Comment by mjb

Practically, the difference in availability for typical internet connected application is very small. Partitions do happen, but in most cases its possible to route user traffic around them, given the paths that traffic tends to take into large-scale data center clusters (redundant, typically not the same paths as the cross-DC traffic). The remaining cases do exist, but are exceedingly rare in practice.

Note that I’m not saying that partitions don’t happen. They do! But in typical internet connected applications the cases where a significant proportion of clients is partitioned into the same partition as a minority of the database (i.e. the cases where AP actually improves availability) are very rare in practice.

For client devices and IoT, partitions off from the main internet are rare, and there local copies of data are a necessity.