Cassandra Consistency Level，

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.

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.