How to Automate PostgreSQL 12 Replication and Failover with repmgr

A replication slot ensures that the needed WAL files for the standby are not removed in the primary server before the standby server processes

Replication slots are used to safeguard against the premature deletion of WAL segments before they have been applied by the standby server, thus

replication slot already exists In this case the slot is called pg_basebackup_N where N is the PID of the backend process running the replication connection However there

replication slot does not exist Although when a connector is not active, Postgres may allow other connector to consume the replication slot