I'm working on a setup where I have a duplicate server at a remote location that is rsynced every night with the primary server. Both servers are self hosted. The intention is that if the primary server goes down for some reason (internet failure etc) the secondary could be spun up fairly quickly to take over. But, I'm concerned about the scenario where transactions and content that has been changed on the primary between the time of the last backup and the failure will be left in limbo. Is there a good way to merge the two databases when it's time to switch back to the primary?