> It's entirely possible (no, extremely likely) that your EU node would have access to a different US node
CAP theorem beaten by declaring P to be unlikely.
CAP theorem beaten by declaring P to be unlikely.
https://medium.com/p/5e397cb12e63#7df1
Considering that this is maybe the 12th time I'm linking the explanation, I now think you're not looking for a discussion, you're here for a fight. Please let me know if you find any problems with the article in its reasoning. It was vetted by a lot of people before, so I really need to notify them too if you do.
Redundancy doesn't fix any problems, it just makes them less likely to occur. Again this not only does nothing to address the CAP theorem but is done for a wide array of problems already, there is nothing new here.
https://medium.com/p/5e397cb12e63#373c
There are three separate mitigation-solutions that go into how total-order strong consistency can keep marching on even if a specific child-group is intermittently isolated.
The first one is redundancy by deterministic replication, so there will always be many replicas which aren't just shards, but full copies of the _consistency ledger_. It's not a database, not a cache, just the thing that establishes the consistency between nodes. These instances all "race each other" to provide the first value of the outputs to other nodes.
The second one is the latency-mitigation we talked about earlier, I don't think we need to waste more breath on that.
The third one is that since the consistency-mechanism requires an explicit association-instruction to interleave the children's versions into its parent's (so that these versions can be exposed to nodes observing it from afar). If the child goes AWOL, it won't be able to associate its versions to its parent, so it won't keep up everyone else either. In this case the total-order won't be affected by the child-group's local-order, which is still allowed to make progress, as long as it's not trying to update any record that is distant to it.
2. Redundancy in network connection. Yes this can help. Again, it doesn't resolve anything CAP related, it just reduces the likelihood of a certain class of distributed systems fails. Note, there are LOTS of ways to have unbounded latency that this does not resolve. Anything from misconfigured routers to disk drives dying. Again, not resolving anything CAP states, just attempting to reduce the some probabilities.
3. If I understand this correctly, you are saying some data is "homed" in certain regions, and if that region becomes partitioned from the rest of the world, they can still modify the "homed" data there. They own it. This doesn't address anything CAP related.
Assuming I understand the architecture correctly, then yes, some architecture's will benefit from this. Some might not. But all of these decisions align with existing understanding and decisions architects make in the face of CAP.
It feels to me that you have believe CAP defines a very particular database architecture (something like a PostgreSQL) database, and your architecture addresses limitations in that, and thus your architecture solves limitations of CAP. But that's just not true. Take Riak, Cassandra, BigTable, Spanner, CockroachDB, all of these represent architectures defined in the face of CAP and they all have different trade-offs. They don't look a lot like PostgreSQL. But they cannot get around the simple laws of physics for how information is communicated.
But this is about the solution, not the science. The science is basically unlimited, its only real restriction is around our budget.
If you want to understand how the client-centric consistency mechanism takes care of these things, I write about it on medium and Twitter all the time.
But again, I don't feel like you owe me your time or attention
To summarise: we have a consistent system that works via one-way streaming, via redundant channels. Best possible cache-invalidation. Reads are both consistent and locally available. Upper-bound time of writes is predictable and doesn't suffer from blocking. I'm not sure what other improvements anyone could want from such a system, this is the best such systems can ever be. These improvements go well beyond the limits CAP sets out and it basically makes the whole argument moot.