[转]Cassandra的 Consistency Level设置

最新推荐文章于 2025-04-26 18:42:57 发布

原创最新推荐文章于 2025-04-26 18:42:57 发布 · 2.9k 阅读

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本文详细介绍了在分布式系统中，写操作和读操作的一致性级别设置。对于写操作，包括ASYNC、ONE、QUORUM及ALL等不同级别的含义及其影响；对于读操作，则解释了ZERO、ANY、ONE、QUORUM及ALL等一致性级别的具体行为。

转自： http://blog.youkuaiyun.com/lzz313/article/details/5457313
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写操作

级别	内容
ZERO	Ensure nothing. A write happens asynchronously in background
ANY	(Requires 0.6) Ensure that the write has been written to at least 1 node, including hinted recipients.
ONE	Ensure that the write has been written to at least 1 node's commit log and memory table before responding to the client.
QUORUM	Ensure that the write has been written to <Replication> / 2 + 1 nodes before responding to the client.
ALL	Ensure that the write is written to all <Replication> nodes before responding to the client. Any unresponsive nodes will fail the operation.

读操作

级别	内容
ZERO	Not supported, because it doesn't make sense.
ANY	Not supported. You probably want ONE instead.
ONE	Will return the record returned by the first node to respond. A consistency check is always done in a background thread to fix any consistency issues when ConsistencyLevel.ONE is used. This means subsequent calls will have correct data even if the initial read gets an older value. (This is called read repair .)
QUORUM	Will query all nodes and return the record with the most recent timestamp once it has at least a majority of replicas reported. Again, the remaining replicas will be checked in the background.
ALL	Will query all nodes and return the record with the most recent timestamp once all nodes have replied. Any unresponsive nodes will fail the operation.