At this point, most users should be aware that CQL has replaced Thrift as the standard (and therefore recommended) interface to work with Cassandra. However, it remains largely misunderstood, as its resemblance to common SQL has left both Thrift veterans and Cassandra newcomers confused about how it translates to the underlying storage layer. This fog must be lifted if you hope to create data models that scale, perform, and ensure availability.

As we begin this section, it is important to understand that the CQL data representation does not always match the underlying storage structure. This can be challenging for those accustomed to Thrift-based operations, as those were performed directly against the storage layer. However, CQL introduces an abstraction on top of the storage rows and only maps directly in the simplest of schemas.