> On Apr 30, 2024, at 8:20 AM, Ron Johnson <ronljohnsonjr@xxxxxxxxx> wrote: > > ZERO downtime is -- to my knowledge -- impossible with master-slave replication. There will always be some seconds of lag while the secondary-that-was is promoted to new-primary, and the applications that were forcibly disconnected from the old primary are connected to the new-primary. > > Heck, even in a master-master DB cluster, any connections on the master that dies will be down until they can connect to the other master. This is true. However, with a secondary that is up to date, and applications accessing through pgbouncer, client connections to pgbouncer are not broken, and pgbouncer connections to postgres can be reestablished quickly enough that users only observe a slightly slow response.
