A different, unified look at the data model of the key-value stores, document databases, and column-family stores from Martin Fowler:
there’s a big similarity between the first three - all have a fundamental unit of storage which is a rich structure of closely related data: for key-value stores it’s the value, for document stores it’s the document, and for column-family stores it’s the column family. In DDD terms, this group of data is an aggregate.
The aggregate approach was present in the relational databases world for quite a while. It came in two flavors: views and denormalization. The first one worked well for non-distributed deployments, while the second is used everywhere the speed or the usage of joins was not an option.
Original title and link: Key-Value Stores, Document Databases, and Column Stores as Aggregate Oriented Databases ( ©myNoSQL)