Domain data often answers the question "what", e.g.

• What products are in inventory?
• What users have accounts on the system?
• What tests have been run?

Datomic's clean separation of reads and writes has inspired many comparisons with the CQRS (Command and Query Responsibility Segregation) architectural pattern.

One person who has traveled far down this road is Bobby Calderwood, a member of the Technology Fellows team at Capital One. Check out his recent Clojure/conj talk, where he demonstrates a complete CQRS implementation using Clojure microservices, Kafka, and Datomic. ..

Yeller is an exception tracking service whose goal is to provide clear, actionable information to developers to take the pain out of examining application errors. They chose Clojure and Datomic as the platform for Yeller in order to make the development process more effective and more efficient.

You can read all about their reasons for choosing Clojure and Datomic on their blog. You can also watch Tom explain it all at EuroClojure 2015. ..

Brazil is the world's 5th largest country in both area and population, has the 2nd most airports (behind the United States), and one of the highest credit card interest rates in the world. The Brazilian banking industry is both heavily regulated and extremely concentrated. Enter Nubank, whose founders have created a banking alternative in one of the world’s fastest growing mobile markets.

Traditional software wasn’t going to get the job done for Nubank. From the very beginning, the goal was “differentiation through technology.” They needed to plan for growth, both in size and complexity, to meet constantly changing regulatory and business rules.

Nubank turned to Datomic to access multiple data stores simultaneously, process transactions, and easily query historical data. Engineers can perform complex analyses on real-time data while the performance of the production environment is preserved. Along the way, the Cognitect team helped steer Nubank’s engineers on the right path as they built Datomic into their business.

Read the full case study to see how Datomic and Clojure are helping Nubank change the banking industry. ..

My colleague Carin Meier has been writing up her conversations with Datomic, introducing the database via an imagined dialog between a new user and the database.  In a very short space she introduces

• rapid development against a memory database
• schema definition
• hierarchical selection with pull
• Datalog query
• strong consistency
• retractions and history