Setting consistency levels
Set the consistency level to control the accuracy of the data returned by read request.
In a distributed system such as DataStax Distribution of Apache Cassandra™, the most
recent value of data is not necessarily on every node all the time. The client application
configures the consistency level per request to manage response time versus data accuracy. By
tracing activity on a five-node cluster, this tutorial shows the difference between these
consistency levels and the number of replicas that participate to satisfy a request:
- ONE
Returns data from the nearest replica.
- QUORUM
Returns the most recent data from the majority of replicas.
- ALL
Returns the most recent data from all replicas.
Follow instructions to setup five nodes on your local computer, trace reads at different consistency levels, and then compare the results.