Preserve WALs on promoted node in PostgreSQL 14

Question

I have PostgreSQL streaming replication setup using replication slot. Node1 is primary and Node2 is slave. Now, node1 is down and promoted node2. Node2 is running and in read-write mode. There is heavy load on node2 now. How i can make sure enough WALs getting preserved on node2, so that when node1 joins, it could do diff sync using pg_rewind. This is PostgreSQL 14. There is no WAL archiving setup.

Answer 1

For that, you'd have to create a replication slot on Node2 during failover:

SELECT pg_create_physical_replication_slot(
          slot_name => 'slot',
          immediately_reserve => TRUE
       );