ok Checking for reg* data types in user tables ok Checking for contrib/isn with bigint-passing mismatch ok Checking for user-defined encoding conversions ok Checking for user-defined postfix operators ok Checking for incompatible polymorphic functions ok Checking for tables WITH OIDS ok Checking for invalid "sql_identifier" user columns ok Checking for presence of required libraries ok Checking database user is the install user ok Checking for prepared transactions ok Checking for new cluster tablespace directories ok *Clusters are compatible*
If everything looks good, run the upgrade with the same command but without the --check flag.
/usr/pgsql-15/bin/pg_upgrade --old-bindir /usr/pgsql-10/bin --new-bindir /usr/pgsql-15/bin --old-datadir /var/lib/pgsql/10/data --new-datadir /var/lib/pgsql/15/data --linkPerforming Consistency Checks
-----------------------------
Checking cluster versions ok
Checking database user is the install user ok
Checking database connection settings ok
Checking for prepared transactions ok
Checking for system-defined composite types in user tables ok
Checking for reg* data types in user tables ok
Checking for contrib/isn with bigint-passing mismatch ok
Checking for user-defined encoding conversions ok
Checking for user-defined postfix operators ok
Checking for incompatible polymorphic functions ok
Checking for tables WITH OIDS ok
Checking for invalid "sql_identifier" user columns ok
Creating dump of global objects ok
Creating dump of database schemas
ok
Checking for presence of required libraries ok
Checking database user is the install user ok
Checking for prepared transactions ok
Checking for new cluster tablespace directories ok
If pg_upgrade fails after this point, you must re-initdb the
new cluster before continuing.
Performing Upgrade
------------------
Analyzing all rows in the new cluster ok
Freezing all rows in the new cluster ok
Deleting files from new pg_xact ok
Copying old pg_xact to new server ok
Setting oldest XID for new cluster ok
Setting next transaction ID and epoch for new cluster ok
Deleting files from new pg_multixact/offsets ok
Copying old pg_multixact/offsets to new server ok
Deleting files from new pg_multixact/members ok
Copying old pg_multixact/members to new server ok
Setting next multixact ID and offset for new cluster ok
Resetting WAL archives ok
Setting frozenxid and minmxid counters in new cluster ok
Restoring global objects in the new cluster ok
Restoring database schemas in the new cluster
ok
Adding ".old" suffix to old global/pg_control ok
If you want to start the old cluster, you will need to remove
the ".old" suffix from /var/lib/pgsql/10/data/global/pg_control.old.
Because "link" mode was used, the old cluster cannot be safely
started once the new cluster has been started.
Linking user relation files
ok
Setting next OID for new cluster ok
Sync data directory to disk ok
Creating script to delete old cluster ok
Checking for extension updates ok
Upgrade Complete
----------------
Optimizer statistics are not transferred by pg_upgrade.
Once you start the new server, consider running:
/usr/pgsql-15/bin/vacuumdb --all --analyze-in-stages
Running this script will delete the old cluster's data files:
./delete_old_cluster.sh
Exit out of the postgres user’s shell by employing one of these methods:
- Press
CTRL+D, or - Type
logoutand press Enter/Return key, or - Type
exitand press Enter/Return key
Enable and start the new PostgreSQL service:
sudo systemctl enable postgresql-15 sudo systemctl start postgresql-15Optionally, to check if the service is now running:
# optionally, to check
sudo systemctl status postgresql-15● postgresql-15.service - PostgreSQL 15 database server
Loaded: loaded (/usr/lib/systemd/system/postgresql-15.service; enabled; vendor preset: disabled)
Active: active (running) since Tue 2023-01-03 16:49:21 EST; 7s ago
Docs: https://www.postgresql.org/docs/15/static/
Process: 4482 ExecStartPre=/usr/pgsql-15/bin/postgresql-15-check-db-dir ${PGDATA} (code=exited, status=0/SUCCESS)
Main PID: 4488 (postmaster)
Tasks: 7
CGroup: /system.slice/postgresql-15.service
├─4488 /usr/pgsql-15/bin/postmaster -D /var/lib/pgsql/15/data/
├─4492 postgres: logger
├─4493 postgres: checkpointer
├─4494 postgres: background writer
├─4497 postgres: walwriter
├─4498 postgres: autovacuum launcher
└─4499 postgres: logical replication launcher
Jan 03 16:49:21 DA-WS-07 systemd[1]: Starting PostgreSQL 15 database server...
Jan 03 16:49:21 DA-WS-07 postmaster[4488]: 2023-01-03 16:49:21.136 EST [4488] LOG: redirecting log output to logging collector process
Jan 03 16:49:21 DA-WS-07 postmaster[4488]: 2023-01-03 16:49:21.136 EST [4488] HINT: Future log output will appear in directory "log".
Jan 03 16:49:21 DA-WS-07 systemd[1]: Started PostgreSQL 15 database server.
Once the service is started, change back to postgres user:
sudo su - postgres
Now, optimizer statistics can be generated with the vacuumdb utility (as they’re not transferred over by pg_upgrade utility):
# this could take a few minutes (especially when generating full optimizer statistics)
/usr/pgsql-15/bin/vacuumdb --all --analyze-in-stagesvacuumdb: processing database "test_db": Generating minimal optimizer statistics (1 target) vacuumdb: processing database "postgres": Generating minimal optimizer statistics (1 target) vacuumdb: processing database "template1": Generating minimal optimizer statistics (1 target) vacuumdb: processing database "test_db": Generating medium optimizer statistics (10 targets) vacuumdb: processing database "postgres": Generating medium optimizer statistics (10 targets) vacuumdb: processing database "template1": Generating medium optimizer statistics (10 targets) vacuumdb: processing database "test_db": Generating default (full) optimizer statistics vacuumdb: processing database "postgres": Generating default (full) optimizer statistics vacuumdb: processing database "template1": Generating default (full) optimizer statistics
At this point, you could restore the backed up pg_hba.conf file, or manually allow localhost to access the PostgreSQL database cluster over TCP by modifying the pg_hba.conf file:
vi /var/lib/pgsql/15/data/pg_hba.confComment the following lines (the hash or pound sign # indicates a commented line):
# "local" is for Unix domain socket connections only
# local all all peer
# IPv4 local connections:
# host all all 127.0.0.1/32 scram-sha-256
# IPv6 local connections:
# host all all ::1/128 scram-sha-256Add the following lines to the end of the file, replacing test_db with the name of your database and test_user with the name of your database user:
# Allow via TCP from localhost
host test_db test_user 127.0.0.1/32 md5
host test_db test_user ::1/32 md5Once again, exit out of the postgres user’s shell by employing one of these methods:
- Press
CTRL+D, or - Type
logoutand press Enter/Return key, or - Type
exitand press Enter/Return key
Restart the database service:
sudo systemctl restart postgresql-15Upgrade psql client by creating a symlink to the latest bundled version:
sudo ln -sf /usr/pgsql-15/bin/psql /usr/bin/psqlAt this point, the upgrade is complete and the everything should run normally.
Once database functionality is checked and verified for a successful upgrade, delete the old cluster’s data files by running the following as postgres user, if needed:
sudo su - postgres ./delete_old_cluster.shExit out of the postgres user shell for the final time. The upgrade is complete.