Reminder that AWS Aurora claims to have broken the CAP theorem. The literature doesn’t clarify whether they are consistent or available, and when you ask AWS directly, they tell you the CAP theorem isn’t relevant due to the way Aurora is built.
They claim 99.99% availability or whatever the figure is, that it’s self healing, allows up to 2 replicas to be down for write availability and 3 replicas to be down for read availability. They promise “millisecond consistency”, whatever that even means.
Some of the blogs mention that they use distributed state to extract slivers of consistency across the nodes, which is just scary stuff to hear.
I’m seeing more and more usage of Aurora due to the magical component it offers, but I can’t wrap my head around what it’s actually supposed to be, and what the failure model is, like I can with RDS PG and MySQL.