Attribute

ReadConsistency (RC)

Purpose

Specifies how many replicas must respond to a read request before returning data to the client application.

Valid Values

1 | 2 | 3 | 4 | 5 | 6 | 8 | 9 | 10

Behavior

If set to 1 (one), data is returned from the closest replica. This setting provides the highest availability, but increases the likelihood of stale data being read.

If set to 2 (two), data is returned from two of the closest replicas.

If set to 3 (three), data is returned from three of the closest replicas.

If set to 4 (quorum), data is returned after a quorum of replicas has responded from any data center.

If set to 5 (all), data is returned to the application after all replicas have responded. This setting provides the highest consistency and lowest availability.

If set to 6 (local_quorum), data is returned after a quorum of replicas in the same data center as the coordinator node has responded. This setting avoids latency of inter-data center communication.

If set to 8 (serial), the data is read without proposing a new addition or update. Uncommitted transactions are committed as part of the read.

If set to 9 (local_serial), the data within a data center is read without proposing a new addition or update. Uncommitted transactions within the data center are committed as part of the read.

If set to 10 (local_one), data is returned from the closest replica in the local data center.

Notes

  • If the server does not support the Read Consistency value specified, the connection attempt fails and the driver returns a consistency level error.
  • Refer to Apache Cassandra documentation for more information about configuring consistency levels, including usage scenarios.

Default

4 (quorum)

GUI Tab

Advanced tab