Not sure if this is possible, but I’m looking to achieve zero downtime upgrades for our set of applications. We have a custom application that users use to connect to a set of services that transfer data on the backend to various Microsoft SQL databases. When we do software upgrades, the databases undergo various schema/table changes that cause application errors if you’re using the app while this maintenance is being done. I’m wondering if we’d be able to route users to use one SQL node that is not being upgraded while we upgrade the other SQL node’s databases, and merge changes from both nodes with zero or limited downtime so that we don’t have data loss for users that input the data or for the application update.
It seems like a stretch or perhaps a pipe dream but if anyone has any ideas I’m all ears!