| PostgreSQL upgrades are indeed one of the use cases we have with the gem, the way we do it is: 1. Have app configured to connect to both main and replica. 2. Connect to the rails console and tell the app to stay in read only mode until told otherwise. 3. Disable replication 4. Upgrade main to new PostgreSQL version 5. Tell the app to move back to read-write mode 6. Re-create the replica This flow helped us do hundreds of PostgreSQL major version upgrades in AWS RDS this quarter when we moved from PG 10 to 12. And this is just a plus, using the gem during normal operations means that if a Redis or PostgreSQL main explodes for any reason the app keeps serving traffic, albeit in read-only. > Automatic failover to the follower during this process would likely confuse things. I believe here the problem is mostly naming. The gem "failover" to read-only mode to a replica, it doesn't promote replicas to main ever. Naming is hard. |