Replicate specific tables to another PostgreSQL instance with logical replication (publication/subscription)

Documented steps

1. On the publisher, set wal_level = logical in postgresql.conf and restart the server.
2. Make sure each published table has a primary key, or set a replica identity for UPDATE/DELETE replication: ALTER TABLE t REPLICA IDENTITY USING INDEX <unique_index>; or ALTER TABLE t REPLICA IDENTITY FULL; (slower).
3. Create the publication on the publisher: CREATE PUBLICATION pub1 FOR TABLE table1, table2;
4. Create matching tables on the subscriber (schema is NOT replicated), then: CREATE SUBSCRIPTION sub1 CONNECTION 'host=publisher dbname=src user=repl' PUBLICATION pub1; (supply the replication role's credential via standard libpq mechanisms such as a ~/.pgpass file rather than inline) — this creates a replication slot on the publisher, copies initial data, then streams changes.
5. Monitor: on the subscriber SELECT * FROM pg_stat_subscription; and SELECT srrelid::regclass, srsubstate FROM pg_subscription_rel; (state 'r' = ready/synced). On the publisher: SELECT slot_name, restart_lsn, confirmed_flush_lsn FROM pg_replication_slots;
6. Official docs: https://www.postgresql.org/docs/current/logical-replication.html and https://www.postgresql.org/docs/current/logical-replication-restrictions.html