But as we’ll see later, scaling data stores means making certain trade-offs among data consistency, node availability, and partition tolerance. Cassandra is frequently called “eventually consistent,” which is a bit misleading. Out of the box, Cassandra trades some consistency in order to achieve total availability. But Cassandra is more accurately termed “tuneably consistent,” which means it allows you to easily decide the

level of consistency you require, in balance with the level of availability.

Eventual consistency is one of several consistency models available to architects. Let’s take a look at these models so we can understand the trade-offs: