PostgreSQL 12 High Availability Cookbook - Third Edition

How to do it...

For the purposes of this recipe, pgha2 will be our primary node, and the old primary will be pgha1. Follow these steps to reincorporate pgha1 into the repmgr cluster:

1. If this wasn't a planned switchover event, check the PostgreSQL logs for any anomalies that could explain the outage. Likewise, gather forensic and diagnostic evidence, as this information will likely be destroyed once the node is reintroduced to the cluster.
2. If it is not already stopped, stop PostgreSQL on pgha1 with this command on Debian-based systems:

sudo systemctl stop postgresql@12-main

Red Hat variants should use this command instead:

sudo systemctl stop postgresql-12

3. Issue the following command on pgha1 as postgres to test the rejoin process:

repmgr ...