pg_auto_failover is an extension for PostgreSQL that monitors and manages failover for a postgres clusters. It is optimised for simplicity and correctness.
Single Standby Architecture
pg_auto_failover architecture with a primary and a standby node
pg_auto_failover implements Business Continuity for your PostgreSQL services. pg_auto_failover implements a single PostgreSQL service using multiple nodes with automated failover, and automates PostgreSQL maintenance operations in a way that guarantees availability of the service to its users and applications.
To that end, pg_auto_failover uses three nodes (machines, servers) per PostgreSQL service:
- a PostgreSQL primary node,
- a PostgreSQL secondary node, using Synchronous Hot Standby,
- a pg_auto_failover Monitor node that acts both as a witness and an orchestrator.
The pg_auto_failover Monitor implements a state machine and relies on in-core PostgreSQL facilities to deliver HA. For example. when the secondary node is detected to be unavailable, or when its lag is reported above a defined threshold (the default is 1 WAL files, or 16MB, see the pgautofailover.promote_wal_log_threshold GUC on the pg_auto_failover monitor), then the Monitor removes it from the synchronous_standby_names setting on the primary node. Until the secondary is back to being monitored healthy, failover and switchover operations are not allowed, preventing data loss.
For this demo, we are going to be implementing the something like the architecture seen below
Multiple Standby Architecture
This blog is all about demonstrating the basic installation of pg_auto_failover.
If you want to read more about this, you can look at the documentation on the link below here
You can watch my demo below or click here to watch on YouTube and leave me a comment