
297An Overview of the NoSQL World
They can be seen as a namespace for ColumnFamilies and is typically allocated
as one per application. SuperColumns represent columns that themselves have
subcolumns (e.g., Maps). Like Dynamo, Cassandra provides a tunable consistency
model that allows the ability to choose the consistency level that is suitable for a
specic application. For example, it allows to choose how many acknowledgments
are required to be received from different replicas before considering a WRITE
operation to be successful. Similarly, the application can choose how many suc-
cessful responses need to be received in the case of READ before ...