This is a pretty normal way to handle things: double writes, active sync&#x2F;migration, double reads, disable old writes, finish sync, disable old reads.<p>Over the last 12 months we&#x27;ve migrated our entire system handling hundreds of millions of requests a day through 2 different database systems. Just requires testing and good release management.<p>Also it would be nice to have real numbers other than &quot;bajillions&quot;... what&#x27;s that even mean? Doesn&#x27;t sound like much more than a few gigs of data, in which case this transition could take seconds by just using an in-memory system.