PostgreSQL 12 High Availability Cookbook - Third Edition

Testing the waters

Several repmgr commands also accept the --dry-run argument. When supplied to an operation, repmgr will invoke the process normally, but will only produce debugging output, and will skip elements that would modify the cluster state. It's a way of verifying that there are no unexpected problems that would definitely disrupt the switchover.

This is especially important here, as a switchover actually performs several actions:

• Stops the current primary node
• Promotes the standby on the selected node
• Converts the old primary into a new standby
• Connects to any other nodes in the cluster and changes their streaming connection

This is not an exhaustive list, as each of the preceding steps may consist of further granular operations. ...