For a software engineering project, you probably want to limit your transactions to much less than that (set statement_timeout is your friend). If you've got e

For a software engineering project, you probably want to limit your transactions to much less than that (set statement_timeout is your friend). If you've got extremely long transactions, you can probably avoid doing the switch-over when they run (hopefully they are not a random occurrence but a result of a scheduled job or similar). In combination with transaction time limit and fail-over configuration (where you fail the old primary), you can control the slowdown (instead of downtime, eg. with pgbouncer) very precisely. I would be more concerned with the DNS TTL being respected in the entire stack (and external caching DNS servers you rely on), tbh. But it is usually not critical to avoid a dozen seconds of downtime for an app, so whatever is simpler for you should be your go to solution.