View source for Postgres master & slave

Login postgres
<syntaxhighlight lang=bash>
sudo -i -u postgres
psql
</syntaxhighlight>

Buat user & database
<syntaxhighlight lang=bash>
-- buat user
CREATE USER haidhi WITH PASSWORD 'supersecret';

-- kasih privilege
GRANT ALL PRIVILEGES ON DATABASE mydb TO haidhi;

-- buat database
CREATE DATABASE mydb OWNER haidhi;
</syntaxhighlight> 

Bikin replica
<syntaxhighlight lang=bash>
-- buat user replica
CREATE USER replicator REPLICATION LOGIN ENCRYPTED PASSWORD 'replicaPass';
ALTER ROLE replicator WITH REPLICATION;

-- konfirmasi 
\du replicator
</syntaxhighlight>

Edit config postgres di VM master 
<syntaxhighlight lang=bash>
sudo nano /etc/postgresql/15/main/postgresql.conf

# cari & ubah
listen_addresses = '*'
wal_level = replica
max_wal_senders = 10
wal_keep_size = 64
</syntaxhighlight>

Download Backup dari master (jalanin di slave)
<syntaxhighlight lang=bash>
sudo systemctl stop postgresql
sudo rm -rf /var/lib/postgresql/16/main/*
sudo chown -R postgres:postgres /var/lib/postgresql/16/main
sudo -i -u postgres
pg_basebackup -h <MASTER_IP> -D /var/lib/postgresql/16/main -U replicator -P --wal-method=stream
</syntaxhighlight>

Masih di slave, Harus ada entry primary_conninfo hasil dari <code>pg_basebackup -R</code>. Isinya kira² gini:
<syntaxhighlight lang=bash>
primary_conninfo = 'host=<MASTER_IP> port=5432 user=replicator password=replicaPass'
</syntaxhighlight>

Tambah di <code>/etc/postgresql/16/main/pg_hba.conf</code> master
<syntaxhighlight lang=bash>
# Replication access
host    replication    replicator    <SLAVE_IP>/32    md5
host    all            replicator    <SLAVE_IP>/32    md5
</syntaxhighlight>

Tambah di <code>/etc/postgresql/16/main/pg_hba.conf</code> slave
<syntaxhighlight lang=bash>
host    replication     replicator     < MASTER_IP>192.168.83.0/24         md5
</syntaxhighlight>

Cek di master
<syntaxhighlight lang=bash>
SELECT pid, client_addr, state, sync_state
FROM pg_stat_replication;
</syntaxhighlight>