Building Evolutionary Architectures

Chapter 5. Evolutionary Data

with contributions from Pramod Sadalage

Relational and other types of data stores are ubiquitous in modern software projects, a form of coupling that is often more problematic than architectural coupling. Data is an important dimension to consider when creating an evolvable architecture. It is beyond the scope of this book to cover all the aspects of evolutionary database design. Fortunately, our colleague Pramod Sadalage, along with Scott Ambler, wrote Refactoring Databases, subtitled Evolutionary Database Design. We cover only the parts of database design that impact evolutionary architecture and encourage readers to read this book.

When we refer to the DBA, we mean anyone who designs the data structures, writes code to access the data and use the data in an application, writes code that executes in the database, maintains and performance tunes the databases, and ensures proper backup and recovery procedures in the event of disaster. DBAs and developers are often the core builders of applications, and should coordinate closely.

Evolutionary Database Design

Evolutionary design in databases occurs when developers can build and evolve the structure of the database as requirements change over time. Database schemas are abstractions, similar to class hierarchies. As the underlying real world changes, those changes must be reflected in the abstractions developers and DBAs build. Otherwise, the abstractions gradually fall out of synchronization with the ...