I never understood which table caused these issues at Uber. They use an example with birthday changes for users. That's no real world example. Apparently issues were caused by a small table updated 500+ times a second and used in a lot of joins. That could be the driver table but why would they update it so much? Personal information rarely changes and live information about the driver (trip status, position, online/offline) should be stored separate from that? And you wouldn't need transactions around those updates?

Did they ever clarify what data actually caused the issues?