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How to setup Streaming Replication in PostgreSQL 13
What has changed in 13
Things have changed in PostgreSQL 13. If you’re used to replication PostgreSQL instances prior to 13 you will see that the setup is cleaner now. It’s also easier to start the replication process by creating the base backup. Let’s go through the important bits:
On the primary server you do nothing outside of making it accesible from the secondary server. In order to do that you will have to change the listen_address
listen_addresses = '*'
Then on the secondary server’s
postgresql.conf
file add information about the primary:
primary_conninfo = 'host=22.80.27.199 port=5432'
by specifying the IP address and the port.
If you’re running a firewall such as UFW on the primary you will have to ensure you can connect to the primary from the secondary.
You can verify the connection using telnet
telnet 22.80.27.199 5432
If your firewall is blocking access then open it up to the secondary by running the following on the primary
sudo ufw allow from 22.80.27.198 to any port 5432
If everything connects then you can create the base backup which will prime the secondary for replication
su postgres
As the postgres user execute
touch /var/lib/postgresql/13/main/standby.signal
to signal for this machine to be the standby and then
pg_basebackup -h 22.80.27.199 -U postgres -p 5432 -D $PGDATA -Fp -Xs -P -R
to start the base backup. And that’s it. You should now be able to verify the lag between the primary and the secondary via psql console
su postgres
psql
select now()-pg_last_xact_replay_timestamp() as replication_lag;
