There are various ways to 'pause' incoming postgres queries, for example using pgbouncer, - ie. don't fail them, simply delay them until the replication has cau

There are various ways to 'pause' incoming postgres queries, for example using pgbouncer, - ie. don't fail them, simply delay them until the replication has caught up and then let them continue on the new database. If anything goes wrong and replication doesn't catch up, you can unpause and let those queries happen on the old database. Therefore, your 11 seconds of downtime becomes 0 to 11 seconds of added page load time. But more importantly, of the thousands of users of the database who have never seen a query fail before and might have buggy error handling codepaths or have a single failed query ruin a whole batch job, this approach leads to a lot less collateral damage.