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Comment by rdtsc | Hacker News Reader

> If you believe that partitions are inevitable, any distributed system

How does that answer it? Are they implying that partitions will not happen if you don't believe in them?

A CA system is not a system that doesn't have partitions, it's a system that works under the condition that there are no partitions (ie. it is a non-partition-resistant system).

A memcache cluster might qualify. If there's a partition, just forget about the missing nodes. It's just a cache anyway.

The system you describe would typically be referred to as AP, because it maintains availability in the presence of partitions.

> , it's a system that works under the condition that there are no partitions

But that is not a choice with distributed systems, unless as soon as a partition happens the system shuts down immediately. That is it effectively disappears and never re-appears again. But that's not a CA system then?

Or saying that it is not partition resistant is also difficult because the system in case of a partition will do _something_. The typical choices is that it either responds to clients (trying to be AP) or it doesn't (trying to be CP).

That is why I understand CA systems as equivalent to the belief that "partitions can't happen". Which I think is unrealistic.

This is a system which is guaranteed to be consistent and available as long as there are no partitions. If there are partitions, the system isn't guaranteed to be either.

Yes, it's a pretty much useless system.

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