PostgreSQL 12 High Availability Cookbook - Third Edition

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The reason preventing split brain is so difficult is that it's not an easy problem to solve. This is why dedicated software for managing high availability exists. While these are not immune to the issue, they greatly reduce the potential of occurrence.

Pacemaker has components specifically for interacting with STONITH hardware. repmgr implements the concept of hook scripts for event notifications, and accounts for scenarios where the Primary is isolated from the remainder of the cluster as seen in the previous diagram. Patroni uses a sophisticated locking mechanism that only allows one primary node to be registered at once.

Don't try to invent a solution for an already solved problem when most of the work has already been ...