> Not sure what you're getting at when you say ACID transactions don't work in a multi-DC context. I expect they are talking about DC as _regions_, not DC as _

> Not sure what you're getting at when you say ACID transactions don't work in a multi-DC context. I expect they are talking about DC as _regions_, not DC as _availability zones_ (in the AWS parlance). Planetary databases hit latency issues on cross-region ACID transactions. Whatever the sharding, a transaction modifying one piece whose leader is in Paris and another in Beijing will have at least the round-trip time between the two. It is already unforgiving at that scale, and will become inadmissible at interplanetary scale, requiring some form of eventual consistency. However, I still expect that we will retain ACID operations for local changes. Humans tolerate latencies that are necessary for planetary ACID transactions. The combination of the size of the Earth and the speed of light is a lucky draw.