Distributed system - BASE

最新推荐文章于 2024-11-21 16:24:40 发布

转载最新推荐文章于 2024-11-21 16:24:40 发布 · 658 阅读

本文深入探讨了BASE（Basically Available, Soft State, Eventual Consistency）概念，这是一种在面对大规模系统中不可预知的故障时采取的权衡策略。它强调即使在短暂的时间内出现不一致的状态，系统最终仍能恢复正常运行并达到一致性的目标。通过对比传统的ACID（原子性、一致性、隔离性、持久性）原则，文章阐述了在某些场景下，选择BASE原则可以带来更高的可用性和效率。

BASE (Like the Opposite of ACID, Get It?)

You'll occasionally hear or read of the acronym BASE. This acronym captures one way of thinking about "good enough":

Basically available means that small failures don't generate large disabilities. It is the same idea as what we call "soft failure" vs "hard failure", but with the added emphasis that a few failures in a large scale system shouldn't really be noticable.

Soft state is usually intended to convey state that can be generated or refreshed upon demand, rather than necessarily being stored as "hard state". But, in this case, it is being used to convey that values, even after written, will continue to change without any explicit user request. Specifically, they'll propagate out slowly.

Eventual consistency conveys the idea that, although the system might be inconsistent for some time after an update, it will eventually converge to consistency. Without this property, or an approximation thereof, what good would the system be?

BASE is often contrasted with ACID. The idea being that traditional ACID semantics are very pessimistic and do a lot of work, assuming that any inconsistency would be noticed and result in disaster. BASE, by contrast, is vry optimistic and assumes that the inconsistencies are unlikely to result in disaster before they are eventually fixed.

The idea that we can trade off correctness for time, effort, and availability is a good one, as is the observation that favoring complete correctness and consistency at any cost, may be an unnecssary extreme -- depending upon the application....even if the acronym is, well, a little bit of a stretch.