Postgres Streaming Replication: 30-Minute Tutorial

Replication is the foundation of Postgres HA. Setup is fewer steps than people expect.

Step 1: Configure primary

Edit primary’s postgresql.conf: wal_level = replica, max_wal_senders = 10.

Restart primary.

Step 2: Take base backup

• pg_basebackup -h primary -D /var/lib/pgsql/data -P -U replicator
• Creates a clone of primary’s data.

Step 3: Start replica

Replica’s postgresql.conf set as standby (recovery.conf or signal file in PG12+).

Start replica; it streams from primary.

Step 4: Verify replication

On primary: SELECT * FROM pg_stat_replication; shows the replica.

On replica: read-only queries; cannot write.

Antipatterns

• Replica with no monitoring. Lag undetected.
• Manual failover only. Practice or use Patroni.
• Replica writes. Will not work; data drift if forced.

What to do this week

Three moves. (1) Run the tutorial end-to-end on your own laptop / sandbox. (2) Apply the pattern to one production workload. (3) Document the variations you needed; share with the team.